Are pancreatic beta-cells under vagal control?

To elucidate the importance of cholinergic innervation for pancreatic beta-cells in vivo, atropine sulphate (0.2 mg/kg body weight) was subcutaneously injected into mice 4 times a day for 10 days. Control animals received 0.9% NaCl. Paraffin sections of the pancreas were stained for beta-cells with aldehyde fuchsin and for alpha-cells (glucagon cells) with silver according to Grimelius. Endocrine and exocrine cell nuclei were measured with an ocular screw micrometer. The light absorbance at 550 nm wave-length of aldehyde-fuchsin-stained islet sections was measured with a microscope photometer. Atropine caused no loss of body weight or apparent food consumption. The nuclei of beta-cells shrank significantly in response to atropine; A550 of islet surfaces showed a significant negative correlation to beta-cell nuclear size. Acinar cell nuclei near islets also became smaller after atropine treatment but to a lesser extent. No such change was observed in the alpha-cells. A trophic influence of the vagal nerve may be important for the long-term control of beta-cell function.