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Table of Contents
REVIEW ARTICLE
Year : 2014  |  Volume : 18  |  Issue : 1  |  Page : 23-31

Thyroid and male reproduction


1 Department of Reproductive Biology, All India Institute of Medical Sciences, New Delhi, Intern, India
2 University College of Medical Sciences, Delhi, India

Date of Web Publication6-Feb-2014

Correspondence Address:
Anand Kumar
Department of Reproductive Biology, All India Institute of Medical Sciences, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2230-8210.126523

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   Abstract 

Male reproduction is governed by the classical hypothalamo-hypophyseal testicular axis: Hypothalamic gonadotropin releasing hormone (GnRH), pituitary luteinizing hormone (LH) and follicle stimulating hormone (FSH) and the gonadal steroid, principally, testosterone. Thyroid hormones have been shown to exert a modulatory influence on this axis and consequently the sexual and spermatogenic function of man. This review will examine the modulatory influence of thyroid hormones on male reproduction.

Keywords: Hyperthyroidism, hypothyroidism, Leydig cells, Sertoli cells, sperm function, Tri-iodothyronine


How to cite this article:
Kumar A, Shekhar S, Dhole B. Thyroid and male reproduction. Indian J Endocr Metab 2014;18:23-31

How to cite this URL:
Kumar A, Shekhar S, Dhole B. Thyroid and male reproduction. Indian J Endocr Metab [serial online] 2014 [cited 2018 Jun 23];18:23-31. Available from: http://www.ijem.in/text.asp?2014/18/1/23/126523


   Expression of Thyroid Hormone Receptors on Testis, Reproductive Tract and Accessory Sex Glands Top


Thyroid hormones exert their biological effects by binding to a specific nuclear thyroid hormone receptor (TR) which belongs to a family of ligand-dependent transcription factors. The receptor is encoded by two genes, c-erb Aα and c-erb Aβ. Alternative splicing of the c-erb Aα gene encodes three separate protein receptors α1, α2 and α3 whereas; the c-erbAβ gene encodes β1 and β2 receptors. [3]

Thyroid hormone receptors are widely distributed in the different compartments of the testis. In human fetal and adult Sertoli cells only the TRα1 and TRα2 isoforms are expressed; TRα2 expression being higher at all stages and the TRα2 /TRα1 ratio increases progressively from fetal to adult life. The TRβ isoform is absent in human Sertoli cells both in the fetal and adult stage. [4] In rats, the TRα1 is the predominant isoform expressed both in immature proliferating Sertoli cells and mature adult Sertoli cells. mRNAs of TRα2, TRα3 and TRβ1 are detected in Sertoli cells during development, but, their corresponding proteins are absent. [5]

Rat mesenchymal stem cells, immature and adult Leydig cells express the TRα isoform, their expression being maximal in the postnatal age and decreases to almost negligible levels in adulthood. T 3 binds specifically to nuclei of goat Leydig cells and consequently stimulates androgen production from these cells. [6],[7]

The presence of thyroid hormone receptors on germ cells suggests a probable role of thyroid hormones in sustaining different population of germ cells. Thryoid hormone receptors are identified on different stages of developing rat germ cells such as gonocyte, spermatogonia, preleptotene, leptotene, pachytene, zygotene, round and elongating spermatids. Both TRα and TRβ1 are expressed during different stages of germ cell development. TRβ1 first appears in intermediate type spermatogonia while TRα first appear in type B spermatogonia. [5]

The epithelial cells from the different segments of rat epididymis, caput, corpus and cauda, express thyroid hormone receptors. However, unlike classical TRs, the TRs in the epithelial cells of the epididymis are predominantly located in the cytoplasm. Both the TRα1 and TRβ1 isoforms are expressed in all three segments of the epididymis. Both the protein as well as mRNA levels of TR isoforms increase significantly in hypothyroid rats. [8] TRβ1 are also identified on the nuclear membrane of PZ HPV-10 cell line derived from prostatic tissue. [9]


   Testicular Actions of Thyroid Hormones Top


Sertoli cells

Sertoli cells provide support and sustain the developing germ cells. Each Sertoli cell supports a limited number of developing germ cells; the ratio of Sertoli cells to germ cells are 1: 11 in humans and 1:50 in adult rat testis respectively. [10],[11] Therefore, the number of Sertoli cells is one of the indicator of daily sperm production (DSP) of the testis. The development and maturation of Sertoli cells has two different stages; the proliferative stage and the terminally differentiated mature stage. In primates including human, Sertoli cell proliferation occurs over two distinct periods. The first expansion phase is similar to that in rodents. Additionally, there is a second proliferative stage in the peripubertal life before proliferation finally stops. The maturation of immature Sertoli cells to the mature stage is characterized by certain morphological changes which include the nucleus enlarging and becoming tripartite and the nucleolus becoming more prominent, loss of proliferative ability and formation of inter-Sertoli cell junctions. [12],[13]

In Sertoli cells, expression of certain genes and proteins are associated with its maturational status. Anti-Mullerian hormones (AMH), aromatase, neural cell adhesion molecule (NCAM) are expressed exclusively by immature Sertoli cells whereas; p27 Kip1 , p21 Cip1 , androgen receptor (AR) are characteristic markers of mature Sertoli cells. [12]

T 3 suppresses the expression of immature Sertoli cells markers, including AMH, aromatase and NCAM. Hypothyroidism induced in neonatal rats, delayed the fall in AMH mRNA levels and T 3 treatment decreased AMH mRNA in Sertoli cells. [14] In mouse Sertoli cell line, TM4, T 3 decreased transcription of aromatase gene. [15] T 3 down-regulates NCAM production in Sertoli cell-germ cell co-cultures. [16]

T 3 increases the levels of cell cycle inhibitory proteins p27 Kip1 and p21 Cip1 in Sprague-Dawley rats. These inhibitory proteins are negative regulators of cyclin-dependent kinases Cdk2 and Cdk4 required for G1 to S transition in the cell cycle. [17] Additionally, AR mRNA levels in 5- and 20-day-old cultured Sertoli cells were significantly increased by T 3 . [18]

