Hyperglucagonemia induced in mice by tryptamine: involvement of the peripheral 5-HT2 receptors.

The effects of an indoleamine, tryptamine, on plasma glucagon levels were investigated in mice. Tryptamine induced dose-related increases in plasma glucagon levels. The hyperglucagonemia effects of tryptamine were completely antagonized by methysergide and ketanserin which have a high affinity to 5-HT2 receptors. In addition, the peripheral 5-HT2 receptor antagonist, xylamidine, also strongly inhibited tryptamine-induced hyperglucagonemia. Our results indicate that the peripheral 5-HT2 receptors mediate the increase in plasma glucagon levels induced by tryptamine and that these receptors may have a role in the control of glucagon secretion.