Possible involvement of the cholinergic system in hormonal secretion by the perfused pancreas from ventromedial-hypothalamic lesioned rats

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Abstract
Total arginine-induced secretion of insulin, glucagon and somatostatin was studied during a 20 min period in isolated perfused pancreases from control and non-hyperphagic ventromedial hypothalamic (VMH) lesioned rats. Compared to controls pancreases from VMH-lesioned rats secreted more insulin (82±13ng vs 36±9ng) and more glucagon (130±23ng vs 73±14ng) but less somatostatin (0.58±0.18ng vs 1.12±0.14ng). These abnormalities were restored to normal by perfusion with atropine (25 μmol/l). Pancreases of both groups were perfused with the cholinergic agonist methacholine (100 μmol/l). Again pancreases from VMH-lesioned rats secreted more insulin (157±19ng vs 33±6ng) and more glucagon (95±13 ng vs 57±9 ng) but less somatostatin (0.80±0.15 ng vs 1.30±0.18 ng). These results support the concept that, in pancreases isolated from VMH-lesioned rats increased “cholinergic activity” may prevail via increased release of endogenous acetylcholine from islet-postsynaptic ganglion cells together with increased numbers of muscarinic receptors on postsynaptic ganglion cells as well as on endocrine cells.