We investigated the effects of chronic
AMP-activated kinase (AMPK) activation in the hypothalamus on energy and
glucose metabolism in 90% pancreatectomized diabetic rats. Diabetic rats fed a high fat diet were divided into 3 groups and intracerebroventricular (ICV) administered with one of the following: 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (
AICAR, AMPK activator; 80 μg/day), AICAR+compound C (AMPK inhibitor; 6.2 μg/day), or an artificial cerebrospinal fluid (control) by means of osmotic pumps for 4 weeks. In the hypothalamus, central
AICAR activated the phosphorylation of AMPK whereas adding compound C suppressed the activation.
AICAR increased
body weight and epididymal and retroperitoneal fat mass by increasing energy intake for the first 2 weeks and decreasing energy expenditure, whereas compound C reversed the
AICAR effect on energy metabolism. Indirect calorimetry revealed that ICV-
AICAR decreased
carbohydrate oxidation, but not fat oxidation, compared to the control. During euglycemic hyperinsulinemic clamp, central
AICAR increased hepatic
glucose output at hyperinsulinemic states. ICV-
AICAR increased expressions of hepatic genes involved in
fatty acid synthesis and decreased expression of hepatic genes related to thermogenesis whereas compound C nullified the
AICAR effect. Insulin secretion in the first and second phases decreased in
AICAR-treated rats at hyperglycemic clamp, but compound C nullified the decrease. However, central
AICAR did not alter β-cell mass via its proliferation or apoptosis. In conclusion, chronic hypothalamic AMPK activation impaired energy metabolism and
glucose homeostasis by increasing food intake, increasing hepatic
glucose output and decreasing insulin secretion in diabetic rats. The impairment of energy and
glucose homeostasis by AMPK activation was nullified by an AMPK inhibitor.