Title: Effects of GHRP-2 and Hexarelin, Two Synthetic GH-Releasing Peptides, on GH, Prolactin, ACTH and Cortisol Levels in Man. Comparison with the Effects of GHRH, TRH and hCRH
Abstract: Arvat, E., L. Di Vito, B. Maccagno, F. Broglio, M. F. Boghen, R. Deghenghi, F. Camanni and E. Ghigo. Effects of Ghrp-2 and Hexarelin, two synthetic Gh-releasing peptides, on Gh, prolactin, Acth and cortisol levels in man. Comparison with the effects of Ghrh, Trh and hCrh. Peptides 18(6) 885–891, 1997.—GHRP-2 (d-Ala-d-βNal-Ala-Trp-d-Phe-Lys-NH2) and Hexarelin (HEX) (His-d-2-methylTrp-Ala-Trp-dPhe-Lys-NH2) are synthetic, non-natural super-analogs of GHRP-6 endowed with potent stimulatory effect on GH secretion and slight stimulatory effect on PRL, ACTH and cortisol levels. Their GH-releasing activity has never been compared each other and their effects on PRL, ACTH and cortisol have never been compared with that of other stimuli. To clarify these points, in 6 normal young adults (22–27 yr) we studied the GH, PRL, ACTH and cortisol responses to 1 and 2 μg/kg IV GHRP-2 and HEX comparing them with that after 1 μg/kg IV GHRH and 400 μg IV TRH + 2 μg/kg IV hCRH. The GH responses to 2 μg/kg IV GHRP-2 or HEX, compared with those to 1 μg/kg GHRH, were also studied in 6 normal elderly subjects (66–73 yr). In young adults 1 μg/kg IV GHRP-2 and HEX induced a similar, strong GH response, which was higher (p < 0.05) than that to GHRH. The administration of 2.0 μg/kg IV GHRP-2 and HEX again elicited a similar GH response, which was higher (p < 0.05) than that after the 1.0 μg/kg dose. In elderly subjects, the GH responses to 2.0 μg/kg IV GHRP-2 and HEX were similar and higher than that to GHRH (p < 0.05) but lower (p < 0.01) than those in young subjects. In young adults, the PRL responses to all doses of GHRP-2 or HEX were similar and lower (p < 0.01) than that to TRH. On the other hand, all doses of GHRP-2 and HEX stimulated to the same extent both ACTH and cortisol. These responses were similar to those to hCRH. In conclusion, our results demonstrate that, in man, GHRP-2 and HEX have similar, dose- and age-dependent stimulatory effect on somatotrope secretion, releasing more GH than GHRH. The activity of both GHRP-2 and HEX is not fully specific, as they induce similar increases in PRL, ACTH and cortisol levels. The PRL-releasing activity of GHRPs is lower than that of TRH while their ACTH/cortisol-releasing activity is similar to that of hCRH.
Publication Year: 1997
Publication Date: 1997-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 83
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