title: Effects of a high fat diet and electric stress on adenylate cyclase activity and insulin release in isolated islets of Langerhans.
abstract: The effects of glucagon and epinephrine on adenylate cyclase activity in homogenates of isolated islets and insulin release were studied in rats fed on either a control or a high fat diet for 12 weeks. Rats were divided into non-stress group and stress group. Rats in stress groups received electrical shocks (1 hr/day) for the last 3 weeks of the experimental period. Islet adenylate cyclase activity was measured by the conversion of [2-3H]ATP to cyclic [3H]AMP. While the basal activity of adenylate cyclase was increased by stress, it was reduced by the high fat diet. In the presence of a low glucose concentration, the adenylate cyclase activity was higher in non-stress groups rather than in stress groups. However, the adenylate cyclase activity was not altered by an increase in glucose concentration. Characteristically, the adenylate cyclase activity in fat diet-stress group was reduced by 16.7 mM glucose and glucose-stimulated insulin release was low. Stress enhanced glucagon-stimulated adenylate cyclase activity, which was reduced by the high fat diet. The effect of glucagon on adenylate cyclase activity was similar to that on insulin release. Epinephrine (10-6M) did not after the adenylate cyclase activity in all four groups. It is concluded that a decrease of glucose-stimulated insulin release produced by the combined actions of a high fat diet and electric stress may involve at least partly the inhibition of adenylate cyclase-cyclic AMP system activated by glucose itself.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D004560:Electricity; D004837:Epinephrine / Q000494:pharmacology; D005934:Glucagon / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000503:physiopathology*
chemical_list: D004041:Dietary Fats; D007328:Insulin; D005934:Glucagon; D000262:Adenylyl Cyclases; D005947:Glucose; D004837:Epinephrine