Potential role for AMP-activated protein kinase in hypoglycemia sensing in the ventromedial hypothalamus.
The mechanisms by which specialized glucose-sensing neurons within the hypothalamus are able to detect a falling blood glucose remain largely unknown but may be linked to some gauge of neuronal energy status. We sought to test the hypothesis that AMP-activated protein kinase (AMPK), an intracellular kinase purported to act as a fuel sensor, plays a role in hypoglycemia sensing in the ventromedial hypothalamus (VMH) of the Sprague-Dawley rat by chemically activating AMPK in vivo through bilateral microinjection, before performing hyperinsulinemic-hypoglycemic or hyperinsulinemic-euglycemic clamp studies. In a subgroup of rats, H3-glucose was infused to determine glucose kinetics. The additional chemical activation by AICAR of AMPK in the VMH during hypoglycemia markedly reduced the amount of exogenous glucose required to maintain plasma glucose during hypoglycemia, an effect that was almost completely accounted for by a three- to fourfold increase in hepatic glucose production in comparison to controls. In contrast, no differences were seen between groups in hypoglycemia-induced rises in the principal counterregulatory hormones. In conclusion, activation of AMPK within the VMH may play an important role in hypoglycemia sensing. The combination of hypoglycemia- and AICAR-induced AMPK activity appears to result in a marked stimulus to hepatic glucose counterregulation.
McCrimmon
Rory J
RJ
Department of Internal Medicine and Endocrinology, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
Fan
Xiaoning
X
Ding
Yuyan
Y
Zhu
Wanling
W
Jacob
Ralph J
RJ
Sherwin
Robert S
RS
D000620:Aminoimidazole Carboxamide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000097:blood; D015309:Glucose Clamp Technique; D006946:Hyperinsulinism; D007003:Hypoglycemia / Q000503:physiopathology*; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D012265:Ribonucleotides / Q000008:administration & dosage / Q000494:pharmacology; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D005934:Glucagon; D017868:Cyclic AMP-Dependent Protein Kinases; C031143:AICA ribonucleotide; D009638:Norepinephrine; D004837:Epinephrine