Gender, sex-steroid, and secretagogue-selective recovery from growth hormone-induced feedback in older women and men.
This study found that gender and sex-steroid supplementation significantly affect growth hormone recovery from autoinhibition, with distinct effects based on the type of secretagogue used.
Where it sits
this study against the rest of the ghrp-2 (pralmorelin) corpusSummary and findings
This study measured the effects of gender, sex-steroid supplementation, and secretagogue type on growth hormone (GH) recovery from autoinhibition in 10 healthy postmenopausal women and 10 comparably aged men. Participants underwent a double-blind, crossover treatment with either testosterone or estradiol versus placebo, following an intravenous pulse of GH. The findings indicated that both nadir and peak GH levels were significantly influenced by the type of peptide administered.
Abstract
<h4>Context</h4>GH negatively regulates its own secretion. How gender, sex steroids, and secretagogues modulate GH autofeedback is not known.<h4>Hypothesis/objective</h4>Supplementation with sex steroids and/or a peptidyl secretagogue will enhance the escape of GH from autoinhibition, thus framing a mechanism for amplifying pulsatile GH secretion.<h4>Subjects and setting</h4>Ten healthy postmenopausal women and 10 comparably aged men participated at the Clinical-Translational Science Unit.<h4>Design/interventions</h4>Randomly ordered, double-blind, prospective crossover treatment with placebo vs. testosterone (men) or placebo vs. estradiol (women). Autofeedback was imposed by an iv pulse of GH. Recovery of feedback inhibition was quantified during constant infusion of saline, GHRH, or GH-releasing peptide-2 (three peptide categories).<h4>Outcomes/results</h4>During negative feedback, total (integrated) GH recovery depended upon gender (P = 0.017), sex hormone (P < 0.001), and peptide category (P < 0.001). Mechanistic analysis revealed that feedback-suppressed nadir GH concentrations were determined by sex-steroid treatment (P = 0.018) but not by gender (P = 0.444). Peak GH escape was controlled by both treatment (P = 0.004) and gender (P = 0.003). Nadir GH and peak GH during feedback were enhanced by GHRH or GHRP-2 (P < 0.001 for both). Gender × peptide (P = 0.012 for nadir GH), treatment × peptide (P < 0.001 total and peak GH), and gender × treatment (P = 0.017 nadir GH) regulated GH recovery interactively.<h4>Conclusion</h4>Gender, sex-steroid supplementation, and secretagogue type confer distinct feedback-rescuing effects, introducing a new level of complexity in the control of pulsatile GH regulation.
Background
Not reported in abstract.
Methods
Not reported in abstract.
Results
Not reported in abstract.
Interpretation
Not reported in abstract.
Limitations
Not reported in abstract.