Affect Leydig Cell Function Research Articles

Triclosan inhibits testosterone biosynthesis in adult rats via inducing m6A methylation-mediated autophagy

Triclosan is a potent antibacterial compound widely used in everyday products. Whether triclosan affects Leydig cell function in adult male rats remains unknown. In this study, 0, 50, 100, or 200 mg/kg/day triclosan was gavaged to Sprague-Dawley male rats from 56 to 63 days postpartum. Triclosan significantly reduced serum testosterone levels at ≥ 50 mg/kg/day via downregulating the expression of Leydig cell gene Lhcgr, Scarb1, Star, Cyp11a1, Hsd3b1, Cyp17a1, and Hsd17b3 and regulatory transcription factor Nr3c2 at 100–200 mg/kg. Further analysis showed that triclosan markedly increased autophagy as shown by increasing LC3II and BECN1 and decreasing SQSTM1. The mRNA m6A modification analysis revealed that triclosan significantly downregulated Fto expression at 200 mg/kg while upregulating Ythdf1 expression at 100 and 200 mg/kg, leading to methylation of Becn1 mRNA as shown by MeRIP assay. Triclosan significantly inhibited testosterone output in rat R2C Leydig cells at ≥ 5 μM via downregulating Fto and upregulating Ythdf1. SiRNA Ythdf1 knockdown can reverse triclosan-mediated mitophagy in R2C cells, thereby reversing the reduction of testosterone output. In summary, triclosan caused Becn1 m6A methylation by downregulating Fto and upregulating Ythdf1, which accelerated Becn1 translation, thus leading to the occurrence of autophagy and the decrease of testosterone biosynthesis.

Diabetes Type 1 Negatively Influences Leydig Cell Function in Rats, Which is Partially Reversible By Insulin Treatment.

Type 1 diabetes mellitus (T1DM) is associated with impaired spermatogenesis and lower testosterone levels and epididymal weight. However, the underlying processes in the testis are unknown and remain to be elucidated. Therefore, the present study focused on the effects of T1DM on testicular function in a spontaneously diabetic rat model. BB/OKL rats after diabetes manifestation were divided into 3 groups: those without insulin treatment and insulin treatment for a duration of 2 and of 6 weeks. Anthropometrical data, circulating levels of gonadotrophins, testosterone, and inhibin B were measured. Intratesticular testosterone, oxidative stress, inflammation, and apoptosis were analyzed. Key enzymes of steroidogenesis were evaluated in the testis. Untreated diabetic rats had significantly lower serum follicle-stimulating hormone and luteinizing hormone levels. Serum and intratesticular testosterone levels significantly decreased in untreated diabetic rats compared to healthy controls. Key markers of Leydig cell function were significantly downregulated at the RNA level: insulin-like factor 3 (Insl3) by 53% (P = .006), Star by 51% (P = .004), Cyp11A1 by 80% (P = .003), 3Beta-Hsd2 by 61% (P = .005), and Pbr by 52% (P = .002). In the insulin-treated group, only Cyp11A1 and 3Beta-Hsd2 transcripts were significantly lower. Interestingly, the long-term insulin-treated group showed significant upregulation of most steroidogenic enzymes without affecting testosterone levels. Tumor necrosis factor α and apoptosis were significantly increased in the long-term insulin-treated rats. In conclusion T1DM, with a severe lack of insulin, has an adverse action on Leydig cell function. This is partially reversible with well-compensated blood glucose control. Long-term T1DM adversely affects Leydig cell function because of the process of inflammation and apoptosis.