In contrast, T 3 maintains inter-Sertoli cell junctions by regulating the levels of gap junction protein, Connexin. T 3 increased the levels of Connexin 43 (Cx43; the most abundant gap junction protein) in Sertoli cell cultures. [19] Two specific inhibitors of Cx43, AGA and oleamide, significantly lowered the T 3 induced Cx43 levels in cultured Sertoli cells. [19]

Leydig cells

The stem cells for both fetal and adult Leydig cells populations are the mesenchymal cells in the testis intersitium, which are spindle-shaped and non-steroidogenic. While some of the mesenchymal cells differentiate into fetal Leydig cells others retain their undifferentiated characteristics and serve as precursor cells for the adult Leydig cells in the postnatal testis. [20]

Thyroid hormones regulate Leydig cell development and steroidogenesis. Hardy et al., (1993) [21] have shown that propylthiouracil (PTU) treated hypothyroid rats showed a significant increase in Leydig cell number when compared to euthyroid controls. However the isolated Leydig cells from these hypothyroid rats had a 50% lower hCG binding sites and exhibited lower steroid producing potential. [21] They later showed that the increase in adult Leydig cell population was mainly due to proliferation of immature Leydig cells. [7] In their elegant studies, Ariyaratne et al., (2000) [22] have shown that thyroid hormone is essential for differentiation of mesenchymal stem cells into Leydig cells in adult rats. Ethane dimethanesulfonate (EDS), a specific destroyer of Leydig cells, completely eliminated Leydig cell population in adult Sprague- Dawley rats by 2 days of treatment. The Leydig cells reappeared by 14 and 21 days in euthyroid and T 3 treated rats respectively. The number of new Leydig cells was double in the T 3 treated rats in comparison to euthyroid controls. In PTU treated hypothyroid rats, Leydig cells did not appear at all. In the rats made hypothyroid by propyl thiouracil (PTU) treatment or thyroidectomy, Leydig cells did not appear at all. Thus, they have concluded that T 3 facilitates the differentiation of mesenchymal stem cells into Leydig cells. [22]

Thyroid hormones also influence Leydig cell steroidogenesis. Leydig cells synthesize steroid hormones from cholesterol. Leydig cells take up lipoprotein-cholesterol ester from the circulation via specific lipoprotein receptors. A small fraction of cholesterol is also de-novo synthesized from acetyl CoA in the Leydig cells. Cholesterol derived from either source is esterified by cholesterol acyl transferase and stored in Leydig cells cytoplasmic lipid droplets. Upon LH stimulation, cholesteryl ester is hydrolysed and is released from the lipid droplets. Steroidogenic acute regulatory protein (StAR), a de novo synthesized labile protein, catalyzes the translocation of cholesterol from outer to the inner mitochondrial membrane. Steroidogenic factor 1 (SF-1), a 52 KDa orphan nuclear receptor transcription factor, regulates the transcription of StAR gene. The StAR gene promoter has two conserved regions that govern basal and cAMP-regulated gene expression. SF-1 bind to the distal site on StAR promoter region with high affinity whereas; binding affinity between the proximal site and SF-1 is only moderate. Binding of SF-1 to either of the binding sites enhances basal and cAMP stimulated StAR gene transcription. [23],[24]

In the inner mitochondrial membrane, cholesterol is converted to pregnenolone catalyzed by cytochrome P450 side-chain cleavage enzyme (cyt P450 scc enzyme) using nicotinamide adenine dinucleotide phosphate-oxidase NADPH as a cofactor. Pregnenolone then diffuses out to cytoplasmic endoplasmic reticulum where remaining steps of testosterone biosynthesis are carried out. The conversion of pregnenolone to testosterone occurs via two distinct pathways, Δ4 and Δ5 pathway as shown in [Figure 1].
Figure 1: Schematic representation of Leydig cell steroidogenesis

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Jana and Bhattacharya (1994) [7] have shown that T 3 stimulates testosterone production by goat Leydig cells in a dose dependent manner. They have later shown that T 3 induces de novo synthesis of a 52 KDa soluble protein, which augments the androgen production in the Leydig cells. [25] Similarly, T 3 increased testosterone production by the rat and mouse Leydig cells in vitro, [26],[27] and its precursor, progesterone, by a Leydig tumor cell derived line, MLTC-1 by about 300%. [27] T 3 treatment for 8h increased StAR mRNA in MLTC-1 and mouse Leydig cells. [27] However, chronic stimulation of MLTC-1 cells with T 3 beyond 8h and uptill 30h decreased StAR mRNA and protein levels and also the steroid production. T 3 does not alter StAR mRNA stability but decreases its transcription. The reduction in progesterone production upon T 3 exposure (30h) was partially restored by 22R hydroxycholesterol (lipid soluble side-chain oxygenated sterol which can directly diffuse from the outer mitochondrial to the inner mitochondrial membrane without the need for StAR) or pregnenolone. These results confirm that the site of steroidogenic inhibition by T 3 is the StAR protein. T 3 treatment for 30h shows a significant increase in P450 scc enzyme responsible for catalyzing the conversion of cholesterol to pregnenolone, but also a decrease in pregnenolone metabolizing enzyme 3β-HSD mRNA. Thus, a chronic exposure of the cells to T 3 inhibits StAR mRNA, StAR protein and pregnenolone to progesterone converting enzyme 3β-HSD. [28]

T 3 also increases hCG binding to the MLTC-1 cells; the binding peaks at 16h and thereafter the binding decreases in a time dependent manner. In hypothyroid mice, there was a significant increase in LHR-mRNA and hCG binding in the Leydig cells. In contrast, in hyperthyroid mice, LHR-mRNA and hCG binding decreases. Manna et al., (2001) [28] showed that action of T 3 is mediated via a 173-bp fragment on the Luteinizing hormone receptor LHRgene promoter region. Mutation studies showed that the SF-1 binding region on the mouse StAR promoter region is involved in T 3 response. [28]


