Hyperglycemic action of synthetic C-terminal fragments of human growth hormone.
Ng. F M FM; Bornstein. J J
Key Findings
- Peptides 172‑191, 176‑191, 177‑191, and 178‑191 raise blood glucose and insulin in rats.
- Peptides 179‑191 and 180‑191 have no effect on glucose or insulin.
- A single dose of the 178‑191 fragment reduces insulin sensitivity, indicating a potential metabolic downside.
Practical Outcomes
- These results suggest that using hGH‑fragment‑176‑191 may worsen blood sugar control and insulin sensitivity, so it could be risky for those focused on metabolic health or longevity. Until human data are available, it’s prudent to avoid this fragment for fat‑loss or performance purposes.
Summary
In rats, short pieces of human growth hormone that include the 176‑191 region cause a quick spike in blood sugar and a longer increase in insulin, and they make the animals less sensitive to insulin. Two nearby fragments (179‑191 and 180‑191) did nothing. The effect only shows up when the peptide has the right sequence and shape.
Abstract
The synthetic peptides corresponding to amino acids 172-191, 176-191, 177-191, 178-191, 179-191, and 180-191 of human growth hormone (hGH) have been studied for their in vivo effects in normal rats. Four of the peptides (hGH 172-191, 176-191, 177-191, and 178-191) produced a short-lived rise in blood glucose and a more sustained rise in plasma insulin, whereas the other two (hGH 179-191 and 180-191) were inert in the systems tested. A single dose (5 nmol/kg body wt) of the peptides containing the amino acids sequence 178-191 of the hGH molecule significantly reduced insulin sensitivity of the animals in intravenous insulin tolerance tests. The findings also indicate that the biologically active peptides must not only have the minimum of the informational sequence but also that this must be in correct physical configuration.
Study Information
pubmed
1978
10.1152/ajpendo.1978.234.5.e521