Sustained elevation of pulsatile growth hormone (GH) secretion and insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3), and IGFBP-5 concentrations during 30-day continuous subcutaneous infusion of GH-releasing peptide-2 in older men and women

This clinical study conducted by Bowers — one of the pioneering researchers of GH-releasing peptides — investigated the effects of continuous subcutaneous infusion of GHRP-2 over 30 days in healthy elderly men and women. The objective was to determine whether prolonged stimulation of the somatotropic axis by a GH secretagogue could reverse part of the age-related GH decline (somatopause).

The results demonstrated that continuous GHRP-2 infusion stimulated pulsatile GH secretion robustly, with a more than 3-fold increase on day 1 of treatment. Although there was some attenuation of the response over time, GH secretion remained elevated at 1.8-fold on days 14 and 30, demonstrating sustained efficacy without complete tachyphylaxis.

Concurrently, levels of IGF-I, IGFBP-3, and IGFBP-5 — biomarkers of the GH/IGF-1 axis with importance for bone and metabolic health — remained significantly elevated throughout the treatment period. The elevation of IGFBP-5 is particularly relevant, as this protein is associated with bone health and may potentiate the anabolic effects of IGF-I.

The safety profile was favorable, with no significant adverse effects, concerning glycemic changes, or cortisol elevation. The authors concluded that continuous GHRP-2 infusion represents a viable approach to partially reverse somatopause in the elderly, while maintaining the physiological pattern of pulsatile GH secretion.