Effect of prenatal DINCH plasticizer exposure on rat offspring testicular function and metabolism

In 2002, the plasticizer 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) was introduced in the European market as a substitute for endocrine-disrupting phthalates. We found that in utero exposure of rats to DINCH from gestational day 14 until parturition affected reproductive organ physiology and reduced circulating testosterone levels at post-natal day 60, indicating a long-term effect on Leydig cells of the testis. Metabolically, animals exhibited randomly increased serum glucose concentrations not associated with impaired glucose utilization. Analysis of liver markers in the serum showed a hepatic effect; e.g. reduced bilirubin levels and albumin/globulin ratio. At post-natal day 200, random appearance of testicular atrophy was noted in exposed offspring, and limited changes in other reproductive parameters were observed. In conclusion, DINCH exposure appears to directly affect Leydig cell function, likely causing premature aging of the testes and impaired liver metabolic capacity. These effects might be attenuated with physiologic aging.

Sirtuin 4 Regulates Lipopolysaccharide Mediated Leydig Cell Dysfunction.

Bacterial lipopolysaccharide (LPS) is the most important contributing factor in pathogenesis of bacterial infection in male accessory glands; and it has shown to inhibit testicular steroidogenesis and induce apoptosis. The present study demonstrates that LPS causes mitochondrial dysfunction via suppression of sirtuin 4 (SIRT4); which in turn affects Leydig cell function by modulating steroidogenesis and apoptosis. LC-540 Leydig cells treated with LPS (10 µg/ml) showed impaired steroidogenesis and increased cellular apoptosis. The mRNA and protein expression of SIRT4 were decreased in LPS treated cells when compared to controls. The obtained data suggest that the c-Jun N-terminal kinase (JNK) activation suppresses SIRT4 expression in LPS treated Leydig cells. Furthermore, the overexpression of SIRT4 prevented LPS induced impaired steroidogenesis and cellular apoptosis by improving mitochondrial function. These findings provide valuable information that SIRT4 regulates LPS mediated Leydig cell dysfunction.

Testosterone and body composition in men after treatment for rectal cancer.

Preoperative radiotherapy for rectal cancer may affect Leydig cell function. However, the diagnosis of posttreatment hypogonadism is complicated as sexual symptoms associated to hypogonadism can rely on adverse events of pelvic radiation and surgery. The objective of this study was to investigate the association of testosterone levels and body composition. The clinical value of such an association is tested subsequently in the study population. This was a longitudinal study with prospective registration during 2010-2012 and 1-year follow up. Men with rectal cancer stage I-III, treated with radiotherapy and surgery, were eligible, and 40 of 53 men were available for analysis. The areas of skeletal muscle and adipose tissue were assessed on a defined section of a computed tomography at baseline and after 1 year. Androgen levels were recorded from morning blood samples. The area of skeletal muscle was related to the level of bioavailable testosterone (P = 0.01) but not to the level of serum testosterone (P = 0.36). The subcutaneous adipose tissue was not related to testosterone levels. Men with posttreatment serum testosterone levels of 8-12 nmol/L and longitudinal loss of psoas muscle area had a significantly increased luteinizing hormone-testosterone ratio compared with those with longitudinal gain of psoas muscle. The area of psoas muscle is related to the unbound fraction of circulating testosterone in men treated for rectal cancer. The longitudinal loss of psoas muscle in men with borderline levels of serum testosterone seems to be an androgen-related symptom associated with compensatory activation of the pituitary-gonadal axis indicating a testicular failure in this group of patients.

Effects of bleomycin, etoposide and cisplatin treatment on Leydig cell structure and transcription of steroidogenic enzymes in rat testis

Cytotoxic anticancer chemotherapy affects pituitary–testicular hormonal axis in humans and in animals. This study investigated the effects on Leydig cells of three cycles of bleomycin, etoposide and cisplatin (0.75, 7.5, and 1.5mg/kg, respectively; BEP) chemotherapy in rat testis. The chemotherapy has induced hyperplasia of and degenerative changes in Leydig cells at the end of BEP exposure, which remained so even after a recovery time of 63 days. The increased testicular oxidative stress at the end of the chemotherapy returned to normal level after the recovery time. The chemotherapy has stimulated the transcription of scavenger receptor class type-B1 (SCARB1), steroidogenic acute-regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage (CYP11A1), CYP17A1, and inhibited that of 17β-hydroxysteroid dehydrogenase (HSD17B6) and CYP19A1 in association with increased cholesterol and decreased testosterone levels. Even after the recovery time, the chemotherapy still had inhibitory effects on the transcription of all of the above genes in addition to luteinizing hormone receptor and HSD3B1, but not on the StAR gene. The cholesterol and testosterone levels also did not show any significant differences with the control group. The decreased testosterone level at the end of chemotherapy was probably due to inhibition of HSD3B1 and HSD17B6 genes. In conclusion, clinically relevant dose-levels and treatment protocols of BEP chemotherapy adversely affect Leydig cell function. The BEP chemotherapy inhibits the transcription of steroidogenic enzymes and that these effects sustain over an extended period of time without returning to normal levels.

