Evidence for a GABAergic system in rodent and human testis: Local GABA production and GABA receptors

The major neurotransmitter of the central nervous system, gamma-aminobutyric acid (GABA), exerts its actions through GABA(A), GABA(B) and GABA(C) receptors. GABA and GABA receptors are, however, also present in several non-neural tissues, including the endocrine organs pituitary, pancreas and testis. In the case of the rat testis, GABA appears to be linked to the regulation of steroid synthesis by Leydig cells via GABA(A) receptors, but neither testicular sources of GABA, nor the precise nature of testicular GABA receptors are fully known. We examined these points in rat, mouse, hamster and human testicular samples. RT-PCR followed by sequencing showed that the GABA-synthesizing enzymes glutamate decarboxylase (GAD) 65 and/or GAD67, as well as the vesicular GABA transporter vesicular inhibitory amino acid transporter (VIAAT/VGAT) are expressed. Testicular GAD in the rat was shown to be functionally active by using a GAD assay, and Western blot analysis confirmed the presence of GAD65 and GAD67. Interstitial cells, most of which are Leydig cells according to their location and morphological characteristics, showed positive immunoreaction for GAD and VIAAT/VGAT proteins. In addition, several GABA(A) receptor subunits (alpha1-3, beta1-3, gamma1-3), as well as GABAB receptor subunits R1 and R2, were detected by RT-PCR. Western blot analysis confirmed the results for GABA(A) receptor subunits beta2/3 in the rat, and immunohistochemistry identified interstitial Leydig cells to possess immunoreactive GABA(A) receptor subunits beta2/3 and alpha1. The presence of GABA(A) receptor subunit alpha1 mRNA in interstitial cells of the rat testis was further shown after laser microdissection followed by RT-PCR analysis. In summary, these results describe molecular details of the components of an intratesticular GABAergic system expressed in the endocrine compartment of rodent and human testes. While the physiological significance of this peripheral neuroendocrine system conserved throughout species remains to be elucidated, its mere presence in humans suggests the possibility that clinically used drugs might be able to interfere with testicular function. Copyright (C) 2003 S. Karger AG, Basel

Involvement of tumor necrosis factor-α in the pathogenesis of autoimmune orchitis in rats

We studied the testicular macrophages of rats with experimental autoimmune orchitis (EAO) and analyzed whether the tumor necrosis factor-α (TNFα) is involved in germ cell apoptosis and in Leydig cell steroidogenesis. The EAO was induced in adult male Sprague-Dawley rats by active immunization with testicular homogenate and adjuvants. In the experimental group, a severe orchitis was observed 80 days after the first immunization. ED1- and ED2-positive macrophages were quantified by immunohistochemistry. The TNFα concentration of conditioned media from testicular macrophages (TMCM) was determined by ELISA. The number of apoptotic TNF receptor 1 (TNFR1)-positive germ cells was identified by combining in situ end labeling of apoptotic DNA and immunohistochemical techniques. The effect of TNFα on Leydig cell testosterone production was determined by RIA. In rats with EAO, we observed a significant increase in the number of TNFα-positive testicular macrophages, the TNFα concentration in TMCM, and the number of TNFR1-positive germ cells. Sixty percent of TNFR1-positive germ cells were apoptotic. These results suggest that TNFα could be involved in the pathogenesis of EAO. Acting together with other local factors such as Fas-FasL, TNFα could trigger germ cell apoptosis. We also demonstrated that TNFα inhibited in vitro testosterone production in basal and hCG-stimulated Leydig cells from rats with orchitis.Facultad de Ciencias Exacta

Involvement of tumor necrosis factor-α in the pathogenesis of autoimmune orchitis in rats