   Sperms and Fertility Top


Sperm count

Hypothyroidism induced in rats by PTU treatment during the critical period of the first postnatal week resulted in a significant increase in testis weight, DSP and efficiency of sperm production. [29] The rise in sperm production could be attributed to different causes such as (1) a rise in gonadotropins, LH and FSH, which are important for spermatogenesis and germ cell survival (2) increase in Sertoli cell number and (3) decrease in germ cell apoptosis. Serum gonadotropins are reduced in PTU treated hypothyroid rats eliminating the fact that the rise in sperm production was due to increase in LH and FSH levels. [30] The hypothyroid rats have significantly higher number of Sertoli cells which in turn supports the recruitment and survival of greater number of germ cells. [31] In rats large number of germ cells undergoes apoptosis during the third postnatal week; this period is characterized by a significant rise in pro-apoptopic proteins of both the intrinsic and extrinsic apoptopic pathways. Silva et al., (2011) [32] studied whether the apoptosis of germ cells is due to an intrinsic property of germ cell or whether it is dependent on Sertoli cell. In rats made hypothyroid by PTU treatment there was a delay in differentiation of immature Sertoli cells to the mature state as was evident by delayed expression of clusterin, a marker of differentiated Sertoli cell. In these hypothyroid rats the delay in Sertoli cell differentiation resulted in (1) delay in differentiation of spermatocyte to the more matured germ cell stage and (2) delay in germ cell apoptosis; maximum apoptosis seen on day 45 as compared to day 25. Thus, even though thyroid hormones does not act directly on germ cell apoptosis but it delays Sertoli cell maturation which results in delayed germ cell apoptosis. [32]

Sperm morphology

Morphological abnormalities in the development or proper shaping of sperm head may result in deformed heads and greatly reduces its potential to fertilize a mature oocyte. Morphological deformities in the tail region result due to defects in different parts of the tail. Both hyperthyroid and hypothyroid men had lower proportion of morphologically normal sperm. [33],[34] Thyroid hormones exert their effect on cell cytoskeleton. Zamoner et al., (2008) [35] reported that in Sertoli cells of hypothyroid rats, the phosphorylation and the immunoreactivity of cytoskeleton-associated vimentin protein was increased without any change in its expression. This results in loss of Sertoli cell cytoskeleton integrity. The high proportion of morphologically abnormal sperm observed in altered thyroid state could be due to effect of thyroid hormones on sperm cytoskeleton.

Motility

Hypothyroid and hyperthyroid patients showed a decrease in progressive forward motility of the sperm. [36],[37],[38] Thyroid hormones increases basal metabolic rate and stimulate oxygen consumption in metabolically active cells. Thyroid hormones stimulate cellular oxygen consumption by promoting the action of Na + /K + ATPases, [39] increasing mitochondrial number and mitochondrial gene expression. [3] The role of T 3 on ATP generation in males is speculated. However, specific studies on the modulatory effect of T 3 on sperm ATPases and energy production needs to be studied.

Fertility

Gestational exposure of rats to methimazole (MMI) resulted in a reduction in testicular interstitial fluid (TFI) levels of testosterone and estradiol. The hypothyroid rats showed reduced pregnancy induction capacity when mated with normal females and the litter size was also substantially reduced. Additionally, the ratio of male to female pups was also reduced significantly. [40]


   Thyroid Hormones and Reproductive Tract and Sex-Accessory Glands Top


Thyroid hormones influence both epididymal structure and its secretary activity. Gestational exposure of rats to MMI resulted in reduced epididymal weight but sperm content in cauda and corpus epididymis remained unchanged. The caudal sperm forward motility decreased significantly. The epididymal secretions such as sialic acid, glycerophosphotylcholine and carinitine were also reduced in these hypothyroid rats. Gestational MMI exposure also decreased 5α-reductase and AR levels. [40]

Thyroid hormones regulate the contractile activity of vas deferens in response to prostaglandin E 2 (PGE 2 ). Removal of thyroid glands in albino rats completely inhibited the contractile activity of vas deferens in response to PGE 2 . But treatment of T 4 further increased the contractibility of vas deferens in response to PGE 2 . [41]

In PTU induced hypothyroid rats there was a significant fall in their seminal vesicle and prostate gland weight. [42] Geatational MMI exposure to rats decreased AR mRNA levels in dorsolateral prostate lobe but surprisingly increased AR mRNA levels in ventral lobe in pups. [43] Maran et al. (1998) [44] reported a stimulatory effect of thyroid hormones on rat prostatic glycosidase activities such as β-glucosidase, β-galactosidase, β-N-acetylglucosaminidase and β-N-acetylgalactosaminidase while opposite effects were reported in thyroidectomized rats. [44] Thyroid hormones regulate glycoprotein metabolism differently in the different prostatic lobes. T 3 decreased hexosamines and sialic acid concentrations in ventral prostatic tissues of 30 and 60 day old thyroidectomized rats. Fucose concentrations in the ventral prostatic tissues increased at 30 days but decreased at 60 days in these hypothyroid rats. [44] In the dorsolateral prostatic lobe, hypothyroidism enhanced the concentration of hexosamines but resulted in a decrease in fucose, sialic acid and fructose levels irrespective of the duration of hypothyroidism. In the anterior prostate, hypothyroidism decreased fucose, fructose and hexosamines levels and increased sialic acid concentration in 60-day old rats. [44] Thyroid hormones influence the risk of prostate cancer through their function in cell differentiation, growth and metabolism. Hypothyroid men showed a decreased risk of prostate cancer when compared to euthyroid men, although no associations between hyperthyroidism and risk of prostate cancer could be established. [45]