Sub-acute intravenous administration of silver nanoparticles in male mice alters Leydig cell function and testosterone levels

The aim of this study was to determine whether short-term, in vivo exposure to silver nanoparticles (AgNPs) could be toxic to male reproduction. Low dose (1mg/kg/dose) AgNPs were intravenously injected into male CD1 mice over 12 days. Treatment resulted in no changes in body and testis weights, sperm concentration and motility, fertility indices, or follicle-stimulating hormone and luteinizing hormone serum concentrations; however, serum and intratesticular testosterone concentrations were significantly increased 15 days after initial treatment. Histologic evaluation revealed significant changes in epithelium morphology, germ cell apoptosis, and Leydig cell size. Additionally, gene expression analysis revealed Cyp11a1 and Hsd3b1 mRNA significantly upregulated in treated animals. These data suggest that AgNPs do not impair spermatogonial stem cells in vivo since treatment did not result in significant decreases in testis weight and sperm concentrations. However, AgNPs appear to affect Leydig cell function, yielding increasing testicular and serum testosterone levels.

Age and season affect serum testosterone concentrations in cryptorchid stallions

Cryptorchidism, characterised by inguinal and/or abdominal retention of one or both testes, is the most common developmental defect encountered in equine veterinary practice. Most cases present with stallion-like behaviour in...

Expression of 11β‐Hydroxysteroid Dehydrogenase Type 1 and Glucocorticoid Receptors in Reproductive Tissue of Male Horses at Different Stages of Sexual Maturity

Glucocorticoids (GCs) as mediators of the stress response may affect Leydig cell function by inhibiting either luteinizing hormone receptor expression or testosterone biosynthesis. The isozymes 11β-hydroxysteroid dehydrogenase (11βHSD) 1 and 11βHSD2 control the intracellular cortisol levels. Little is known about the effects of stress on fertility in the equine. The objective of the present study was to determine the presence and cellular localization of glucocorticoid receptors (GCR) and glucocorticoid-metabolizing enzymes (11βHSD1 and 11βHSD2) in equine epididymal and testicular tissue with special regard to sexual maturation. Testicular and epididymal tissue was collected from 21 healthy stallions, and four age groups were designed: pre-pubertal, young, mature and older horses. Immunohistochemistry (IHC) analysis and quantitative real-time PCR (qRT-PCR) were used. Pre-pubertal horses showed higher testicular gene expression of 11βHSD1, 11βHSD2 and GCR than horses of all other groups (p < 0.05). A positive intranuclear immunoreaction for GCR was seen in epithelial cells of caput, corpus and cauda epididymidis and in Leydig cells. Significant differences (p < 0.05) between age groups occurred. The number of Leydig cells staining positive for GCR was highest in immature stallions (p < 0.05). The enzyme 11βHSD1 was localized in epithelial cells of the caput and corpus epididymidis and in Leydig cells. As determined by enzyme assay, nicotinamide adenine dinucleotide (NAD)-dependant dehydrogenase (oxidation) activity was not detected in testicular tissue from immature stallions but in all other age groups (n = 3 per group). Results of this study suggest a contribution of GCs to maturation of male reproductive tissue in horses. In mature stallions, expression of 11βHSD enzymes and the oxidative 11βHSD activity in Leydig cells and epididymal basal and principal cells suggest a protective role on these tissues contributing to physiological intracellular glucocorticoid concentrations.

