Dataset Information

Age in men does not determine gonadotropin-releasing hormone's dose-dependent stimulation of luteinizing hormone secretion under an exogenous testosterone clamp.

ABSTRACT:

Background

Aging is associated with a decline in incremental LH pulse amplitude, which could be due to decreased GnRH secretion or impaired GnRH action.

Hypothesis

Inconsistent published studies of GnRH action in older men may be due to disparate sex-steroid milieus.

Facility

This study was conducted at a clinical translational-research unit.

Subjects

We studied 16 healthy men (8 young men and 8 older men).

Methods

An overnight transdermal testosterone (T) clamp was implemented before randomly ordered injections of 0, 2.5, 10, 25, 250, and 750 ng GnRH on separate days (96 study sessions).

Outcomes

LH responses were quantified by variable-waveform deconvolution analysis.

Results

The T clamp maintained age-invariant mean concentrations of total, bioavailable, and free T, SHBG, LH, FSH, and prolactin. By two-way analysis of covariance, GnRH dose (P < 0.001) but not age (0.15 < or = P < or = 0.83) determined mean, peak, incremental, and pulsatile LH responses. Statistical power (median) was 95, 98, 90, and 99% to detect a 30% or greater age contrast at P < or = 0.05 in mean, peak, incremental, and pulsatile LH responses, and greater than 99% to detect a 30% or greater age contrast in bioavailable or total T concentrations. Higher GnRH doses (P < 0.001) abbreviated LH secretory bursts in both age groups.

Conclusion

In the face of eugonadal concentrations of total, bioavailable, and free T, young and older men exhibit remarkably similar LH responses to a 300-fold dose range of exogenous GnRH. Accordingly, previously reported disparate effects of age on GnRH action may reflect in part age-discrepant sex-steroid milieus.

SUBMITTER: Iranmanesh A

PROVIDER: S-EPMC2902075 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Age in men does not determine gonadotropin-releasing hormone's dose-dependent stimulation of luteinizing hormone secretion under an exogenous testosterone clamp.

Iranmanesh Ali A Mulligan Thomas T Veldhuis Johannes D JD

The Journal of clinical endocrinology and metabolism 20100331 6

<h4>Background</h4>Aging is associated with a decline in incremental LH pulse amplitude, which could be due to decreased GnRH secretion or impaired GnRH action.<h4>Hypothesis</h4>Inconsistent published studies of GnRH action in older men may be due to disparate sex-steroid milieus.<h4>Facility</h4>This study was conducted at a clinical translational-research unit.<h4>Subjects</h4>We studied 16 healthy men (8 young men and 8 older men).<h4>Methods</h4>An overnight transdermal testosterone (T) cla ...[more]

PMID: 20357176

Similar Datasets

Project description:BackgroundLuteinizing hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing hormone and by alterations in gonadotropin releasing hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Galpha proteins with effectors such as phospholipase Cbeta. Previously, we reported that gonadotropin releasing hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing hormone-induced luteinizing hormone secretion from cultured rat pituitary cells.ResultsA truncated version of RGS3 (RGS3T = RGS3 314-519) inhibited gonadotropin releasing hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more 35S-Gqalpha than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing hormone-stimulated luteinizing hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing hormone stimulated 3H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqalpha protein.ConclusionsRGS3 inhibits gonadotropin releasing hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqalpha protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing hormone-stimulated inositol trisphosphate production.

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.

Dataset Information

Age in men does not determine gonadotropin-releasing hormone's dose-dependent stimulation of luteinizing hormone secretion under an exogenous testosterone clamp.

Background

Hypothesis

Facility

Subjects

Methods

Outcomes

Results

Conclusion

Publications

Age in men does not determine gonadotropin-releasing hormone's dose-dependent stimulation of luteinizing hormone secretion under an exogenous testosterone clamp.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets