Effect of adrenergic and cholinergic neurotransmitters on insulin secretion from the pancreas of normal and diabetic rats

The effect of noradrenaline (NA), adrenaline (ADR), and acetylcholine (ACh) on insulin secretion from the isolated pancreas of normal and diabetic rats was examined using radioimmunoassay technique. Diabetes mellitus was induced by streptozotocin. Pancreatic tissue fragments of normal and diabetic rats were removed and incubated with different concentrations (10^-8, 10^-6, 10^-4 M) of NA, ADR and ACh. Insulin secretion into the supernatant was later determined by radioimmunoassay. NA at a concentration of 10^-8 M evoked a six-fold increase in insulin secretion from normal pancreatic tissue fragments compared to basal. NA induced a three-fold increase in insulin output from the pancreas of diabetic rats when compared to basal. ADR (10^-8 M) induced a three-fold increase in insulin secretion from isolated normal rat pancreas. In contrast, inhibition of insulin secretion was observed when ADR (10^-8, 10^-6, 10^-4 M) was incubated with pancreatic tissue fragments of diabetic rats. ACh evoked a six-fold increase in insulin secretion when incubated with normal rat pancreas tissue fragments at a concentration of 10^-8 M. Similarly, ACh (10^-4 M) evoked a two-fold increase in insulin secretion from the in vitro diabetic rat pancreas. In conclusion NA, ADR and ACh have potent secretagogue effect on insulin secretion from the pancreas of normal rat.