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Correlation of protein kinase activation and testosterone production after stimulation of Leydig cells with luteinizing hormone.

ABSTRACT: The effect of different doses of luteinizing hormone on activation of protein kinases, cyclic AMP and testosterone production was studied in purified rat testis Leydig-cell preparations in the presence of 3-isobutyl-1-methylxanthine (a phosphodiesterase inhibitor). In addition, the nature of the protein kinases present in these cells and other tissues was investigated. The following results were obtained. 1. With all the amounts of luteinizing hormone used (0.1-1000 ng/ml), both activation of protein kinase and stimulation of testosterone production were demonstrated. With the lowest amount of luteinizing hormone (0.1 ng/ml), an 8.4+/-0.9% (S.E.M.,n=6) stimulation of protein kinase activation occurred, increasing to 100% with 1000 ng/ml, compared with 3.2+/-1.0%(S.E.M.,n=7) and 100% stimulation of testosterone production with 0.1 and 100 ng/ml respectively. 2. With amounts of luteinizing hormone up to 1 ng/ml (which gave half-maximal stimulation of testosterone production) no detectable increases in net cyclic AMP production were obtained. With higher amounts of luteinizing hormone, cyclic AMP production increased, but maximal production was not reached with 1000 ng/ml. 3. Two isoenzymic forms of protein kinase were present in Leydig cells and seminiferous tubules; type I was eluted with 0.075 M-and type II with 0.22-0.25 m-NaCl from DEAE-cellulose columns. 4. The protein kinase activity was not affected by the presence of erythrocytes in the Leydig-cell preparation, but varied depending on the type of histone used as substrate (histone F2b greater than mixed greater than histone F1).

SUBMITTER: Cooke BA

PROVIDER: S-EPMC1164259 | biostudies-other | 1976 Dec

REPOSITORIES: biostudies-other

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Project description:BACKGROUND: Leydig cells are the primary source of testosterone in male vertebrates. The biosynthesis of testosterone in Leydig cells is strictly dependent on luteinizing hormone (LH). On the other hand, it can be directly inhibited by excessive glucocorticoid (Corticosterone, CORT, in rats) which is beyond the protective capability of 11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) and type 2 (11beta-HSD2; encoded by gene Hsd11b2 in rats) in Leydig cells. Our previous study found that LH increases 11beta-HSD1 expression in rat Leydig cells, but the effect of LH on the expression and activity of 11beta-HSD2 is not investigated yet. METHODS: The Leydig cells were isolated from male Sprague-Dawley rats (90 days of age). After Leydig cells were incubated either for 24 h with various concentrations of LH (2.5, 5, 10 and 20 ng/mL) or for different time periods (2, 8, 12 and 24 h) with 20 ng/mL LH, the mRNA expression of 11beta-HSD2 was measured by real-time PCR. 11beta-HSD2 protein levels in Leydig cells were assayed by Western Blot and 11beta-HSD2 enzyme activity was determined by calculating the ratio of conversion of [3H]CORT to [3H]11-dehydrocorticosterone by 24 h after stimulation with 20 ng/ml LH. Four reporter gene plasmids containing various lengths of Hsd11b2 promoter region were constructed and transfected into mouse Leydig tumor cells to investigate the effect of LH on Hsd11b2 transcription. A glucocorticoid-responsive reporter gene plasmid, GRE-Luc, was constructed. To evaluate influence of LH on intracellular glucocorticoid level, rat Leydig cells were transfected with GRE-Luc, and luciferase activities were measured after incubation with CORT alone or CORT plus LH. RESULTS: We observed dose- and temporal-dependent induction of rat 11beta-HSD2 mRNA expression in Leydig cells subject to LH stimulation. The protein and enzyme activity of 11beta-HSD2 and the luciferase activity of reporter gene driven by promoter regions of Hsd11b2 were increased by LH treatment. LH decreased the glucocorticoid-induced luciferase activity of GRE-Luc reporter gene. CONCLUSION: The results of the present study suggest that LH increases the expression and enzyme activity of 11beta-HSD2, and therefore enhances capacity for oxidative inactivation of glucocorticoid in rat Leydig cells in vitro.

Project description:INTRODUCTION:Hypersexual disorder as suggested to be included in the Diagnostic and Statistical Manual of Mental Disorders-5 integrates aspects of sexual desire deregulation, impulsivity, and compulsivity. However, it is unknown how it affects gonadal activity and the function of the hypothalamus-pituitary-gonadal (HPG) axis. AIM:The aim of this study was to investigate testosterone and luteinizing hormone (LH) levels in hypersexual men compared with healthy controls. Furthermore, we investigated associations between epigenetic markers and hormone levels. METHODS:Basal morning plasma levels of testosterone, LH, and sex hormone-binding globulin (SHBG) were assessed in 67 hypersexual men (mean age: 39.2 years) compared with 39 age-matched healthy controls (mean age: 37.5 years). The Sexual Compulsivity Scale and the Hypersexual Disorder: Current Assessment Scale were used for assessing hypersexual behavior, the Montgomery-Åsberg Depression Scale-self rating was used for depression severity, and the Childhood Trauma Questionnaire (CTQ) was used for assessing history of childhood adversity. The genome-wide methylation pattern of more than 850 K CpG sites was measured in whole blood using the Illumina Infinium Methylation EPIC BeadChip. CpG sites located within 2,000 bp of the transcriptional start site of hypothalamus pituitary adrenal (HPA) and HPG axis-coupled genes were included. MAIN OUTCOME MEASURES:Testosterone and LH plasma levels in association with clinical rating and a secondary outcome was the epigenetic profile of HPA and HPG axis-coupled CpG sites with testosterone and LH levels. RESULTS:LH plasma levels were significantly higher in patients with hypersexual disorder than in healthy volunteers. No significant differences in plasma testosterone, follicle stimulating hormone, prolactin, and SHBG levels were found between the groups. There were no significant associations between DNA methylation of HPA and HPG axis-coupled genes and plasma testosterone or LH levels after multiple testing corrections. CONCLUSIONS:Subtle dysregulation of the HPG axis, with increased LH plasma levels but no difference in testosterone levels may be present in hypersexual men. Chatzittofis A, Boström AE, Öberg KG, et al. Normal Testosterone but Higher Luteinizing Hormone Plasma Levels in Men With Hypersexual Disorder. Sex Med 2020;8:243-250.

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Correlation of protein kinase activation and testosterone production after stimulation of Leydig cells with luteinizing hormone.

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