Age-dependence of the rat Leydig cell and Sertoli cell function.

Abstract

Abstract. The first part of this study compares peripheral testosterone levels with intratesticular levels of the cytochromes P-450 of two key enzymes of androgen biosynthesis, i.e. mitochondrial cholesterol monooxygenase (P-450(cscc)) and microsomal steroid-17α-monooxygenase (P-450(C17α)) during puberty and early adulthood of male Wistar rats. From 4 to 10 weeks of age, the testosterone level increases 8.7-fold, the P-450(C17α) level 8.3-fold, but the P-450(cscc) level 24.5-fold as an indication of specific induction of this protein. From 13 to 50 weeks of age, the testosterone level remains constant, the P-450(cscc) level increases continuously by a factor of 1.4, but 62% of the P-450(C17α) content are lost. This discrepancy is explained by a divergent regulation of the cytochromes P-450 of the two steroid monooxygenases: a persisting induction of P-450(cscc) and a concurrent down-regulation of P-450(C17α) that may be a consequence of the high rate of Leydig cell steroid hydroxylation after puberty. Overlapping of both processes may (probably besides other developmental factors) result in a constant testosterone concentration in blood. The second part of the study compares testicular and epididymal levels of androgen-binding protein (ABP) with the peripheral testosterone level. The peripubertal increase in testicular ABP content is shown to be related only to the increase in testicular mass, whereas a specific accumulation of ABP occurs in the epididymis from 4 to 13 weeks of age. This pattern indicates an increasing secretory activity of the Sertoli cells that remains high during adulthood up to the 50th week. The parallelity of epididymal ABP accumulation and testosterone level confirms the concept of androgen-dependence of Sertoli cell secretory function.

Thyroid hormone affects the development of Sertoli cell function in the rat

“…Hypothyroidism, when induced soon after birth, resulted in a severe retardation in the growth of body and testis. Therefore, in 28-day-old rats treated with MMI the GSI, which is known to increase during puberty (Kühn-Veiten, Bos, Schermer & Staib, 1987) and can be interpreted as a marker for gonadospecific growth, was markedly lower in comparison with the controls of the same age and approached that of 15-day-old rats. Perinatal hypothyroidism resulted in a net inhibition of the increase in GGT activity as well as in ABP and lactate production which normally occurs during postnatal development of Sertoli cells.…”

A Light and Scanning Electron Microscopic Study of the Epididymis Active State of the Endemic Mexican Rodent Peromyscus winkelmanni (Carleton) (Rodentia: Muridae)

“…The testes and right epididymides were dissected, and testicular diameters (cranial–caudal, anterior–posterior and medial–lateral) were measured. The weights of the specimens were compared through the gonadosomatic index (Kuhn‐Velten et al., 1987). Five testis and epididymides were processed for light microscopy studies and two epididymides were processed for scanning electron microscopic analysis.…”

Classic and Novel Sex Hormone Binding Globulin Effects on the Cardiovascular System in Men

“…Additionally, SHBG mRNAs exhibit alternative splicing that encodes the androgen-binding protein (ABP) [22,53], which differs from SHBG mRNAs by the presence of an exon I (exon A) that does not influence the post-translational modifications required for SHBG secretion [54]. In humans and rats, ABP is produced in the liver [22], Sertoli and Leydig cells [55], and cardiomyocytes [31,56]. e physiological role of ABPs in peripheral tissues remains poorly understood; however, studies indicate that ABPs regulate the local bioavailability of androgens [56][57][58].…”