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Glucose-regulated dopamine release from substantia nigra neurons
1Neurology Service (127C), VA Medical Center, 385 Tremont Ave., E. Orange, NJ 17018, USA. levin@umdnj.edu
Brain Research
|August 29, 2000
Summary
Altering glucose levels in the substantia nigra (SN) impacts dopamine (DA) release in the striatum. This suggests glucose influences motor activity and food intake through SN DA neurons.
Area of Science:
- Neuroscience
- Endocrinology
- Neuropharmacology
Background:
- Glucose is known to modulate neuronal activity in the substantia nigra (SN).
- It affects dopamine (DA) and GABA release via ATP-sensitive potassium channels (K(ATP)).
Purpose of the Study:
- To investigate how altering SN glucose levels affects striatal DA release.
- To explore the role of GABAergic inhibition in this glucose-mediated modulation.
Main Methods:
- Microdialysis probes were used in the SN and striatum of Sprague-Dawley rats.
- Varying concentrations of glucose (20 mM, 50 mM, 100 mM) were infused into the SN.
- The GABA(A) antagonist bicuculline and glipizide were also administered.
Main Results:
- SN glucose infusion caused dose-dependent, transient changes in striatal DA efflux.
- 100 mM glucose led to a sustained increase in DA release, enhanced by bicuculline.
- Bicuculline alone increased DA efflux, indicating tonic GABA inhibition of DA neurons.
Conclusions:
- Striatal DA release is significantly modulated by SN glucose levels.
- Glucose likely acts on K(ATP) channels in SN DA neurons and GABA terminals.
- This mechanism may link glucose levels to the regulation of motor activity and food intake.