Novel relationships of age, visceral adiposity, insulin-like growth factor (IGF)-I and IGF binding protein concentrations to growth hormone (GH) releasing-hormone and GH releasing-peptide efficacies in men during experimental hypogonadal clamp.

ABSTRACT:

Background

Sex steroids influence GH secretion in complex ways.

Hypothesis

Analyses in a low sex-steroid milieu will help unveil the effects of age and other nonsteroidal regulators on GH secretion.

Context

The study was conducted in a tertiary medical center.

Subjects

The study group included 13 healthy young men and 12 healthy older men.

Methods

We used GnRH agonist-induced down-regulation of testosterone and estradiol secretion, followed by consecutive infusion of l-arginine and GHRH or GHRP-2, to test secretagogue efficacies.

Outcomes

We measured basal and pulsatile GH secretion.

Results

During experimental testosterone/estradiol deprivation, older (57 +/- 1.7 yr) men maintained: 1) 6.8-fold less pulsatile GH secretion (P < 0.001); and

SUBMITTER: Veldhuis JD 

PROVIDER: S-EPMC2690428 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature