TY - JOUR
T1 - Glucose modulates rat substantia nigra GABA release in vivo via ATP-sensitive potassium channels
AU - During, Matthew J.
AU - Leone, Paola
AU - Davis, Karen E.
AU - Kerr, David
AU - Sherwin, Robert S.
PY - 1995/5
Y1 - 1995/5
N2 - Glucose modulates beta cell insulin secretion via effects on ATP-sensitive potassium (KATP) channels. To test the hypothesis that glucose exerts a similar effect on neuronal function, local glucose availability was varied in awake rats using microdialysis in the substantia nigra, the brain region with the highest density of KATP channels. 10 mM glucose perfusion increased GABA release by 111±42%, whereas the sulfonylurea, glipizide, increased GABA release by 84±20%. In contrast, perfusion of the KATP channel activator, lemakalim, or depletion of ATP by perfusion of 2-deoxyglucose with oligomycin inhibited GABA release by 44±8 and 45±11%, respectively. Moreover, the inhibition of GABA release by 2-deoxyglucose and oligomycin was blocked by glipizide. During systemic insulin-induced hypoglycemia (1.8±0.3 mM), nigral dialysate GABA concentrations decreased by 49±4% whereas levels of dopamine in striatal dialysates increased by 119±18%. We conclude that both local and systemic glucose availability influences nigral GABA release via an effect on KATP channels and that inhibition of GABA release may in part mediate the hyperexcitability associated with hypoglycemia. These data support the hypothesis that glucose acts as a signaling molecule, and not simply as an energy-yielding fuel, for neurons.
AB - Glucose modulates beta cell insulin secretion via effects on ATP-sensitive potassium (KATP) channels. To test the hypothesis that glucose exerts a similar effect on neuronal function, local glucose availability was varied in awake rats using microdialysis in the substantia nigra, the brain region with the highest density of KATP channels. 10 mM glucose perfusion increased GABA release by 111±42%, whereas the sulfonylurea, glipizide, increased GABA release by 84±20%. In contrast, perfusion of the KATP channel activator, lemakalim, or depletion of ATP by perfusion of 2-deoxyglucose with oligomycin inhibited GABA release by 44±8 and 45±11%, respectively. Moreover, the inhibition of GABA release by 2-deoxyglucose and oligomycin was blocked by glipizide. During systemic insulin-induced hypoglycemia (1.8±0.3 mM), nigral dialysate GABA concentrations decreased by 49±4% whereas levels of dopamine in striatal dialysates increased by 119±18%. We conclude that both local and systemic glucose availability influences nigral GABA release via an effect on KATP channels and that inhibition of GABA release may in part mediate the hyperexcitability associated with hypoglycemia. These data support the hypothesis that glucose acts as a signaling molecule, and not simply as an energy-yielding fuel, for neurons.
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U2 - 10.1172/JCI117935
DO - 10.1172/JCI117935
M3 - Article
C2 - 7738204
AN - SCOPUS:0028951455
SN - 0021-9738
VL - 95
SP - 2403
EP - 2408
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 5
ER -