Syed G. Haider

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.

Trends of Reproductive Hormones in Male Rats During Psychosocial Stress: Role of Glucocorticoid Metabolism in Behavioral Dominance

Abstract Stress in socially subordinate male rats, associated with aggressive attacks by dominant males, was studied in a group-housing context called the visible burrow system (VBS). It has been established that subordinate males have reduced serum testosterone (T) and higher corticosterone (CORT) relative to dominant and singly housed control males. The relationship of the decreased circulating T levels in subordinate males to changes in serum LH concentrations has not been evaluated previously. Since decreases in LH during stress may cause reductions in Leydig cell steroidogenic activity, the present study defined the temporal profiles of serum LH, T, and CORT in dominant and subordinate males on Days 4, 7, and 14 of a 14-day housing period in the VBS. The same parameters were followed in serum samples from single-housed control males. Leydig cells express glucocorticoid receptors and may also be targeted for direct inhibition of steroidogenesis by glucocorticoid. We hypothesize that Leydig cells are protected from inhibition by CORT at basal concentrations through oxidative inactivation of glucocorticoid by 11β-hydroxysteroid dehydrogenase (11βHSD). However, Leydig cell steroidogenesis is inhibited when 11βHSD metabolizing capacity is exceeded. Therefore, 11βHSD enzyme activity levels were measured in Leydig cells of VBS-housed males at the same time points. Significant increases in LH and T relative to control were observed in the dominant animals on Day 4, which were associated with the overt establishment of behavioral dominance as evidenced by victorious agonistic encounters. Serum LH and T were lower in subordinate males on Day 7, but T alone was lower on Day 14, suggesting that lowered LH secretion in subordinates may gradually be reversed by declines in androgen-negative feedback. Serum CORT levels were higher in subordinate males compared to control at all three time points. In contrast, oxidative 11βHSD activity in Leydig cells of dominant males was higher relative to control and unchanged in subordinates. These results suggest the following: 1) failure of Leydig cells of subordinate males to compensate for increased glucocorticoid action during stress, by increasing 11βHSD oxidative activity, potentiates stress-mediated reductions in T secretion; and 2) an inhibition of the reproductive axis in subordinate males at the level of the pituitary.

Ultracytochemistry of 3β-hydroxysteroid dehydrogenase in Leydig cell precursors and vascular endothelial cells of the postnatal rat testis

Abstract In the biosynthesis of steroid hormones 3β-hydroxysteroid dehydrogenase (3β-HSD) is a key enzyme. The present report describes the subcellular localization of the enzyme in the fetal-type Leydig cells, the fibroblast-like precursors of adult-type Leydig cells and in endothelial cells of interstitial capillaries. Histochemical methods for light microscopy and ultracytochemical methods for electron microscopy were used on rat testes of postnatal day 15. 3β-HSD reactivity was located at subcellular levels by means of the ferricyanide method. A specific, distinct localization of reaction product in the form of copper ferrocyanide precipitates was observed on the membranes of the smooth endoplasmic reticulum not only in the fetal-type Leydig cells and the fibroblast-like precursors of adult-type Leydig cells, but also focally in the endothelial cells of interstitial blood capillaries. Topographically, the 3β-HSD-positive precursors were most often found in the outer layer of the boundary tissue and surrounding interstitial blood vessels. The capillaries with 3β-HSD-positive endothelial cells were usually located in the vicinity of 3β-HSD-positive Leydig cells. For the first time, 3β-HSD has been located at the subcellular level in precursors of adult-type Leydig cells and focally in capillary endothelial cells associated with them. Due to the close association between 3β-HSD-positive vascular endothelial cells and Leydig cells a paracrine relationship between the two cell types may be involved in the acute regulation of steroidogenesis by blood-borne luteinizing hormone.

Morphine induces reproductive changes in female rats and their male offspring

The effect of intrauterine morphine exposure on the development of reproductive functions has been investigated in the rat. Female rats were treated daily ip with morphine sulfate, doses increasing at 10-d intervals from 5, 7.5, 10, to 15 mg/kg. These rats were mated between day 38 and 45, and morphine treatment continued at 20 and 30 mg/kg over pregnancy and at up to 40 mg/kg for 10 d postpartum. The treatment mainly disrupted ovarian cyclicity; only 48% exhibited normal cyclicity. Of these, 43% became pregnant when mature male rats were placed with them. Litter size was normal but with significantly more stillbirths in each litter and live pups had decreased body weights. Male offspring had reduced body weight at the time of weaning that persisted until 60 d of age. At 120 d, animals showed complete abolition of spermatogenesis and drastically reduced testicular steroidogenesis. Plasma LH levels were low, and hypothalamic noradrenaline was high.

