Mechanism of ipamorelin-evoked insulin release from the pancreas of normal and diabetic rats.
Adeghate. Ernest E; Ponery. Abdul Samad AS
Key Findings
- Ipamorelin significantly increased insulin secretion from pancreatic tissue of both normal and diabetic rats.
- The insulin‑releasing effect was reduced by diltiazem (a calcium channel blocker) and by adrenergic blockers like yohimbine, propranolol, and a mix of atropine, propranolol, and yohimbine.
- Atropine specifically lowered ipamorelin‑induced insulin release in diabetic rats but not in normal rats, indicating a role of cholinergic pathways in diabetes.
Practical Outcomes
- If you’re using ipamorelin for its growth‑hormone benefits, be aware it may also raise insulin levels, which could affect blood‑sugar control. Until human data are available, avoid assuming it will improve glucose metabolism and monitor glucose if you combine it with other metabolic interventions.
Summary
In rats, the peptide ipamorelin not only boosts growth hormone but also triggers the pancreas to release more insulin, even in diabetic animals. This insulin‑boosting effect can be blocked by drugs that interfere with calcium channels or certain nerve‑signal receptors, showing how ipamorelin works through those pathways. The findings come from lab‑based rat tissue experiments, not human trials.
Abstract
To examine the effect of ipamorelin (IPA), a novel pentapeptide with a strong growth hormone releasing potency, on insulin secretion from pancreatic tissue fragments of normal and diabetic rats. Diabetes mellitus was induced by streptozotocin (60 mg kg(-1)). Four weeks after the induction of diabetes, pancreatic tissue fragments of normal and diabetic rats were removed and incubated with different concentrations (10(-12) - 10(-6) M) of IPA. Insulin release from the pancreas was measured by radioimmunoassay. Ipamorelin evoked significant (p<0.04) increases in insulin secretion from the pancreas of normal and diabetic rats. Either diltiazem or yohimbine or propranolol or a combination of atropine, propranolol and yohimbine inhibited IPA-evoked insulin secretion significantly (p<0.03) from the pancreas of normal and diabetic rats. Atropine caused a significant (p<0.007) reduction in the IPA-induced insulin secretion in diabetic but not in normal rats. IPA stimulates insulin release through the calcium channel and the adrenergic receptor pathways. This is the first study to examine the effect of ipamorelin on insulin secretion in the pancreas.
Study Information
pubmed
2004