Duration-Dependent Effect of Transient Neonatal Hypothyroidism on Sertoli and Germ Cell Number, and Plasma and Testicular Interstitial Fluid Androgen Binding Protein Concentration

Abstract

The impact of transient neonatal hypothyroidism on growth and function of puberal testis during different milestones of postnatal testicular development was studied in Wistar rats. Rat pups were made hypothyroid for 10, 15, 30, 40 and 60 days of postnatal age from birth by providing 0.05% (W/V) methimazole (MMI) in the drinking water of the mother, from day 1 postpartum till weaning (25 days postpartum) and thereafter in the drinking water. Control rats were raised without MMI treatment. Sertoli cell number and its function was assessed on day 60 postpartum. Sertoli cell number increased consistently in 10, 15, 30 and 40 days transient hypothyroid rats but decreased in rats subjected to continuous hypothyroidism from birth to 60 days postpartum. Rats subjected to continuous hypothyroidism from birth showed spermatogenic arrest at puberty and had only a single layer of spermatogonia. Transient neonatal hypothyroidism for 10 (or) 15 days from birth increased spermatocytes (pachytene and zygotene), spermatids (elongated and round) whereas, that of 30 and 40 days decreases the number of germ cells. Plasma androgen binding protein (ABP) concentration decreased in puberal rats belonging to all groups, whereas the testicular interstitial fluid (TIF) concentration of ABP increased significantly in 10 and 15 days hypothyroid rats while it decreased in all other groups. These findings indicate that the mitogenic activity of Sertoli cell is increased irrespective of the duration of transient neonatal hypothyroidism. However, the functional activity of Sertoli cells (ABP production) in these puberal rats varies depending upon the postnatal period at which the animals were in hypothyroid state.

Thyroid Hormones: Their Role in Testicular Steroidogenesis

“…[20,69,78]. Transient neonatal hypothyroidism initially increased plasma and TIF ABP levels, but prolonged hypothyroidism caused a decrease in mRNA expression and TIF ABP levels [20,70].…”

Mechanism underlying transient gestational-onset hypothyroidism–induced impairment of posttesticular sperm maturation in adult rats

“…Transient neonatal hypothyroidism in rats boosts spermatogenesis and alters androgen: estrogen ratio at puberty and adulhood (1)(2)(3)(4). Male fertility is determined by spermatogenesis and steroidogenesis in the testis and posttesticular sperm maturation in the epididymis, where spermatozoa undergo physiologic, morphologic, and biochemical changes that provide them forward motility and fertilizing ability (5,6).…”

Effects of Propylthiouracil on Testicular Tissue in Undescended Testes of Newborn Rats

“…In case of severe hypothyroidism a reduction in Leydig cells is seen but in moderate hypothyroidism the number of these cells increases [9] . Transient neonatal hypothyroidism leads to a rise in androgen-binding proteins in plasma and testicular interstitial fl uid, but in protracted cases exactly the reverse effect can be observed [10,11] . To make use of this phenomenon we administered PTU to prepubertal and neonatal rats with experimental UTs to show the benefi cial effects in ameliorating testicular damage.…”