Yes, vasoactive intestinal peptide (VIP) does increase insulin levels. In fact, in vivo, VIP administration leads to a simultaneous increase in both blood glucose and insulin.
This effect is due to VIP's ability to stimulate insulin secretion from pancreatic beta cells. While the precise mechanisms are complex and involve several signaling pathways, VIP's interaction with receptors on beta cells triggers a cascade of events that ultimately result in the release of stored insulin into the bloodstream.
Here's a breakdown of the process:
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VIP Binds to Receptors: VIP binds to specific receptors on the surface of pancreatic beta cells. These receptors are G protein-coupled receptors (GPCRs).
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Activation of Signaling Pathways: Binding to the receptor activates intracellular signaling pathways, notably the cAMP/PKA pathway.
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Increased Insulin Secretion: Activation of these pathways leads to increased insulin exocytosis, meaning the release of insulin from vesicles within the beta cells.
The increase in blood glucose alongside insulin suggests that VIP might also influence glucose metabolism through other mechanisms, or that the released insulin is prompting glucose uptake.
In summary, VIP is a known stimulator of insulin secretion, leading to increased insulin levels in the blood.
