GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Influence of chronic treatment with the growth hormone secretagogue Ipamorelin, in young female rats: somatotroph response in vitro.
Jiménez-Reina. L L; Cañete. R R; de la Torre. M J MJ; Bernal. G G
Key Findings
- Chronic Ipamorelin increased the density of hormone‑release granules in pituitary cells without changing cell numbers
- Acute (4‑hour) exposure to Ipamorelin, GHRP‑6, or GHRH raised the percentage of somatotroph cells in culture
- Baseline intracellular GH was lower after chronic Ipamorelin, but only the Ipamorelin‑treated group could raise GH levels again with a short‑term dose
- The study suggests Ipamorelin can dynamically modulate pituitary GH storage and release in young female rats
Practical Outcomes
- For biohackers, this hints that long‑term Ipamorelin might prime the pituitary to react more sharply to short bursts of the peptide, potentially enhancing GH spikes. However, baseline GH stores may be reduced, and the results are from rats, so human effects and optimal dosing remain uncertain.
Summary
In young female rats, giving Ipamorelin for three weeks changed how pituitary cells store and release growth hormone. The cells didn’t increase in number, but they packed more hormone‑release granules and responded more strongly when given a short‑term dose of Ipamorelin or similar compounds. Baseline hormone levels inside the cells were actually lower after chronic treatment, but they could be boosted again with a quick dose.
Abstract
Growth hormone (GH) is secreted in the anterior pituitary gland by the somatotroph cells. Secretion is regulated by growth hormone releasing hormone (GHRH) and somatostatin. Morever, GH secretagogues (GHS) can exert a considerable effect on GH secretion. In order to determine the effects of chronic treatment with the GHS Ipamorelin on the composition of the somatotroph cell population and on somatotroph GH content, an in vitro analysis was performed of the percentage of somatotroph cells (% of total), the ratio of different GH cell types (strongly/weakly-staining) and individual GH content, in pituitary cell cultures obtained from young female rats receiving Ipamorelin over 21 days (Ipamorelin group) and the effects were compared with those of GHRH (GHRH group) or saline (saline group). The ultrastructure of somatotroph cells did not change, but the volume density of secretion granules was increased (P<0.05) by previous in vivo Ipamorelin or GHRH treatment. In 3-day basal pituitary cell monolayer cultures, the percentage of somatotroph cells showed no modifications between groups, nor was there any change in the ratio of strongly/weakly immunostaining GH cells. In the Ipamorelin group alone, in vitro treatment with Ipamorelin (10(-8) M), or GHRP 6 (10(-8) M), or GHRH (10(-8) M) for 4 hours, increased the percentage of somatotroph cells, without modifying the ratio of strongly/weakly immunostained GH cells. Basal intracellular GH content in somatotroph cells over 4 hours was lower in the Ipamorelin group and the GHRH group than in the saline group. Only in the Ipamorelin group did Ipamorelin (10(-8) M), GHRP 6 (10(-8) M) and GHRH (10(-8) M) prompt increased intracellular GH content. These data suggest that, at least in the young female rat, the GHS Ipamorelin is able to exert a dynamic control effect on the somatotroph population and on GH hormone content.
Study Information
pubmed
2002
10.14670/hh-17.707