Testosterone Production is Better Preserved After 16 than 20 Gray Irradiation Treatment Against Testicular Carcinoma In Situ Cells

To study the effect of 16 Gy radiotherapy (RT) vs. 20 Gy RT on Leydig cell function in men treated with radiotherapy against carcinoma in situ (CIS) of the testis. Fifty-one men who were treated between 1985 and 2005 were included. Fourteen men had been treated with 20 Gy and 37 with 16 Gy RT. Measurements of sex hormone-binding globulin and basic and stimulated testosterone, as well as luteinizing hormone levels were performed. The follow-up periods for the patients treated without additional chemotherapy were for the 20 Gy and 16 Gy group mean/median/min-max: 9.0/10.0/1.0-20.3 years and 4.0/3.1/0.4-14.1 years, respectively. During the follow-up period, men treated with 16 Gy RT had stable testosterone levels (-1.1%/year, p = 0.4), whereas men treated with 20 Gy had an annual decrease of 2.4% (p = 0.008). For the latter group, the testosterone decrease was most pronounced in the first 5 years, leveling off during the following 5 years. Additionally, more men treated with 20 Gy needed androgen substitution treatment. Our study showed an increased luteinizing hormone level for the men treated with 16 Gy, although this was not significant (p = 0.5). We anticipated a similar increase in the patients treated with 20 Gy but instead observed a decrease (-3.1%, p = 0.01). RT at 16 and 20 Gy seem to affect Leydig cell function differently, with 16 Gy RT better preserving testosterone levels and thus being preferred from an endocrinological point of view.

Adult varicocele

Adult varicocele presents a challenge for male reproductive specialists. We have yet to fully elucidate the pathophysiology of varicocele. The enigma of the varicocele, although a source of frustration for clinicians, has been a siren call for researchers as attested to by the substantial, if flawed body of literature on the topic. We critically review recent publications on varicocele. Although yielding mixed results, studies this year have explored the potential relationship between oxidative stress and varicocele-associated infertility. In clinically focused research, one group tackled the contentious question of efficacy of surgical varicocele management. Building on the errors of prior meta-analyses, this study takes a fresh view on an old but vital topic. Finally, it is becoming clearer that varicocele affects Leydig cell function as well as seminiferous tubular function, and is a risk factor for androgen deficiency. With exceptions, recent studies support a role for varicocelectomy in the management of infertile couples. In addition, evidence is accumulating that early repair of varicoceles, especially large varicoceles, may be effective in preventing future infertility and may be an effective treatment for androgen deficiency.

Varicocele is a risk factor for androgen deficiency

A growing body of evidence suggests that varicocele negatively affects Leydig cell function with a consequential decrease in testosterone production by the testes. We hypothesize that men with varicoceles have lower testosterone levels at every age than those without varicoceles.

Effect of a Dopamine Agoniston Luteinizing Hormone Receptors, Cyclic AMP Production and Steroidogenesis in Rat Leydig Cells

