Impact of neonatal onset hypothyroidism on sertoli cell number, plasma andtesticular interstitial fluid androgen binding protein concentration

The impact of neonatal onset hypothyroidism from day 1 postpartum through d ifferent postnatal developmental events on rat testis was studied in vivo. Hypothyroidism was induced in neonates by feeding the lactating mother or d irectly with 0.05% methimazole (MMI) through drinking water from the day of birth and were killed at day 10, 15, 30, 40 and 60 postpartum. Hypothyroid ism was confirmed by radioimmunoassay of thyroid hormones and TSH. Sertoli cell number, plasma and testicular interstitial fluid (TIF) androgen bindin g protein (ABP) concentration was quantified. Sertoli cell number was consi stently decreased in all hypothyroid rats. Plasma ABP was also decreased ir respective of the duration of hypothyroidism. Unlike plasma ABP, TIF ABP co ncentration in hypothyroid rats increased at day 10, and 15 postpartum and decreased in other age groups. Plasma FSH level was increased significantly in all hypothyroid groups. The present investigation points out that suppr ession of T-3 during the critical period of Sertoli cell proliferation affe cts their number and functional activity.