We studied the testicular macrophages of rats with experimental autoimmune orchitis (EAO) and analyzed whether the tumor necrosis factor-α (TNFα) is involved in germ cell apoptosis and in Leydig cell steroidogenesis. The EAO was induced in adult male Sprague-Dawley rats by active immunization with testicular homogenate and adjuvants. In the experimental group, a severe orchitis was observed 80 days after the first immunization. ED1- and ED2-positive macrophages were quantified by immunohistochemistry. The TNFα concentration of conditioned media from testicular macrophages (TMCM) was determined by ELISA. The number of apoptotic TNF receptor 1 (TNFR1)-positive germ cells was identified by combining in situ end labeling of apoptotic DNA and immunohistochemical techniques. The effect of TNFα on Leydig cell testosterone production was determined by RIA. In rats with EAO, we observed a significant increase in the number of TNFα-positive testicular macrophages, the TNFα concentration in TMCM, and the number of TNFR1-positive germ cells. Sixty percent of TNFR1-positive germ cells were apoptotic. These results suggest that TNFα could be involved in the pathogenesis of EAO. Acting together with other local factors such as Fas-FasL, TNFα could trigger germ cell apoptosis. We also demonstrated that TNFα inhibited in vitro testosterone production in basal and hCG-stimulated Leydig cells from rats with orchitis.Facultad de Ciencias Exacta

Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F 2α production in hamster Leydig cells

We have previously observed expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the key enzyme in the biosynthesis of prostaglandins (PGs), in reproductively active Syrian hamster Leydig cells, and reported an inhibitory role of PGF 2α on hamster testicular steroidogenesis. In this study, we further investigated PTGS2 expression in hamster Leydig cells during sexual development and photoperiodic gonadal regression. Since PTGS2 is mostly expressed in pubertal and reproductively active adult hamsters with high circulating levels of LH and androgens, we studied the role of these hormones in the regulation/maintenance of testicular PTGS2/PGF 2α. In active hamster Leydig cells, LH/hCG and testosterone induced PTGS2 and PGF 2α production, and their actions were abolished by the antiandrogen bicalutamide (Bi). These results indicate that LH does not exert a direct effect on PG synthesis. Testosterone also stimulated phosphorylation of the mitogen-activated protein kinase isoforms 3/1 (MAPK3/1) within minutes and hours, but the testosterone metabolite dihydrotestosterone had no effect on PTGS2 and MAPK3/1. Because Bi and U0126, an inhibitor of the MAP kinase kinases 1 and 2 (MAP2K1/2), abolished testosterone actions on MAPK3/1 and PTGS2, our studies suggest that testosterone directly induces PTGS2/PGF 2α in hamster Leydig cells via androgen receptors and a non-classical mechanism that involves MAPK3/1 activation. Since PGF 2α inhibits testosterone production, it might imply the existence of a regulatory loop that is setting a brake on steroidogenesis. Thus, the androgen environment might be crucial for the regulation of testicular PG production at least during sexual development and photoperiodic variations in hamsters.Instituto Multidisciplinario de Biología Celula

Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F 2α production in hamster Leydig cells

We have previously observed expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the key enzyme in the biosynthesis of prostaglandins (PGs), in reproductively active Syrian hamster Leydig cells, and reported an inhibitory role of PGF 2α on hamster testicular steroidogenesis. In this study, we further investigated PTGS2 expression in hamster Leydig cells during sexual development and photoperiodic gonadal regression. Since PTGS2 is mostly expressed in pubertal and reproductively active adult hamsters with high circulating levels of LH and androgens, we studied the role of these hormones in the regulation/maintenance of testicular PTGS2/PGF 2α. In active hamster Leydig cells, LH/hCG and testosterone induced PTGS2 and PGF 2α production, and their actions were abolished by the antiandrogen bicalutamide (Bi). These results indicate that LH does not exert a direct effect on PG synthesis. Testosterone also stimulated phosphorylation of the mitogen-activated protein kinase isoforms 3/1 (MAPK3/1) within minutes and hours, but the testosterone metabolite dihydrotestosterone had no effect on PTGS2 and MAPK3/1. Because Bi and U0126, an inhibitor of the MAP kinase kinases 1 and 2 (MAP2K1/2), abolished testosterone actions on MAPK3/1 and PTGS2, our studies suggest that testosterone directly induces PTGS2/PGF 2α in hamster Leydig cells via androgen receptors and a non-classical mechanism that involves MAPK3/1 activation. Since PGF 2α inhibits testosterone production, it might imply the existence of a regulatory loop that is setting a brake on steroidogenesis. Thus, the androgen environment might be crucial for the regulation of testicular PG production at least during sexual development and photoperiodic variations in hamsters.Instituto Multidisciplinario de Biología Celula

