Melatonin influences insulin secretion primarily via MT(1) receptors in rat insulinoma cells (INS-1) and mouse pancreatic islets.
Level 5 - mechanism / opinion, no new human data
In vitro cell line and ex vivo animal tissue experiment with no human data
PubMed 22288848 · doi:10.1111/j.1600-079X.2012.00959.x
What was done
Researchers evaluated the specific role of the MT1 melatonin receptor in regulating insulin secretion using RNA interference knockdown in rat insulinoma cells (INS-1) and isolated pancreatic islets from wild-type, MT1-knockout, and MT1/MT2 double-knockout mice. Insulin secretion was measured via radioimmunoassay, intracellular cAMP via ELISA, gene expression via real-time RT-PCR, and CREB phosphorylation via immunocytochemistry following melatonin treatments and secretagogue stimulation.
What was found
The abstract reports directional findings without numerical values. In INS-1 cells, MT1 knockdown significantly increased rIns1 mRNA expression and basal insulin secretion. Melatonin inhibited glucagon-stimulated insulin release and decreased glucagon-like peptide 1-induced effects in control INS-1 cells, but failed to reduce insulin secretion, lower IBMX-stimulated cAMP, or alter CREB phosphorylation in MT1-knockdown cells. In ex vivo mouse islets, melatonin reduced insulin release in wild-type islets, but had no significant effect in islets from MT1-knockout or MT1/MT2 double-knockout mice.
Why it matters
The findings demonstrate that melatonin suppresses beta-cell insulin secretion and downstream cAMP signaling primarily through the MT1 receptor isoform.
Limits
The study is restricted to in vitro rat cell lines and ex vivo mouse islets, lacking in vivo physiological data and human islet confirmation. Specific sample sizes, replicate counts, effect sizes, and exact p-values were not reported in the abstract.
Cited by
- supports Melatonin inhibits insulin production in pancreatic beta cells.