   Thyroid Hormones and Oxidative Stress Top


Reactive oxygen species (ROS) are highly chemically reactive reduced forms of oxygen and their products with other molecules. All ROS including superoxide radical, hydroxyl radical, hydrogen peroxide contain one or more unpaired electrons. Mitochondria are the primary biological source of ROS. Under physiological conditions ROS can oxidize a number of biological molecules such as unsaturated fatty acids, sulphydryl proteins and nucleic acids. [46] To counteract the effects of ROS, cells produce many anti-oxidant molecules such as superoxide dismutase (SOD), glutathione peroxidise (GSHPx), catalase (CAT), tocopherols, carotenoids. Oxidative stress results when ROS levels are much higher than anti-oxidant levels in the cells. [46]

In the semen, sperm and some leukocytes contaminating the seminal plasma are the principal source of ROS. The sperm plasma membrane has a high amount of polyunsaturated fatty acids such as docosahexaenoic acid, which are rapidly oxidized by ROS thereby decreasing the flexibility and motility of the sperm tail. [47] ROS also decreases ATP generated by sperm mitochondrial sheath which provides energy for sperm motility. [48] Teratozoospermic sperm in most cases retain excess residual body which is normally lost during sperm maturation. These residual bodies has large amount of glucose-6-phosphate dehydrogenase which generates NADPH. NADPH produces ROS catalyzed by the NADPH oxidase enzyme present in sperm plasma membrane. [49]

Thyroid hormones are important in maintaining the balance between ROS and anti-oxidant molecules in many tissues including testis. Zamoner et al., (2008) [35] showed that the oxygen consumption of testis in the new-born hypothyroid rats was significantly lower than the euthyroid controls but there was no difference in their lipid peroxide levels. The anti-oxidant SOD activity was significantly lowered in hypothyroid group in comparison to controls. These observations suggest that although ROS levels do not increase but reduced anti-oxidant activity could lead to oxidative stress in a hypothyroid state. [35] In PTU treated rats hydrogen peroxide and protein carbonyl content level in the crude homogenate of testis increased but the endogenous lipid peroxide levels remain unaltered. There was a fall in SOD and catalase activity in hypothyroid rats but on addition of T 3 , only the catalase activity was enhanced without any change in SOD activity. [42]


   Reproductive Dysfunctions in Thyroid Disorders Top


Thyroid disorders are mainly categorized into two groups; hypothyroidism and hyperthyroidism. As explained earlier thyroid hormones are important regulator of male reproductive function so any alterations in their serum levels have profound effects on male reproduction.


   Hypothyroidism Top


Reproductive endocrine profile

Several studies have shown a fall in circulating testosterone levels in hypothyroid patients [50],[51] whereas; Velazquez and Arata (1997) [52] found no change in free testosterone levels in hypothyroid men. Jaya Kumar (1990) [50] found a rise in serum LH and FSH levels, but Velazquez and Arata (1997) [52] found a rise in only FSH levels without any change in LH levels. Donnelly and White, (2000) [51] found no change in serum LH and FSH levels in hypothyroid men. Thyroid hormones also alter pituitary response to GnRH. Administration of GnRH to hypothyroid patients resulted in an attenuated LH response. [53]

In hypothyroid males we found a significant decrease in gonadal steroids - progesterone and total testosterone. Bioavailable testosterone (BioT) or physiologically available testosterone, calculated by Morris's formula, [54] was also reduced in hypothyroid men [Figure 2]. Morris et al., (2004) [54] measured serum total T and sex hormone binding globulin (SHBG) by ELISA, Bio T by Tremblay and Dube's method (1974), [55] calculated percent free T, and free T by Nanjee's formula (1985) [56] and Vermeulen's computer program (1999) [57] respectively. On the basis of above calculations, they developed and validated an equation for the calculation of Bio T. They concluded that total T is the best predictor of Bio T. The fall in testosterone levels could be due to 1) low cholesterol uptake by Leydig cells as evident from high serum cholesterol levels 2) lower conversation of progesterone to testosterone as suggested by low testosterone/progesterone ratio 3) higher conversion of estradiol to testosterone as suggested by high estradiol to testosterone ratio and 4) hyperprolactanemia. High prolactin suppresses 17α-hydroxylase enzyme in rat testicular cells which catalyzes the conversion of progesterone to 17α-hydroxy progesterone. [58] Though serum testosterone and BioT levels were low in hypothyroid men we reported a normal levels of gonadotropins. This raised a question about the role of testosterone on the feedback inhibition of pituitary gonadotropin release. In our studies serum levels of estradiol were not different between euthyroid and hypothyroid men, suggesting the primary role of estradiol in the feedback regulation of pituitary gonadotropin secretion. [59],[60] Our suggestions about estradiol being the prime regulator of negative feedback on pituitary levels of gonadotropins instead of testosterone are corroborated by the findings of Rochira et al., Their study showed that basal and GnRH stimulated LH and FSH secretion was higher than normal in aromatase-deficient men with normal testosterone levels. However, estrogen administration to these aromatase deficient men resulted in a decrease in pulse amplitude and frequency of LH and pulse amplitude of FSH establishing the role of estrogens on gonadotropin secretion in adult male with aromatase deficiency. [61],[62]
Figure 2: (a-c) Serum hormone levels in hypothyroid men. Bar I and II represent mean ± SEM of normal (n= 22) and hypothyroid patients (n= 12) (adapted from Kumar et al, 2007, Andrologia)

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Cretinism

A study on Chinese cretins revealed some interesting facts about their endocrine profile and sexual function. Clinically these patients showed symptoms of both myxoedematous and neurological cretinism. The majority of cretins (65%) had normal TSH levels; however, 35% was hypothyroid with very high TSH levels (mean value 180mIU/L). The hypothyroid cretins showed a significant rise in serum LH, FSH and prolactin levels. 13% of euthyroid cretins and 39% of hypothyroid cretins showed testicular volume lower than 10ml suggesting hypogonadism. [63]