A Ca2+-activated potassium channel (BKCa) in Leydig cells is involved in testosterone production

Previously, we found that human steroid-producing ovarian granulosa cells express all major types of Ca2+-activated potassium channels (KCa), including BKCa, IK and SKs (Traut et al., RB&E, 2009), and that modulation of the activity of these channels resulted in alteration of steroid production. In the male gonad Leydig cells produce androgens, but whether these cells are endowed with KCas is not known. We addressed these points and focussed on BKCa, which is Ca2+-activated and the underlying channel for a prominent current. It can be manipulated, e.g. by a specific blocker, the red scorpion toxin iberiotoxin (IbTx), which binds to the outer face with high affinity and selectively inhibits the current by decreasing both the probability of opening and the open time of the channel.Fil: Siebert, S. Ludwig Maximilians Universität München. ; AlemaniaFil: Spinnler, K. Ludwig Maximilians Universität München. ; AlemaniaFil: Matzkin, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Kunz, L. Ludwig Maximilians Universität München. ; AlemaniaFil: Calandra, Ricardo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Frungieri, Monica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Mayerhofer, A. Ludwig Maximilians Universität München. ; Alemania22. Jahrestagung der Deutschen Gesellschaft für Andrologie e VHamburgoAlemaniaDeutsche Gesellschaft für AndrologieConventus Congressmanagement und Marketing Gmb

Involvement of tumor necrosis factor-α in the pathogenesis of autoimmune orchitis in rats

We studied the testicular macrophages of rats with experimental autoimmune orchitis (EAO) and analyzed whether the tumor necrosis factor-α (TNFα) is involved in germ cell apoptosis and in Leydig cell steroidogenesis. The EAO was induced in adult male Sprague-Dawley rats by active immunization with testicular homogenate and adjuvants. In the experimental group, a severe orchitis was observed 80 days after the first immunization. ED1- and ED2-positive macrophages were quantified by immunohistochemistry. The TNFα concentration of conditioned media from testicular macrophages (TMCM) was determined by ELISA. The number of apoptotic TNF receptor 1 (TNFR1)-positive germ cells was identified by combining in situ end labeling of apoptotic DNA and immunohistochemical techniques. The effect of TNFα on Leydig cell testosterone production was determined by RIA. In rats with EAO, we observed a significant increase in the number of TNFα-positive testicular macrophages, the TNFα concentration in TMCM, and the number of TNFR1-positive germ cells. Sixty percent of TNFR1-positive germ cells were apoptotic. These results suggest that TNFα could be involved in the pathogenesis of EAO. Acting together with other local factors such as Fas-FasL, TNFα could trigger germ cell apoptosis. We also demonstrated that TNFα inhibited in vitro testosterone production in basal and hCG-stimulated Leydig cells from rats with orchitis.Facultad de Ciencias Exacta

