Adverse Effects of Neonatal Hypothyroidism on Wistar Rat Spermatogenesis

Abstract

The effect of neonatal hypothyroidism on spermatogenesis was studied in Wistar rats of different age groups. Hypothyroidism was induced in newborn male rats from day one postpartum up to day 60 postpartum by daily administration of 0.05% methimazole (MMI) to the nursing mothers or directly through drinking water. The animals were killed at days 10, 15, 30, 40, and 60 postpartum, blood plasma was collected, and testes, epididymides, prostates, and seminal vesicles were separated and weighed. Testes were fixed in formalin for histological studies. Plasma testosterone (T), estradiol (E2), and sex hormone binding globulin (SHBG) were measured by radioimmunoassay. Hypothyroidism significantly reduced seminiferous tubule and lumen diameter. Control rats showed active spermatogenesis whereas in hypothyroid rats, the proliferation and differentiation of germ cells were arrested and their number was decreased. Plasma T, E2, and SHBG levels were significantly decreased at all ages for hypothyroid rats. The absolute weight of testes was decreased irrespective of age (except day 10 postpartum), however ventral, dorsolateral prostate, and epididymis weights were decreased at 30, 40, and 60 days postpartum. Coagulating gland weight was decreased in all age groups of hypothyroid rats. Hypothyroid rats of day 40 and 60 postpartum showed a decrease in absolute seminal vesicle weight. Relative testicular weights of hypothyroid rats decreased by postpartum day 15, 30, 40, and 60 whereas the opposite effect was observed by postpartum day 10. Relative organ weights were increased in epididymides (day 15 and 30 postpartum), seminal vesicles (day 30 and 40 postpartum), and dorsolateral prostates (day 15, 30, and 40 postpartum) and decreased in 10 and 60 day old hypothyroid rat. Ventral prostate relative weight was decreased in 40 and 60 day old rats. Th coagulating gland weight was decreased in 10, 15, and 60 days postpartum and an opposite effect was observed in 30 and 40 days hypothyroid rats. The present study clearly indicates that hypothyroidism adversely affects spermatogenesis; it also indicates that thyroid hormones are essential for normal spermatogenesis. Their effect may either be direct or indirect.

Is there a role for thyroid hormone on spermatogenesis?

“…In addition to the histological changes, reduced serum testosterone levels were observed in both the rat models. Accordingly, prolonged hypothyroidism induced in rats by either propyl-2-thiouracyl or methimazole treatment was also shown to arrest proliferation and differentiation of germ cells, resulting in a significant decrease in germ cell number and in the percentage of live sperm in the epididymis (Maran and Aruldhas, 2002;Sahoo et al, 2007).…”

“…For instance, TRa1 expression was very high in Sertoli cell nuclei during their proliferative phase, from postnatal days 0 to 15, and subsequently declined markedly with the cessation of proliferation, remaining very low in adulthood. Interestingly, around postnatal day 15, TRa1 was found to be expressed in spermatogenic germ cells, from intermediate spermatogonia to mid-cycle pachytene spermatocytes, and also in Sakai et al, 2004Oncu et al, 2004Maran and Aruldhas, 2002 residual bodies being phagocytosed by Sertoli cells. Functional TR isoforms were also identified in the interstitial compartment of the immature testis, although it was not clear, at that point, in which specific cell types they were expressed (Buzzard et al, 2000).…”

Effect of Selenium on Carbimazole-Induced Histopathological and Histochemical Alterations in Prostate of Albino Rats

“…Also, it significantly decreased serum T 4 level. Maran and Aruldhas [24] reported that daily administration of 0.05% methimazole to the nursing mothers induced many changes in newborn male rats; significantly reduced seminiferous tubules diameter, the proliferation and differentiation of germ cells were arrested and their number were decreased.…”

Thyroid hormone regulation of mRNAs encoding thyrotropin β-subunit, glycoprotein α-subunit, and thyroid hormone receptors α and β in brain, pituitary gland, liver, and gonads of an adult teleost, Pimephales promelas

“…In mammals, THs have been shown to regulate Sertoli cell proliferation leading to changes in testis development and, subsequently, sperm production after sexual maturity (Cooke et al 1991, Francavilla et al 1991, Maran & Arudhas 2002. The effects of THs on the mammalian testis appear mediated in part via TR-regulated pathways, since knockout of tra1 leads to elevated Sertoli cell number, increased testis mass, and heightened daily sperm production (Holsberger et al 2005).…”