Role of TSH vs thyroid hormones

Hypothyroid men had high TSH levels and low thyroid hormone levels confounding the exact mechanism of inhibition of testicular steroidogenesis - whether it is low levels of T 3 or raised TSH. To address this issue we studied subclinically hypothyroid men with TSH levels lower than 10mIU/L. These patients showed an endocrine profile similar to frankly hypothyroid males. They showed a significant fall in levels of serum testosterone and progesterone, rise in serum prolactin levels but no significant change in pituitary gonadotropin and estradiol levels. As only TSH is raised in subclinical hypothyroid patients without any change in thyroid hormones this could suggest a possible role of TSH in regulating gonadal steroidogenesis in males. However, till date there is no direct evidence suggesting that TSH regulates gonadal steroidogenesis in males. An earlier report had shown that TSH increased cAMP in human cryopreserved testicular slices. But the TSH doses used were very high (100-20,000 microIU/ml) and the preparation could have been contaminated by other pituitary hormones. [64]

To confirm the role of TSH further we recruited normal men with TSH values 1.75 ± 0.82μIU/ml and men with low TSH, mean values 0.13 ± 0.12μIU/ml (Reference range of TSH 0.35-4.94μIU/ml) and normal T 3 and T 4 . These patients did not show a change in serum LH, FSH, testosterone, BioT, progesterone, estradiol and SHBG levels. However, lack of effect of low TSH does not rule out the lack of action of raised levels of TSH on gonadal functions (unpublished data from our laboratory).

Sperm function and semen

In hypothyroidism, men with normal sperm morphology were significantly lower than controls. But on treatment with levothyroxine there was a significant improvement on morphology. Sperm motility was also reduced in hypothyroid men but the reduction was not significantly lower than controls. Subclinical hypothyroidism does not affect semen and sperm parameters in adult males. [65]

Sexual function

Hypothyroid males also show altered sexual behavior. In adult hypothyroid males impaired sexual behavior including hypoactive sexual desire (HSD), erectile dysfunction (ED) and ejaculatory disorders are prevalent. In these hypothyroid patients the sexual behavior improved with restoration of euthyroid status. [2] The exact cause of sexual dysfunction in hypothyroidism is not clear. It could be attributed to persistent mild hyperprolactinemia as reported in the hypothyroid patients or it could be due to a rise in estrogen to testosterone ratio as reported by us and other or due to a CNS effect.

Hyperthyroidism

In our studies we found serum levels of testosterone and estradiol were raised in hyperthyroid men but their progesterone levels were similar to euthyroid controls. [66] A similar rise in serum testosterone and estradiol levels was also reported by others. [37],[38]

Testosteone to progesterone ratio in the hyperthyroid group was significantly higher, suggesting a higher conversion rate of progesterone to testosterone. However, normal levels of progesterone in spite of increased conversion to testosterone imply an increased synthesis of progesterone. Fall in serum total cholesterol and LDL-C levels in hyperthyroid men suggest an increased utilization of serum cholesterol which may further be utilized for increased progesterone synthesis. [66]

The increase in serum estradiol levels indicates an increase in peripheral aromatization of testosterone to estradiol. Further, hyperthyroidism being a state of hyperdynamic circulation is expected to increase the tissue blood flow and thereby an increased availability of testosterone to the peripheral tissues for aromatization. [67]

Hudson and Edwards, (1992) [37] have reported an increase in dialyzable free estradiol and without any change in dialyzable free testosterone. They calculated a decrease in free testosterone to free estradiol ratio suggesting an increased aromatization of testosterone. However, we [66] reported an increase in calculated bioT and an unaltered total estradiol to testosterone ratio in hyperthyroid patients. The doubling of estradiol levels per se too suggested a rise in aromatization.

Kumar et al., (2012) [66] also reported an increase in serum SHBG in hyperthyroid men. SHBG decreases the metabolic clearance rate of testosterone which could partly attribute to increase in serum total testosterone levels observed in hyperthyroid men. Inspite of raised SHBG levels, there is sufficient amount of circulating unbound testosterone available as evident by a rise in calculated bioT.

During the pre-ovulatory stage, the positive feedback of estradiol is characterized by 3-12-fold rise in LH levels in cycling females. [59],[60] Barbarino et al., (1983) [68] demonstrated that maintenance of serum estradiol concentration similar to that present in women at mid-cycle, for a period of 96-122h, lead to a surge of LH in both intact and castrated men. However, the magnitude of LH surge was not as huge as found in females. In our studies, we too report a similar positive feedback effect of raised estradiol levels on LH secretion; suggesting a key role of estrogen in regulating serum gonadotropin levels. The rise in LH was not as high as seen in cycling females which could result due to high testosterone levels [Figure 3]. [66] Boucekkine and Semrouni (1990) [69] examined the effect of estradiol on basal and GnRH − stimulated gonadotropin secretion in patients with Klinefelter's syndrome. Injections of estradiol to these patients for five days, induced an initial decline in the serum revels of FSH and LH, followed by a 6.6-fold rise in estradiol levels on day three and 1.7- fold increase in LH levels on day four of the injection. However, FSH levels remained suppressed till day seven. Their results also demonstrated the establishment of a positive feedback of estradiol on LH secretion in patients with Klinefelter's syndrome.
Figure 3: Serum LH and estradiol levels in hyperthyroid (n=12) and euthyroid (n = 17) males (adapted from Kumar et al, 2011, Andrologia)

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   Sperm Function and Semen Top


In hyperthyroid men there was a significant decrease in semen volume, sperm count, sperm motility and number of morphologically normal sperm. [33],[34]


   Breasts Top


Hyperthyroidism is often associated with gynecomastia. [70] Karnath (2008) [70] suggested a rise in serum SHBG and a subsequent fall in unbound testosterone as a probable cause for development of gynecomastia in hyperthyroid men. As we had already mentioned Hudson and Edwards, (1992) [37] reported a fall in free testosterone to free estradiol ratio and suggested this hormonal imbalance could lead to gynecomastia. However, we [66] calculated a raised bioT levels without any change in estradiol to testosterone ratio in hyperthyroid patients. Therefore, the ratio of estradiol to testosterone might not be as important as the rise of estradiol and its action through its specific receptors in the development of gynecomastia.