Hormonal Regulation of Follicle-Stimulating Hormone Glycosylation in Males

The Follicle-Stimulating Hormone plays an important role in the regulation of gametogenesis. It is synthesized and secreted as a family of glycoforms with differing oligosaccharide structure, biological action, and half-life. The presence of these oligosaccharides is absolutely necessary for the full expression of hormone bioactivity at the level of the target cell. The endocrine milieu modulates the glycosylation of this hormone. During male sexual development a progressive increase in FSH sialylation and in the proportion of glycoforms bearing complex oligosaccharides are the main features in this physiological condition. In late puberty, FSH oligosaccharides are largely processed in the medial- and trans-Golgi cisternae of the gonadotrope and remain without changes throughout adult life. In experimental models, the absence of gonads severely affects FSH sialylation; androgen administration is able to restore the characteristics observed under physiological conditions. The expression of ST6 beta-galactoside alpha-2,6-sialyltransferase 1 is hormonally regulated in the male rat; it decreases after short periods of castration but increases markedly at longer periods of androgen deprivation. Although ST3 beta-galactoside alpha-2,3-sialyltransferase 3 is expressed in the male rat pituitary it is not influenced by changes in the endocrine milieu. The oligosaccharide structure of FSH has an impact on the Sertoli cell endocrine activity. In more advanced stages of Sertoli cell maturation, both sialylation and complexity of the oligosaccharides are involved in the regulation of inhibin B production; moreover, FSH glycoforms bearing incomplete oligosaccharides may enhance the stimulatory effect exerted by gonadal growth factors. In this review, we discuss available information on variation of FSH glycosylation and its hormonal regulation under different physiological and experimental conditions, as well as the effect on Sertoli cell endocrine activity

Expression of the TGF-beta1 system in human testicular pathologies

In non-obstructive azoospermia, histological patterns of Sertoli cell-only Syndrome (SCO) and hypospermatogenesis (H) are commonly found. In these pathologies, Leydig cell hyperplasia (LCH) is detected in some patients. Since TGF-β1 is involved in cellular proliferation/development, the aim of this work was to analyze the expression of TGF-β1, its receptors TGFBRII, TGFBRI (ALK-1 and ALK-5), and the co-receptor endoglin in human biopsies from patients with idiopathic infertilityFil: Gonzalez, Candela Rocio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Matzkin, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Frungieri, Monica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Terradas, Claudio. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos"Carlos G. Durand"; Argentina. Instituto Médico IPREFER; ArgentinaFil: Ponzio, Roberto . Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Puigdomenech, Elisa. Instituto Médico IPREFER;; ArgentinaFil: Levalle, Oscar. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos"Carlos G. Durand"; ArgentinaFil: Calandra, Ricardo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina; ArgentinaFil: Gonzalez Calvar, Silvia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentin

Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F 2α production in hamster Leydig cells

We have previously observed expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the key enzyme in the biosynthesis of prostaglandins (PGs), in reproductively active Syrian hamster Leydig cells, and reported an inhibitory role of PGF 2α on hamster testicular steroidogenesis. In this study, we further investigated PTGS2 expression in hamster Leydig cells during sexual development and photoperiodic gonadal regression. Since PTGS2 is mostly expressed in pubertal and reproductively active adult hamsters with high circulating levels of LH and androgens, we studied the role of these hormones in the regulation/maintenance of testicular PTGS2/PGF 2α. In active hamster Leydig cells, LH/hCG and testosterone induced PTGS2 and PGF 2α production, and their actions were abolished by the antiandrogen bicalutamide (Bi). These results indicate that LH does not exert a direct effect on PG synthesis. Testosterone also stimulated phosphorylation of the mitogen-activated protein kinase isoforms 3/1 (MAPK3/1) within minutes and hours, but the testosterone metabolite dihydrotestosterone had no effect on PTGS2 and MAPK3/1. Because Bi and U0126, an inhibitor of the MAP kinase kinases 1 and 2 (MAP2K1/2), abolished testosterone actions on MAPK3/1 and PTGS2, our studies suggest that testosterone directly induces PTGS2/PGF 2α in hamster Leydig cells via androgen receptors and a non-classical mechanism that involves MAPK3/1 activation. Since PGF 2α inhibits testosterone production, it might imply the existence of a regulatory loop that is setting a brake on steroidogenesis. Thus, the androgen environment might be crucial for the regulation of testicular PG production at least during sexual development and photoperiodic variations in hamsters.Instituto Multidisciplinario de Biología Celula