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Hypothalamic AMP-activated protein kinase activation with AICAR amplifies counterregulatory responses to hypoglycemia in a rodent model of type 1 diabetes.


ABSTRACT: In nondiabetic rodents, AMP-activated protein kinase (AMPK) plays a role in the glucose-sensing mechanism used by the ventromedial hypothalamus (VMH), a key brain region involved in the detection of hypoglycemia. However, AMPK is regulated by both hyper- and hypoglycemia, so whether AMPK plays a similar role in type 1 diabetes (T1DM) is unknown. To address this issue, we used four groups of chronically catheterized male diabetic BB rats, a rodent model of autoimmune T1DM with established insulin-requiring diabetes (40 +/- 4 pmol/l basal c-peptide). Two groups were subjected to 3 days of recurrent hypoglycemia (RH), while the other two groups were kept hyperglycemic [chronic hyperglycemia (CH)]. All groups subsequently underwent hyperinsulinemic hypoglycemic clamp studies on day 4 in conjunction with VMH microinjection with either saline (control) or AICAR (5-aminoimidazole-4-carboxamide) to activate AMPK. Compared with controls, local VMH application of AICAR during hypoglycemia amplified both glucagon [means +/- SE, area under the curve over time (AUC/t) 144 +/- 43 vs. 50 +/- 11 ng.l(-1).min(-1); P < 0.05] and epinephrine [4.27 +/- 0.96 vs. 1.06 +/- 0.26 nmol.l(-1).min(-1); P < 0.05] responses in RH-BB rats, and amplified the glucagon [151 +/- 22 vs. 85 +/- 22 ng.l(-1).min(-1); P < 0.05] response in CH-BB rats. We conclude that VMH AMPK also plays a role in glucose-sensing during hypoglycemia in a rodent model of T1DM. Moreover, our data suggest that it may be possible to partially restore the hypoglycemia-specific glucagon secretory defect characteristic of T1DM through manipulation of VMH AMPK.

SUBMITTER: Fan X 

PROVIDER: S-EPMC2692788 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Hypothalamic AMP-activated protein kinase activation with AICAR amplifies counterregulatory responses to hypoglycemia in a rodent model of type 1 diabetes.

Fan X X   Ding Y Y   Brown S S   Zhou L L   Shaw M M   Vella M C MC   Cheng H H   McNay E C EC   Sherwin R S RS   McCrimmon R J RJ  

American journal of physiology. Regulatory, integrative and comparative physiology 20090408 6


In nondiabetic rodents, AMP-activated protein kinase (AMPK) plays a role in the glucose-sensing mechanism used by the ventromedial hypothalamus (VMH), a key brain region involved in the detection of hypoglycemia. However, AMPK is regulated by both hyper- and hypoglycemia, so whether AMPK plays a similar role in type 1 diabetes (T1DM) is unknown. To address this issue, we used four groups of chronically catheterized male diabetic BB rats, a rodent model of autoimmune T1DM with established insulin  ...[more]

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