   Sexual Functions Top


In hyperthyroid men also, as was in hypothyroid patient impairment in sexual behavior was reported. There is a higher prevalence of HSD, ED and ejaculatory disorders in them. A return to euthyroid state reversed the abnormality in sexual functions. [2]


   Conclusion Top


In conclusion, normal putative thyroid activity seems a requisite for male reproductive functions. Thyroid disorders distinctly affect the reproductive health of the male. However, the knowledge about the interaction between the two classical endocrine axes, hypothalamo-hypophyseal-testicular axis and hypothalamo-pituitary-thyroid axis, is still rudimentary and needs further investigation.

 
   References Top

1.Singh R, Marie GM, Lee W, Agarwal A. Thyroid, spermatogenesis and male infertility. Front Biosci 2011;E3:843-55.  Back to cited text no. 1
    
2.Krassas GE, Poppe K, Glinoer D. Thyroid function and human reproductive health. Endocr Rev 2010;31:702-55.  Back to cited text no. 2
    
3.Wrutniak-Cabello C, Casas F, Cabello G. Thyroid hormone action in mitochondria. J Mol Endocrinol 2001;26:67-77.  Back to cited text no. 3
    
4.Jannini EA, Crescenzi A, Rucci N, Screponi E, Carosa E, De Matteis A, et al. Ontogenetic pattern of thyroid hormone receptor expression in the human testis. J Clin Endocrinol Metab 2000;85:3453-7.  Back to cited text no. 4
    
5.Buzzard JJ, Morrison JR, O'Bryan MK, Song Q, Wreford NG. Developmental expression of thyroid hormone receptors in the rat testis. Biol Reprod 2000;62:664-9.  Back to cited text no. 5
    
6.Hardy MP, Sharma RS, Arambepola NK, Sottas CM, Russell LD, Bunick D, et al. Increased proliferation of Leydig cells induced by neonatal hypothyroidism in the rat. J Androl 1996;17:231-8.  Back to cited text no. 6
    
7.Jana NR, Bhattacharya S. Binding of thyroid hormone to goat testicular cell induces generation of a proteinaceous factor which stimulates androgen release. J Endocrinol 1994;143:549-56.  Back to cited text no. 7
    
8.De Paul AL, Mukdsi JH, Pellizas CG, Montesinos M, Gutierrez S, Susperreguy S, et al. Thyroid hormone receptor alpha 1-beta 1 expression in epididymal epithelium from euthyroid and hypothyroid rats. Histochem Cell Biol 2008;129:631-42.  Back to cited text no. 8
    
9.Hsieh ML, Juang HH. Cell growth effects of triiodothyronine and expression of thyroid hormone receptor in prostate carcinoma cells. J Androl 2005;26:422-8.  Back to cited text no. 9
    
10.Bendsen E, Byskov AG, Laursen SB, Larsen HE, Andersen CY, Westergaard LG. Number of germ cells and somatic cells in human fetal testes during the first weeks after sex differentiation. Hum Reprod 2003;18:13-8.  Back to cited text no. 10
    
11.Mruk DD, Cheng Y. Sertoli-Sertoli and Sertoli-Germ cell interactions and their significance in germ cell movement in the seminiferous epithelium during spermatogenesis. Endocr Rev 2004;25:747-806.  Back to cited text no. 11
    
12.Sharpe RM, McKinnell C, Kivlin C, Fisher JS. Proliferation and functional maturation of Sertoli cells, and their relevance to disorders of testis function in childhood. Reproduction 2003;125:769-84.  Back to cited text no. 12
    
13.Walker WH. Molecular mechanisms controlling Sertoli cell proliferation and differentiation. Endocrinology 2003;144:3719-21.  Back to cited text no. 13
    
14.Bunick D, Kirby J, Hess RA, Cooke PS. Developmental expression of testis messenger ribonucleic acids in the rat following propylthiouracil-induced neonatal hypothyroidism. Biol Reprod 1994;51:706-13.  Back to cited text no. 14
    
15.Catalano S, Pezzi V, Chimento A, Giordano C, Carpino A, Young M, et al. Triiodothyronine decreases the activity of the proximal promoter (PII) of the aromatase gene in the mouse Sertoli cell line, TM4. Mol Endocrinol 2003;17:923-34.  Back to cited text no. 15
    
16.Laslett AL, Li LH, Jester WF Jr, Orth JM. Thyroid hormone downregulates neural cell adhesion molecule expression and affects attachment of gonocytes in Sertoli cell-gonocyte cocultures Endocrinology 2000;141:1633-41.  Back to cited text no. 16
    
17.Buzzard JJ, Wreford NG, Morrison JR. Thyroid hormone, retinoic acid, and testosterone suppress proliferation and induce markers of differentiation in cultured rat Sertoli cells. Endocrinology 2003;144:3722-31.  Back to cited text no. 17
    
18.Arambepola NK, Bunick D, Cooke PS. Thyroid hormone and follicle-stimulating hormone regulate Mullerian-inhibiting substance messenger ribonucleic acid expression in cultured neonatal rat Sertoli cells. J Endocrinol 1998;139:4489-95.  Back to cited text no. 18
    
19.Gilleron J, Nebout M, Scarabelli L, Senegas-Balas F, Palmero S, Segretain D, et al. A potential novel mechanism involving connexion 43 gap junction for control of Sertoli cell proliferation by thyroid hormones. J Cell Physiol 2006;209:153-61.  Back to cited text no. 19
    
20.Mendis-Handagama SM, Ariyaratne HB. Differentiation of the Adult Leydig Cell Population in the Postnatal Testis. Biol Reprod 2001;65:660-71.  Back to cited text no. 20
    
21.Hardy MP, Kirby JD, Hess RA, Cooke PS. Leydig cell increase their numbers but decline in steroidogenic function in the adult after neonatal hypothyroidism. Endocrinology 1993;132:2417-20.  Back to cited text no. 21
    
22.Ariyaratne HB, Mills N, Mason IJ, Mendis-Handagama SM. Effects of thyroid hormone on Leydig cell regeneration in the adult rat following ethane dimethane sulphonate treatment. Biol Reprod 2000;63:1115-23.  Back to cited text no. 22
    
