TISSUE-SPECIFIC REDUCTION OF GALANIN CONTENT IN THE PANCREAS IN ALLOXAN DIABETES IN THE MOUSE

Galanin inhibits insulin secretion and has been proposed to function a s a sympathetic neurotransmitter in the endocrine pancreas in some spe cies, for example in the dog. In this study, pancreatic and adrenal gl and galanin content were measured following experimental diabetes indu ced by alloxan in mice. Three days after administration of alloxan (70 mg kg-1, i.p.) in normal mice, pancreatic content of galanin-like imm unoreactivity (GLIR) was reduced to 65 +/- 11 % of that in untreated c ontrols (P < 0.01), whereas adrenal gland GLIR was unchanged. Similarl y, 8 days after alloxan administration, pancreatic GLIR was reduced (P < 0.002), whereas adrenal gland GLIR was unaffected. Pancreatic GLIR also inversely correlated with plasma glucose levels (r = - 0.5055, P < 0.005). To distinguish between the direct effects of alloxan vs. ind irect metabolic effects induced by the drug, alloxan-diabetic mice wer e treated with insulin twice daily, which normalized the plasma glucos e levels (7.6 +/- 0.3 mmol l-1). Pancreatic GLIR was then not signific antly different from controls. Thus pancreatic but not adrenal gland G LIR content is reduced in alloxan-induced diabetes in mice. The data s upport a role for galanin as a pancreatic sympathetic neurotransmitter which may participate in the metabolic alterations seen in alloxan di abetes in mice.