Ontogenesis of oxidative reaction of 17beta-hydroxysteroid dehydrogenase and 11beta-hydroxysteroid dehydrogenase in rat Leydig cells, a histochemical study

Protein carbonyl, 3β-, and 17β-hydroxysteroid dehydrogenases in testes and serum FSH, LH, and testosterone levels in zinc deficient Wistar rats

The present study evaluated protein oxidation, alteration in hydroxysteroid dehydrogenases (3β- and 17β HSD) in testes and serum hormonal profiles of dietary zinc deficient Wistar rats. Pre-pubertal rats were divided into three groups: zinc control (ZC), pairfed (PF), and zinc deficient (ZD) and fed 100 ppm (ZC and PF groups) and 1.0 ppm (ZD group) zinc diet for 2- and 4-weeks. The testes from zinc deficient groups exhibited significant increase in total protein (2 weeks) and protein carbonyl (2- and 4-weeks) concentration as well as 3β- and 17β-hydroxysteroid dehydrogenase activities (4 weeks), whereas a significant decrease was recorded in total protein (testes 4 weeks; serum 2- and 4-weeks), total zinc (testes and serum 2- and 4-weeks), 3β- and 17β-hydroxysteroid dehydrogenase activities (testes 2 weeks), and serum hormonal profiles (FSH and testosterone 2- and 4-weeks). However, LH was below the detectable limits. These results reflect that zinc deficiency during pre-pubertal period affected total protein and zinc status, elevates protein oxidation, and causes dysregulation of the hydroxysteroid dehydrogenases. Low level of zinc attenuated the gonadal physiology which indicates that the metabolic regulation of testes is mediated by combined effects of a specific response (caused by decreased zinc concentration) and a nonspecific response (inhibition of gonadotrophin secretion). All these contribute to testicular dysfunction.

Cell biology of Leydig cells in the testis

This article reviews results on differentiation, structure, and regulation of Leydig cells in the testes of rodents and men. Two different populations-fetal and adult Leydig cells-can be recognized in rodents. The cells in these two populations are different in ultrastructure, life span, capacity for androgen synthesis, and mechanisms of regulation. A brief survey on the origin, ontogenesis, characterization of precursors, ultrastructure, and functional markers of fetal and adult Leydig cells is presented, followed by an analysis of genes in Leydig cells and the role of luteinizing hormone and its receptor, steroidogenic acute regulatory protein, hydroxysteroid dehydrogenases, androgen and its receptor, anti-Müllerian hormone, estrogens, and thyroid hormones. Various growth factors modulate Leydig cell differentiation, regeneration, and steroidogenic capacity, for example, interleukin 1alpha, transforming growth factor beta, inhibin, insulin-like growth factors I and II, vascular endothelial growth factor, and relaxin-like growth factor. Retinol and retinoic acid increase basal testosterone secretion in adult Leydig cells, but decrease it in fetal Leydig cells. Resident macrophages in the interstitial tissue of the testis are important for differentiation and function of Leydig cells. Apoptosis of Leydig cells is involved in the regulation of Leydig cell number and can be induced by cytotoxins. Characteristics of aging Leydig cells in rodents seem to be species specific. 11beta-hydroxysteroid dehydrogenase protects testosterone synthesis in the Leydig cells of stressed rats. Last, the following aspects of human Leydig cells are briefly described: origin, differentiation, triphasic development, aging changes, pathological changes, and gene mutations leading to infertility.

Differentiation-dependent expression of 17beta-hydroxysteroid dehydrogenase, type 10, in the rodent testis: effect of aging in Leydig cells

Expression of the new 17beta-hydroxysteroid dehydrogenase (HSD), type 10 (17beta-HSD-10), formerly known as endoplasmic reticulum-associated amyloid-binding protein, has been investigated in the testes of various mammals under normal and perturbed conditions. Results show that 17beta-HSD-10 is a major product of both fetal and adult-type Leydig cells. In the former, protein persists until late in postnatal development; and in the short-day hamster model, it does not disappear when Leydig cells involute. During puberty in the rat, immunohistochemical staining for 17beta-HSD-10 in adult-type Leydig cells first becomes evident on d 20, increasing to maximal staining intensity by d 35. In the rat, but not in the mouse or any other species examined, there is also staining in late spermatids. Examination of testes from rats subjected to perinatal treatment with either a GnRH antagonist or low and high doses of diethylstilbestrol revealed that expression of 17beta-HSD-10 follows closely Leydig cell differentiation status, correlating with 3beta-HSD expression in a previous study. In aging (23 months) rat testes, Leydig cell (but not germ cell) immunostaining for 17beta-HSD-10 is markedly reduced. 17beta-HSD-10 seems to preferentially convert 3alpha-androstanediol into dihydrotestosterone, and estradiol to estrone. Thus, perinatal expression of this enzyme in fetal Leydig cells may contribute to protecting these cells from estrogens and encourage androgen formation.