GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Estradiol Replacement Improves High-Fat Diet-Induced Obesity by Suppressing the Action of Ghrelin in Ovariectomized Rats.
Yokota-Nakagi. Naoko N; Takahashi. Haruka H; Kawakami. Mizuho M; Takamata. Akira A; Uchida. Yuki Y; Morimoto. Keiko K
Key Findings
- Estradiol replacement reduced high‑fat diet intake and weight gain in ovariectomized rats.
- GHRP‑6 increased food intake and activated appetite neurons only in rats without estradiol.
- Estradiol lowered gastric ghrelin and GHSR protein levels, while plasma acyl ghrelin stayed the same.
Practical Outcomes
- For biohackers using GHRP‑6, estrogen status may influence how strong its appetite‑stimulating effect is. Women on estrogen therapy (or those with higher estrogen levels) might experience a blunted hunger response to GHRP‑6. However, the data come from a specific rat model, so direct human dosing recommendations are not supported.
Summary
In female rats without ovaries, giving estradiol (a form of estrogen) made them eat less and gain less weight on a high‑fat diet, and it blocked the appetite‑boosting effect of the peptide GHRP‑6. The hormone lowered the amount of ghrelin and its receptor in the stomach, but didn’t change the level of ghrelin circulating in the blood.
Abstract
This study aims to investigate the effects of estradiol replacement on the orexigenic action of ghrelin in ovariectomized (OVX) obese rats fed with a high-fat diet (HFD). Four weeks after OVX at 9 weeks of age, Wistar rats were subcutaneously implanted with either 17β-estradiol (E2) or placebo (Pla) pellets and started on HFD feeding. After 4 weeks, growth hormone-releasing peptide (GHRP)-6, a growth hormone secretagogue receptor (GHSR) agonist injected intraperitoneally, induced changes in HFD intake, and c-Fos-positive neurons in the hypothalamic arcuate nucleus (ARC) were measured in both groups. The ghrelin protein and mRNA levels, as well as GHSR protein in stomach, were analyzed by Western blotting and real-time PCR. HFD increased energy intake and body weight in the Pla group, while it temporarily reduced these in the E2 group. GHRP-6 enhanced HFD intake and activated neurons in the ARC only in the Pla group. Furthermore, gastric ghrelin and GHSR protein levels were lower in the E2 group than in the Pla group, but plasma acyl ghrelin levels were similar in both groups. Our results suggest that E2 replacement improves obesity by inhibiting the orexigenic action of ghrelin via downregulation of ghrelin and its receptor in stomach in HFD-fed OVX rats.
Study Information
pubmed
2020
2020-03-26T00:00:00.000Z
10.3390/nu12040907
14
51