23.Sugawara T, Holt JA, Kiriakidou M, Strauss JF. Steroidogenic factor 1-dependent promoter activity of the human steroidogenic acute regulatory protein (StAR) gene. Biochemistry 1996;35:9052-9.  Back to cited text no. 23
    
24.Sugawara T, Kiriakidou M, McAllister JM, Kallen CB, Strauss JF. Multiple steroidogenic factor 1binidng elements in the human steroidogenic acute regulatory protein gene 5'-flanking region are required for maximal promoter activity and cyclic AMP responsiveness. Biochemistry 1997;36:7249-55.  Back to cited text no. 24
    
25.Jana NR, Halder S, Bhattacharya S. Thyroid hormone induces a 52 kDa soluble protein in goat testis Leydig cell which stimulates androgen release. Biochem Biophys Acta 1996;1292:209-14.  Back to cited text no. 25
    
26.Maran RR, Arunakaran J, Aruldhas MM. T 3 Directly stimulates basal and modulates LH induced testosterone and estradiol production by rat Leydig cells in vitro. Endocrine J 2000;47:417-28.  Back to cited text no. 26
    
27.Manna PR, Tena-Sempere M, Huhtaniemi IT. Molecular mechanisms of thyroid hormone-stimulated steroidogenesis in mouse leydig tumor cells. J Biol Chem 1999;274:5909-18.  Back to cited text no. 27
    
28.Manna PR, Kero J, Tena-Sempere M, Pakarinen P, Stocco DM, Huhtaniemi IT. Assessment of mechanisms of thyroid hormone action in mouse Leydig cells: Regulation of the Steroidogenic Acute Regulatory Protein, steroidogenesis and luteinizing hormone receptor function. Endocrinology 2001;142:319-31.  Back to cited text no. 28
    
29.Cooke PS, Hess RA, Porcelli J, Meisami E. Increased sperm production in adult rats after transient neonatal hypothyroidism. Endocrinology 1991;29:244-8.  Back to cited text no. 29
    
30.Kirby JD, Jetton AE, Cooke PS, Hess RA, Bunick D, Ackland JF, et al. Developmental hormonal profiles accompanying the neonatal hypothyroidism-induced increase in adult testicular size and sperm production in the rat. Endocrinology 1992;131:559-65.  Back to cited text no. 30
    
31.Hess RA, Cooke PS, Bunick D, Kirby JD. Adult testicular enlargement induced by neonatal hypothyroidism is accompanied by increased Sertoli and germ cell numbers. Endocrinology 1993;132:2607-13.  Back to cited text no. 31
    
32.Silva D, Lizama C, Tapia V, Moreno RD. Propylthiouracil-induced hypothyroidism delays apoptosis during the first wave of spermatogenesis. Biol Res 2011;44:181-8.  Back to cited text no. 32
    
33.Krassas GE, Pontikides N, Deligianni V, Miras K. A prospective controlled study of the impact of hyperthyroidism on reproductive function in males. J Endocrinol Metab 2002;87:3667-71.  Back to cited text no. 33
    
34.Krassas GE, Papadopoulou F, Tziomalos K, Zeginiadou T, Pontikides N. Hypothyroidism has an adverse effect on human spermatogenesis: A prospective, controlled study. Thyroid 2008;18:1255-9.  Back to cited text no. 34
    
35.Zamoner A, Barreto KP, Filho DW, Sell F, Woehl VM, Guma FC, et al. Propylthiouracil-induced congenital hypothyroidism upregulates vimentin phosphorylation and depletes antioxidant defences in immature rat testis. J Mol Endocrinol 2008;40:125-35.  Back to cited text no. 35
    
36.Corrales-Hernandez JJ, Miralles-Garcia JM, Garcia-Diez LC. Primary hypothyroidism and human spermatogenesis. Arch Androl 1990;25:21-7.  Back to cited text no. 36
    
37.Hudson R, Edwards A. Testicular function in hyperthyroidism. J Androl 1992;13:117-24.  Back to cited text no. 37
    
38.Abalovich M, Levalle O, Hermes R. Hypothalamic-pituitary-testicular axis and seminal parameters in hyperthyroid males. Thyroid 1999;9:857-63.  Back to cited text no. 38
    
39.Lei J, Nowbar S, Mariash CN, Ingbar DH. Thyroid hormone stimulates Na-K-ATPase activity and its plasma membrane insertion in rat alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2003;285:762-72.  Back to cited text no. 39
    
40.Anbalagan J, Sashi AM, Vengatesh G, Stanley JA, Neelamohan R, Aruldhas MM. Mechanism underlying transient gestational-onset hypothyroidism-induced impairment of posttesticular sperm maturation in adult rats. Fertil Steril 2010;93:2491-7.  Back to cited text no. 40
    
41.Amadi K, Nwana EJ, Otubu JA. Effect of thyroxine on the contractile responses of the vas deferens to prostaglandin E2. Arch Androl 1999;42:55-62.  Back to cited text no. 41
    
42.Choudhury S, Chainy GB, Mishro MM. Experimentally induced hypo- and hyper-thyroidism influence on the antioxidant defence system in adult rat testis. Andrologia 2003;35:131-40.  Back to cited text no. 42
    
43.Aruldhas MM, Ramalingam N, Jaganathan A, John S, Arokya M, Stanley JA, et al. Gestational and neonatal-onset hypothyroidism alters androgen receptor status in rat prostate glands at adulthood. Prostate 2010;70:689-700.  Back to cited text no. 43
    
44.Maran RR, Aruldhas MM, Udhayakumar RC, Subramanian S, Rajendiren G, Antony FF, et al. Impact of altered thyroid hormone status on prostatic glycosidases. Intl J Androl 1998;21:121-8.  Back to cited text no. 44
    
45.Mondul AM, Weinstein SJ, Bosworth T, Remaley AT, Virtamo J, Albanes D. Circulating thyroxine, thyroid stimulating hormone, and hypothyroid status and the risk of prostate cancer. PLOS One 2012;7:1-7.  Back to cited text no. 45
    
