Send to

Choose Destination
Peptides. 1997;18(6):885-91.

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.

Author information

Department of Internal Medicine, University of Turin, Italy.


GHRP-2 (D-Ala-D-beta Nal-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 ahs 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 micrograms/kg i.v. GHRP-2 and HEX comparing them with that after 1 micrograms/kg i.v. GHRH and 400 micrograms i.v. TRH + 2 micrograms/kg i.v. hCRH. The Gh responses to 2 micrograms/kg i.v. GHRP-2 or HEX, compared with those to 1 microgram/kg GHRH, were also studied in 6 normal elderly subjects (66-73 yr). In young adults 1 microgram/kg i.v. 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 micrograms/kg i.v. GHRP-2 and HEX again elicited a similar GH response, which was higher (p < 0.05) than that after the 1.0 microgram/kg dose. In elderly subjects, the GH 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) responses were similar to those to hCRH. In conclusion, our results demonstrate that, in man, GHRP-2 and HEX have similar, 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.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center