GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Arginine enhances the growth hormone-releasing activity of a synthetic hexapeptide (GHRP-6) in elderly but not in young subjects after oral administration.
Ghigo. E E; Arvat. E E; Rizzi. G G; Bellone. J J; Nicolosi. M M; Boffano. G M GM; Mucci. M M; Boghen. M F MF; Camanni. F F
Key Findings
- Elderly participants had lower IGFâI levels and a weaker GH response to GHRH compared with young participants.
- Oral GHRPâ6 (300âŻÂ”g/kg) raised GH in both age groups, but the rise was smaller in the elderly.
- Adding 8âŻg of oral arginine to GHRPâ6 more than doubled the GH peak in elderly subjects (22.1âŻÂ”g/L) and made it higher than any stimulus tested in young adults.
- Arginine did not enhance the GH response to GHRPâ6 in the young group.
Practical Outcomes
- For older individuals seeking to boost GH, a protocol of oral GHRPâ6 (â300âŻÂ”g/kg) combined with 8âŻg of arginine appears more effective than GHRPâ6 alone. Younger users are unlikely to gain extra benefit from arginine. Because the study involved only eight participants per group, start with modest doses, monitor hormone responses, and consider the limited data before adopting the regimen.
Summary
Taking 8âŻg of arginine together with an oral dose of GHRPâ6 dramatically increased growth hormone release in older adults, while it had no extra effect in younger people.
Abstract
In man the GH-releasing hexapeptide His-DTrp-Ala-Trp-DPhe-Lys-NH2 (GHRP-6) has been shown to be active even after oral administration. On the other hand, it has been shown that arginine (ARG) totally restores the reduced somatotropic responsiveness to GHRH observed in aging. Based on the foregoing, in this study we verified the GH-releasing activity of oral GHRP-6 (300 micrograms/kg) in normal aging and the possible enhancing effect of 8 g oral ARG on the GH-releasing effect of GHRP-6. Eight young (age 24-32 yr) and 8 elderly (age 66-85 yr) subjects were studied. In all the GH response to GHRH (1 microgram/kg iv) was also studied. Both IGF-I levels and the GH response to iv GHRH were lower in elderly than in young subjects (mean +/- SE, IGF-I: 65.1 +/- 9.1 vs 142.9 +/- 9.4 micrograms/L, p < 0.0001; GH peak: 5.4 +/- 1.0 vs 13.6 +/- 0.8 micrograms/L, p < 0.0001). Oral GHRP-6 administration induced a GH rise in elderly which was lower, though not significantly, than that in young subjects (GH peak: 9.9 +/- 2.0 vs 16.2 +/- 5.4 micrograms/L). Oral ARG administration enhanced the GHRP-6-induced GH rise in elderly (GH peak: 22.1 +/- 3.3 micrograms/L, p < 0.01 vs GHRP-6 alone) while failed to modify it in young subjects (GH peak: 13.5 +/- 3.4 micrograms/L). The GH response to oral ARG+GHRP-6 in elderly was higher than that to all stimuli in young adults (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Study Information
pubmed
1994
10.1007/bf03347707