Dopamine agonists are known to increase the incidence of Leydig cell hyperplasia/adenomas when administered to rats over periods of 1–2 years. We have examined the early changes in factors affecting luteinizing hormone (LH)-controlled signal transduction pathways and steroidogenesis in Leydig cellsin vitroafter chronic oral administration of one of these dopamine agonists, Mesulergine (CU327-085) (N-(1–6,dimethylergolin-8a-yl)-N′,N′-dimethylsulphamide hydrochloride) to Sprague–Dawley (SD) rats. Eight-week-old rats were given this dopamine agonist (2 mg/kg body wt/day) in food for 1, 5, or 12 weeks. The Leydig cells from control and treated rats were purified by elutriation and density gradient centrifugation. The dopamine agonist treatment was found to decrease the specific binding of125I-human chorionic gonadotrophin (hCG) binding to the Leydig cells: a decrease was detected as early as 1 week after treatment and was more pronounced after 5 and 12 weeks. This was found to be due to a decrease in the LH/hCG receptor numbers and not to a decrease in LH/hCG-receptor binding affinity. Both basal and LH-stimulated cAMP and testosterone production were also decreased; cAMP production was decreased by approximately 50% by all concentrations of LH added whereas testosterone production was only decreased with submaximum stimulating concentrations of LH. The formation of testosterone in response to dibutyryl cAMP was also decreased by approximately 50%, indicating additional lesions in the signal transduction pathway. The addition of the cell permeant 22R-hydroxycholesterol (22R) demonstrated that testosterone but not pregnenolone production was decreased by treatment with the dopamine agonist, thus indicating that the 17α-hydroxylase/C17-20lyase may have been inhibited. Supporting evidence for this was found because the dopamine agonist also increased aromatase activity in the Leydig cells and thus the potential to produce estrogens; previous studies have shown that estradiol is an inhibitor of the 17-20 lyase enzyme. The addition of the dopamine agonist directly to the Leydig cells did not inhibit cAMP production or testosterone production except at high concentrations. It is concluded that treatment of rats with the dopamine agonist indirectly (i.e., via the pituitary) affects Leydig cell function resulting in a rapid decrease in LH receptors and cAMP and testosterone production. Aromatase activity is increased and thus the capacity to produce estrogens. These early changes in the signal transduction pathways and steroidogenesis may be involved in the Leydig cell hyperplasia/adenoma formation that subsequently occurs.

The Direct Effect of Hepatic Peroxisome Proliferators on Rat Leydig Cell Functionin Vitro

A review of the literature indicates that some compounds which produce hepatic peroxisome proliferation in rats also appear to produce Leydig cell adenomas, and some also affect the serum concentrations of testosterone and estradiol. Previous studies with the peroxisome proliferator ammonium perfluorooctanoate showed a direct effect on Leydig cells to alter steroidogenesis. It was therefore proposed that peroxisome proliferators in general may directly affect Leydig cell function to produce Leydig cell tumors by some undetermined mechanism. The present study investigated whether the following peroxisome proliferators directly affect Leydig cell functionin vitro:2,4-dichlorophenoxyacetic acid, ammonium perfluorooctanoate, acetylsalicylic acid, clofibric acid, ciprofibrate, gemfibrozil, tiadenol, tibric acid, trichloroacetic acid, trichloroethylene, and Wyeth 14,643. Leydig cells, isolated from adult Crl:CDBR rats (12–16 weeks old), were treated with peroxisome proliferator for 21 hr and the medium was assayed for estradiol. The function of the treated Leydig cell was evaluated by measuring the release of testosterone in response to human chorionic gonadotropin (hCG). In general, the peroxisome proliferators reduced the hCG-stimulated release of testosterone and either reduced or had no effect on the baseline release of testosterone. Of the 11 peroxisome proliferators, 8 increased the release of estradiol from Leydig cells treated for 1 day. Two more compounds were found to increase estradiol production when the treatment period was extended to 2 days. These effects were seen at noncytotoxic doses and at concentrations similar to those achieved in rat serum in dietary studies. The results suggest that peroxisome proliferators, as a class of compounds, directly modify the steroidogenic function of Leydig cellsin vitro.Some of these compounds are known to produce Leydig cell tumors in rats, but this association has yet to be established for other peroxisome proliferators. This suggests that compounds which directly affect Leydig cell functionin vitromay also induce Leydig cell tumorsin vivo.Further investigations are necessary to address the mechanism for thein vitroeffects on Leydig cells and to clarify the apparent relationship between peroxisome proliferator-induced changes in Leydig cell function and the development of Leydig cell tumors.

Expression of cytochrome P450 17alpha-hydroxylase/C17-20 lyase in the fetal rat testis is reduced by maternal exposure to exogenous estrogens.