46.Ochsendorf FR. Infections in the male genital tract and reactive oxygen species. Hum Reprod Update 1999;5:399-420.  Back to cited text no. 46
    
47.Tremellen K. Oxidative stress and male infertility-A clinical perspective. Hum Reprod Update 2008;14:243-58.  Back to cited text no. 47
    
48.De Lamirande, Gagnoc C. Reactive oxygen species and human spermatozoa. II Depletion of adenosine triphosphate plays an important role in the inhibition of sperm motility. J Androl 1992;13:379-86.  Back to cited text no. 48
    
49.Gomez E, Buckingham DW, Brindle J, Lanzafame F, Irvine DS, Aitken RJ. Development of an image analysis system to moniter the retention of residual cytoplasm by human spermatozoa: Correlation with biochemical markers of the cytoplasmic space, oxidative stress, and sperm function. J Andol 1996;17:276-87.  Back to cited text no. 49
    
50.Jaya Kumar B, Khurana ML, Ammini AC, Karmarkar MG, Ahuja MM. Reproductive endocrine functions in men with primary hypothyroidism: effect of thyroxine replacement. Horm Res 1990;34:215-8.  Back to cited text no. 50
    
51.Donnelly P, White C. Testicular dysfunction in men with primary hypothyroidism; Reversal of hypogonadotrophic hypogonadism with replacement thyroxine. Clin Endocrinol 2000;52:197-201.  Back to cited text no. 51
    
52.Velazquez EM, Arata GB. Effects of thyroid status on pituitary gonadotropin and testicular reserve in men. Arch Androl 1997;38:85-92.  Back to cited text no. 52
    
53.Prasannakumar KM, Khurana ML, Ammini AC, Godbole MM, Ahuja MM. Pituitary response to luteinizing hormone releasing hormone in hypothyroidism. In: Vichanrat A, Nitiyanant W, Eastmen C, (eds). Recent Progress in Thyroidology. New Delhi: Crystal; 1987. p. 511-5.  Back to cited text no. 53
    
54.Morris PD, Malkin CJ, Channer KS, Jones TH. A mathematical comparison of techniques to predict biologically available testosterone in a cohort of 1072 men. Euro J of Endocrinol 2004;151:241-9.  Back to cited text no. 54
    
55.Tremblay RR, Dube JY. Plasma concentrations of free and nonTeBG bound testosterone in women on oral contraceptives. Contraception 1974;10:599-605.  Back to cited text no. 55
    
56.Nanjee MN, Wheeler MJ. Plasma free testosterone - Is an index sufficient? Ann Clin Biochem 1985;22:387-90.  Back to cited text no. 56
    
57.Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999;84:3666-72.  Back to cited text no. 57
    
58.Welsh TH, Kasson BG, Hsueh AW. Direct biphasic modulation of gonadotropin-stimulated testicular androgen biosynthesis by prolactin. Biol Reprod 1986;34:796-804.  Back to cited text no. 58
    
59.Kumar A, Chaturvedi PK, Mohanty BP. Hypoandrogenaemia is associated with subclinical hypothyroidism in men. Int J Androl 2006;30:14-20.  Back to cited text no. 59
    
60.Kumar A, Mohanty BP, Rani L. Secretion of testicular steroids and gonadotrophins in hypothyroidism. Andrologia 2007;39:253-60.  Back to cited text no. 60
    
61.Rochira V, Balestrieri A, Faustini-Fustini M, Borgato S, Beck-Peccoz P, Carani C. Pituitary function in a man with congenital aromatase deficiency: Effect of different doses of transdermal E2 on basal and stimulated pituitary hormones. J Clin Endocrinol Metab 2002;87:2857-62.  Back to cited text no. 61
    
62.Rochira V, Zirilli L, Genazzani AD, Balestrieri A, Aranda C, Fabre B, et al. Hypothalamic-pituitary-gonadal axis in two men with aromatase deficiency: Evidence that circulating estrogens are required at the hypothalamic level for the integrity of gonadotropin negative feedback. Eur J Endocrinol 2006;155:513-22.  Back to cited text no. 62
    
63.Boyages SC, Halpern JP. Endemic cretinism: toward a unifying hypothesis. Thyroid 1993;3:59-69.  Back to cited text no. 63
    
64.Trokoudes KM, Sugenoya A, Hazani E, Row VV, Volpe R. Thyroid-stimulating hormone (TSH) binding to extrathyroidal human tissues: TSH and thyroid-stimulating immunoglobulin effects on adenosine 3',5'-monophosphate in testicular and adrenal tissues. J Clin Endocrinol Metab 1979;48:919-23.  Back to cited text no. 64
    
65.Trummer H, Ramschak-Schwarzer S, Haas J, Habermann H, Pummer K, Leb G. Thyroid hormones and thyroid antibodies in infertile males. Fertil Steril 2001;76:254-7.  Back to cited text no. 65
    
66.Kumar A, Dewan R, Suri J, Kohli S, Shekhar S, Dhole B, et al. Abolition of endocrine dimorphism in hyperthyroid males? An argument for the positive feedback effect of hyperestrogenaemia on LH secretion. Andrologia 2012;44:217-25.  Back to cited text no. 66
    
67.Longcope C. Methods and results of aromatization studies in vivo. Cancer Res 1982;42:3307s-11.  Back to cited text no. 67
    
68.Barbarino A, Marinis LD, Mancini A. Estradiol modulation of basal and gonadotropin-releasing-hormone-induced gonadotropin release in intact and castrated men. Neuroendocrinology 1983;36:105-11.  Back to cited text no. 68
    
69.Boucekkine C, Semrouni M. Presence of positive feedback in males with Klinefelter's syndrome. Horm Res 1990;33:244-7.  Back to cited text no. 69
    
70.Karnath BM. Gynecomastia. Hosp Physician 2008;44:45-51.  Back to cited text no. 70
    


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