Maran R R M, Aruldhas M M
Department of Endocrinology, Dr. ALM. P. G. Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai 600 113, India.
Endocr Res. 2002 Aug;28(3):141-54. doi: 10.1081/erc-120015051.
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.
在不同年龄组的Wistar大鼠中研究了新生儿甲状腺功能减退对精子发生的影响。从产后第1天到产后第60天，通过每天给哺乳的母鼠或直接通过饮水给予0.05%的甲巯咪唑（MMI），诱导新生雄性大鼠发生甲状腺功能减退。在产后第10、15、30、40和60天处死动物，收集血浆，并分离和称重睾丸、附睾、前列腺和精囊。将睾丸固定在福尔马林中用于组织学研究。通过放射免疫测定法测量血浆睾酮（T）、雌二醇（E2）和性激素结合球蛋白（SHBG）。甲状腺功能减退显著降低了生精小管和管腔直径。对照大鼠显示出活跃的精子发生，而在甲状腺功能减退的大鼠中，生殖细胞的增殖和分化停滞，其数量减少。甲状腺功能减退大鼠在所有年龄段的血浆T、E2和SHBG水平均显著降低。无论年龄如何（产后第10天除外），睾丸的绝对重量均降低，然而，在产后第30、40和60天，腹侧、背外侧前列腺和附睾的重量降低。甲状腺功能减退大鼠的所有年龄组中，凝固腺重量均降低。产后第40和60天的甲状腺功能减退大鼠精囊绝对重量降低。甲状腺功能减退大鼠的相对睾丸重量在产后第15、30、40和60天降低，而在产后第10天观察到相反的效果。附睾（产后第15和30天）、精囊（产后第30和40天）和背外侧前列腺（产后第15、30和40天）的相对器官重量增加，而10日龄和60日龄甲状腺功能减退大鼠的相对器官重量降低。40日龄和60日龄大鼠腹侧前列腺相对重量降低。产后第10、15和60天凝固腺重量降低，而在产后第30和40天的甲状腺功能减退大鼠中观察到相反的效果。本研究清楚地表明，甲状腺功能减退对精子发生有不利影响；它还表明甲状腺激素对正常精子发生至关重要。它们的作用可能是直接的或间接的。