Testosterone is required for normal development of the male reproductive tract. Synthesis of testosterone occurs in the Leydig cells and is dependent upon the expression of several enzymes, including cytochrome P450 17alpha-hydroxylase/C17-20-lyase (P450c17), which is highly regulated within the testis. The aim of the present study was to investigate whether maternal exposure to estrogenic chemicals was able to affect Leydig cell function in the developing male fetus at the time of masculinization. Pregnant rats were injected sc with diethylstilbestrol (DES; 100 or 500 micrograms/kg), 4-octylphenol (OP; 100 or 600 mg/kg), or vehicle (oil, control) on days 11.5 and 15.5 postcoitum. Doses were chosen to reflect the reported estrogenic potency of the chemicals in vitro. On day 17.5, fetal testes were fixed before performing in situ hybridization and immunocytochemistry, used for extraction of RNA, or homogenized in phosphate buffer for determination of 17alpha-hydroxylase enzyme activity. There was no difference between fetuses from control and treated mothers in either the overall histology of the testes or the apparent number of Leydig cells, as determined by immunocytochemistry with an antibody directed against 3beta-hydroxysteroid dehydrogenase. However, there was a consistent and striking reduction in the amount of P450c17 detected by immunocytochemistry in testes from the groups given the higher dose of DES or OP. These observations were supported by measurement of 17alpha-hydroxylase activity, which was significantly reduced compared with that in controls (6.25 +/- 0.65 pmol/testis x min) in fetuses from animals treated with 100 micrograms/kg DES (4.27 +/- 0.39; P < 0.05), 500 micrograms/kg DES (1.4 +/- 0.47; P < 0.001), or 600 micrograms/kg OP (4.25 +/- 0.33; P < 0.05). RT-PCR and in situ hybridization revealed that these changes were mirrored by reductions in P450c17 messenger RNA in testes from fetuses from treated mothers compared with control levels. In conclusion, maternal treatment with either a potent sythetic estrogen (DES) or a putative environmental estrogen (OP) results in reduced expression of the messenger RNA and protein for P450c17 in fetal Leydig cells. These results, therefore, provide a mechanism by which inappropriate exposure of the fetus to estrogenic chemicals might have an adverse effect on fetal steroid synthesis and masculinization.

Effect of testosterone on testicular steroidogenesis in the hypogonadal ( hpg) mouse

Previous studies have shown that androgens have direct inhibitory effects on steroidogenesis in active Leydig cells. It is not clear what effect androgens have on inactive Leydig cell either through direct action on the cell itself or indirectly through stimulation of Sertoli cell activity. The hpg mouse has undetectable levels of circulating gonadotrophins and the gonads fail to develop post-natally. The effect of androgen treatment on testicular steroidogenesis and morphology was examined in these animals. Treatment with testosterone propionate for two weeks significantly increased testicular and seminal vesicle weight. Seminiferous tubules showed marked development in androgen-treated animals, indicating increased Sertoli cell activity, but the abnormal Leydig cell morphology of the hpg testis was unchanged. Androgen production per testis in vitro was low in control hpg animals and remained unaffected by treatment with androgen. Similarly, the pattern of [ 3H]pregnenolone metabolism was not significantly affected by androgen treatment. The androgen content of the testis was higher in androgen-treated animals but this could be accounted for by uptake of administered steroid from the circulaton. It is concluded that androgens have no direct trophic effect on Leydig cells and that stimulation of Sertoli cell activity is not, in itself, sufficient to affect Leydig cell function.

Hormonal regulation of androgen biosynthesis by primary cultures of testis cells from neonatal rats.