Ontogenesis of Oxidative Reaction of 17β-hydroxysteroid Dehydrogenase and 11β-hydroxysteroid Dehydrogenase in Rat Leydig Cells, a Histochemical Study

The enzyme 17β-hydroxysteroid dehydrogenase is required for the synthesis and 11β-hydroxysteroid dehydrogenase for the regulation of androgens in rat Leydig cells. This histochemical study describes ontogenetic changes in distribution and intensity of these enzymes in Leydig cells from postnatal day (pnd) 1–90. Using NAD or NADP as the cofactor, 17β-hydroxysteroid dehydrogenase (substrate: 5-androstene-3β, 17β-diol) peaks were observed on pnd 16 for fetal Leydig cells and on pnd 19 and 37 for adult Leydig cells. Between pnd 13 and 25 the fetal cells showed a higher intensity for the 17β-enzyme than the adult cells; more fetal Leydig cells were stained with NADP, whereas more adult cells were positive with NAD on pnd 13 and 16. A nearly identical distribution of 11β-hydroxysteroid dehydrogenase (substrate: corticosterone) was observed with NAD or NADP as the cofactor; the reaction was present from pnd 31 onwards, first in a few adult Leydig cells and later in almost all these cells homogeneously. The ontogenetic curves of the two enzymes show an inverse relationship. To conclude: (1) Generally, a stronger reaction for 17β-hydroxysteroid dehydrogenase is shown with NAD as cofactor than with NADP; using NADP, fetal Leydig cells show a stronger staining than adult Leydig cells. (2) The data possibly support the notion of a new isoform of 11β -hydroxysteroid dehydrogenase in addition to types 1 and 2.

Sites of action of gossypol studied by autoradiography and enzyme histochemistry.

The distribution of 14C-gossypol acetate was studied by autoradiography in male rats after intraperitoneal or intratesticular injection. Accumulation of radioactivity was found in testis, kidney and liver, while there was little in brain, pituitary and epididymis. In testis, high accumulation occurred in interstitial cells, with low levels in Sertoli cells, spermatogonia and spermatocytes. In addition, the chronic effect of gossypol was assessed by enzyme histochemistry with thiamine pyrophosphate, alpha-glycerophosphate dehydrogenase, and by lipid stain. In the treated animals an increased number of luminal exfoliated cells (Sertoli cells, germ cells and spermatids) was noted, which showed positive reactions. The results suggest both direct and indirect effects of gossypol on testicular functions.

Ultrastructure of cell contacts of fetal and adult Leydig cells in the rat: a systematic study from birth to senium

Differentiation, development, and function of Leydig cells in the testis are regulated also by macrophages, vascular endothelial cells, and peritubular cells in the testis. The aim of the present study was to investigate the possible morphological substrates for communication between these cells. The cell contacts between adjacent Leydig cells, and between Leydig cells and other interstitial cells were studied electron microscopically in the rat testis of various age groups from birth to senium. Intercellular bridges with continuous cytoplasm were observed between fetal Leydig cells (FLCs) in the early postnatal period. Gap junctions were present in nearly every age group. A structural diversity as well as an increased occurrence of gap junctions with the maturity of the Leydig cells was noted. Coated pits were observed initially on pnd 30. From pnd 50 onwards, macrophages and Leydig cells were attached very closely to each other, when the cell processes of Leydig cells protruded either into the coated pits or into the deep invaginations of macrophages. To conclude, this is the first report on the presence of intercellular bridges between FLCs suggesting a possible functional synchronization of interconnected Leydig cells. The cell contacts observed here are possibly required for a precise communication between the Leydig cells and other interstitial cells.

Description of eight phases of spermiogenesis in the marmoset testis

The differentiation of spermatids in the marmoset (Callithrix jacchus, n = 9) testis is described here at the light-microscopic level employing serial semithin sections. The definition of 8 different phases of spermiogenesis, i.e. the formation of spermatids, is based upon the changes in the development of nucleus, acrosome and flagellum.

Mg2+-ATPase activity in the rat testis and its correlation with the stages of spermatogenesis: a histochemical study

SummaryThe activity of Mg2+-activated ATPase was studied in the rat testis employing histochemical and microphotometrical methods. The enzymatic activity could be correlated with the stages of spermatogenesis. From stage XII onwards, the elongated spermatids showed a weak to moderate activity, which increased from the acrosomal phase to the, maturation phase. The reaction product was located in the mid-piece and tail piece of elongated spermatids with a maximum intensity at stage VIII. Morphometric analysis revealed six distinct patterns, which could be correlated with the stages of spermatogenesis.

Demonstration of hydroxysteroid dehydrogenases and testosterone in the Sertoli-Leydig cell tumor (androblastoma) tissue of the human ovary: an enzyme histochemical and immunohistochemical study

Gynecological, endocrinological and histological tests on a 19-year-old female patient led to the diagnosis of Sertoli-Leydig cell tumor (arrhenoblastoma) of intermediate differentiation. For enzyme histochemical purposes the tumor tissue, removed from the right ovary by laparatomy, was frozen in liquid nitrogen. The following enzymes were demonstrated: nonspecific esterases, 3 beta-hydroxysteroid dehydrogenase (HSDH), 17 beta-HSDH, 11 beta-HSDH, and NADH tetrazolium reductase. Cryostat sections, prefixed with formaldehyde vapors, were used to localize testosterone production immunohistochemically with the PAP method. A large number of pseudotubules with Sertoli cells were observed; the Leydig cells in the interstitial space were often arranged in the form of islands. Strong nonspecific esterase activity weak 3 beta-HSDH activity, moderate 17 beta-HSDH activity, and strong 11 beta-HSDH activity were observed largely in the Leydig cells. Testosterone synthesis, demonstrated immunohistochemically, took place predominantly in the Leydig cells, but also to a small extent in the Sertoli cells.