DOPAMINE D-2-RECEPTORS REGULATE NEUROTENSIN RELEASE FROM NUCLEUS-ACCUMBENS AND STRIATUM AS MEASURED BY IN-VIVO MICRODIALYSIS

The present study was undertaken to examine the role of dopamine D-2-r eceptors in the regulation of the neurotensin release. Through a modif ication of the methods described by Maidment et al. (Neuroscience, 45 (1991) 81-93), we have developed a highly reproducible method of measu ring changes in extracellular NT in the striatum and nucleus accumbens by in vivo microdialysis in awake animals. It was observed that calci um-dependent release of NT was evoked in both structures by infusing a high concentration of potassium. In addition, systemic administration of the D-2 agonist quinpirole (5 mg/kg) induced a rapid increase of a pproximately 200% in extracellular NT levels in the lateral caudate an d 30-40% in the nucleus accumbens. Conversely, treatment with the D-2 antagonist eticlopride (0.5 mg/kg) reduced extracellular NT in the med ial anterior caudate and nucleus accumbens 20-30%, but had no effect i n the lateral anterior caudate. These data demonstrate for the first t ime that D-2-receptors are important in the dopaminergic regulation of extrapyramidal and limbic NT release in conscious animals.