Enzymatically dispersed testis cells derived from 7-day-old male rats maintained their gonadotropin-stimulated testosterone production for 18 days in culture. Treatment with hCG or LH stimulated androgen production in a dose-dependent manner, with ED50 values of 0.030 +/- 0.007 and 1.0 +/- 0.4 ng/ml for hCG and LH, respectively. Concomitant treatment with a phosphodiesterase inhibitor further enhanced LH action. In contrast, treatment with FSH, GH, or PRL was without effect. Treatment with forskolin, cholera toxin, or 8-bromo-cAMP induced dose-dependent increases in testosterone biosynthesis; this was accompanied by stimulation of 3 beta-hydroxysteroid dehydrogenase activity after treatment with hCG, forskolin, or 8-bromo-cAMP. RIA measurement of different androgens in HPLC-fractionated medium revealed that the main androgen secreted by the neonatal testis cells was testosterone, with lower production of 5 alpha-androstane-3 alpha,17 beta-diol and negligible 5 alpha-dihydrotestosterone, androstenedione, and androsterone. Treatment with epidermal growth factor, GnRH, and arginine vasopressin (AVP) decreased hCG-induced testosterone biosynthesis. Since the inhibitory actions of GnRH and AVP were blocked by concomitant addition of specific hormone antagonists, their inhibitory actions were probably mediated by specific testis receptors. In contrast, treatment with several potent synthetic steroid hormone analogs [diethylstilbestrol (an estrogen), dexamethasone (a glucocorticoid), R5020 (a progestin; 17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione), R1881 (an androgen; 17 beta-hydroxy-17 alpha-methyl-4,9,11-estratrien-3-one), or cyproterone acetate (an antiandrogen; 17 alpha-acetyloxy-6-chloro-1,2-dihydro-(1 beta,2 beta)3'-H-cyclopropa-(1,2) pregna-1,4,6-trien-3,20-dione)] did not affect testosterone biosynthesis in hCG-treated cells. These results demonstrate that testosterone production by neonatal testis cells is maintained by gonadotropins during prolonged culture; the ability of cAMP-generating drugs and a cAMP analog to mimic gonadotropin actions on testosterone biosynthesis and 3 beta-hydroxysteroid dehydrogenase activity suggests a mediatory role of cAMP in gonadotropin action; and AVP, epidermal growth factor, and GnRH, through their putative testis receptors, directly inhibit gonadotropin-stimulated testosterone synthesis, while various steroids (androgens, estrogens, progestins, and glucocorticoids) do not affect Leydig cell function in the neonatal testis. The present culture system offers a unique model for elucidating the hormonal control of Leydig cell androgen biosynthesis during neonatal development.

Post-weaning differential housing and testosterone secretion in male mice

The effect of different densities of animals per cage on basal testosterone secretion and its response to some stimuli was studied in prepuberal male mice. Mice housed with 110 or 55 cm2 of floor space per animal showed the same basal serum testosterone and hCG-induced testosterone release. Likewise, in a second experiment, the same basal serum testosterone and a similar response to acute noise stress were found in mice housed at 132, 66 or 22 cm2 of floor space per animal. These results suggest that post-weaning crowding did not affect Leydig cell function in male mice.

Specific Effect of Fluoroacetamide on Spermiogenesis1

To determine the effect of fluoroacetamide (FAA) on spermiogenesis 2 expermiments were conducted with adult male rats: 1) FAA was administered orally at dose levels ranging from 5-50 mg/kg of diet for 1 3 7 14 and 28 days; and 2) FAA was administered subcutaneously in doses ranging from 5-1000 mcg/1 ml saline daily for 4-56 days. After sacrifice the pituitary gland testes and adrenals were examined and compared with appropriate controls. In the first experiment FAA doses above 5 mg/kg diet caused a diminution of testes weight and this effect increased with the size of the FAA dose. Low doses of FAA (below 50 mg/kg diet or 250 mcg injected) inhibited the late stages of spermatid development while higher doses affected less mature germinal cells so that after several weeks of treatment only Sertoli cells and spermatogonia remained in the semniferous tubules. Prolonged administration of FAA at levels of 20 mg/kg diet or 250 mcg injected affected young spermatids and spermatocytes indicating a cumulative inhibitory effect. FAA does not appear to seriously affect Leydig cell function and low doses produce no general toxic effects. Further investigations into the mechanism of FAAs effect on spermiogenesis may lead to a method of blocking sperm production.