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Cholinergic agonists prime the beta-cell to glucose stimulation
W S Zawalich1, K C Zawalich, H Rasmussen
1Yale University School of Nursing, New Haven, Connecticut 06536-0740.
Endocrinology
|November 1, 1989
Summary
Cholinergic agonists like carbachol stimulate insulin release and prime pancreatic beta-cells. This priming enhances insulin secretion in response to glucose and other stimuli, highlighting vagal nerve
Area of Science:
- Endocrinology
- Cell Biology
- Neuroscience
Background:
- Cholinergic agonists play a role in regulating insulin secretion.
- Phosphoinositide hydrolysis is a key signaling pathway in beta-cells.
- The vagus nerve influences pancreatic islet function.
Purpose of the Study:
- To investigate the effects of cholinergic agonists on insulin release.
- To determine if cholinergic stimulation primes beta-cells to glucose.
- To explore the role of phosphoinositide hydrolysis in this process.
Main Methods:
- Perifusion of pancreatic islets with carbachol or acetylcholine.
- Measurement of insulin secretion.
- Quantification of phosphoinositide hydrolysis via [3H]inositol efflux and inositol phosphate accumulation.
- Assessment of beta-cell sensitization to glucose, tolbutamide, and arginine.
Main Results:
- Carbachol (1 mM) evoked insulin release at 7 mM glucose but not 2.75 mM glucose.
- Carbachol stimulated phosphoinositide hydrolysis at both glucose concentrations.
- Pre-exposure to carbachol dose-dependently sensitized islets to 7.5 mM glucose, tolbutamide, and arginine.
- Sensitization occurred rapidly and persisted after agonist removal.
- Acetylcholine induced similar sensitization.
Conclusions:
- Cholinergic stimulation enhances phosphoinositide hydrolysis but does not initiate sustained insulin secretion at low glucose.
- This hydrolysis sensitizes islets to subsequent stimuli, including glucose.
- Vagal stimulation may regulate insulin secretion primarily through this sensitization mechanism.