Arginine and growth hormone-releasing hormone restore the blunted growth hormone-releasing activity of hexarelin in elderly subjects

E Arvat, L Gianotti, S Grottoli, B P Imbimbo, V Lenaerts, R Deghenghi, F Camanni, E Ghigo
1994 Journal of Clinical Endocrinology and Metabolism  
Although both spontaneous and stimulated GH secretion undergo an age-related decline, the secretory capacity of somatotrope cells is preserved in human aging. In the present study we compared the GH responses to hexarelin, GHRH, and the combined administration of hexarelin and GHRH or arginine in young and elderly subjects. Thirteen young (24-to 30-yr-old) and 16 elderly (65-to 84-yr-old) normal males were divided into 2 groups. The first group (7 young and 8 elderly subjects) received the
more » ... ) received the following as single iv injections during 3 different treatment sessions: hexarelin (2 pg/kg), GHRH (2 rg/kg), or hexarelin (2 rg/kg) plus GHRH (2 Kg/kg). The second group (6 young and 8 elderly subjects) was administered single iv injections of hexarelin (2 rg/kg) or hexarelin (2 rg/kg) plus arginine (0.5 g/kg) during 2 different treatment sessions. In both groups basal IGF-I levels in the elderly were lower than those in young subjects (114.5 f 18.7 vs. 211.5 + 19.1 pg/L; P < 0.001). In the first group the GH response to hexarelin was greater in young compared to elderly subjects (area under the curve from O-120 = 4849 + 601 vs. 2112 f 683 pg.min/L; P < 0.001). GHRH elicited a lower GH response than that induced by hexarelin in both young (1455 + 102 pg/h. L; P < 0.02) and elderly subjects (563 f 87
doi:10.1210/jcem.79.5.7962341 pmid:7962341 fatcat:nponzqv4wjcybnlvggpe3duzma