Evidence for noncholinergic ganglionic neural stimulation of B cell secretion

Insulin levels increase after 2-deoxyglucose (2DG) administration in dogs. This observation is in contrast to the decrease in insulin level post-2DG in baboons and rabbits. To evaluate a possible neural mechanism mediating this increase in insulin level, we studied normal mongrel dogs with 2DG alone, 2DG during ganglionic blockade, beta-adrenergic blockade, and postganglionic parasympathetic blockade. There was an increase in plasma epinephrine, norepinephrine, pancreatic polypeptide, insulin, and glucose post-2DG alone. During ganglionic blockade, the increase in epinephrine, norepinephrine, and pancreatic polypeptide post-2DG was completely abolished, verifying ganglionic blockade of sympathetic and parasympathetic pathways, respectively. Despite this, ganglionic blockade failed to abolish the insulin rise after 2DG. Postganglionic parasympathetic blockade did not change the insulin rise after 2DG. However, beta-adrenergic blockade completely abolished the insulin rise after 2DG. The above data suggests that 1) the insulin rise post-2DG is beta-adrenergic but 2) the ganglionic neurotransmitter mediating the 2DG-induced insulin rise during ganglionic blockade is noncholinergic (possibly peptidergic).