ACCUMBAL CORE: ESSENTIAL LINK IN FEED-FORWARD SPIRALING STRIATO-NIGRO-STRIATAL IN SERIES CONNECTED LOOP

摘要

The goal of the present study was to establish the behavioral role of the nucleus accumbens (Nacc) core in the feed-forward spiraling striato-nigro-striatal circuitry that transmits information from the Nacc shell toward the dorsal subregion of the neostriatum (DS) in freely moving rats. Unilateral injection of u-opioid receptor agonist [D-Ala2, N-Me-Phe4,Gly5-ol]-enkephalin (DAMGO; 1 and 2 ug), but not the delta~1-opioid receptor agonist [D-Pen2'5]-enkephalin (4 ug) or the delta2-opioid receptor agonist [D-Ala2,Glu4]-deltor-phin (2 ug), into the ventral tegmental area (VTA) produced contraversive circling in a dose-dependent manner. The effect of DAMGO was u-opioid receptor-specific, because the u-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Phe-Thr-NH2 (0.1 and 1 ug), which alone did not elicit any turning behavior, dose-dependently inhibited the effect of DAMGO. Injection of the dopamine D1/D2 receptor antagonist cis-(Z)-flupentixol (1 and 10 ug) into the Nacc shell ipsilaterally to the VTA significantly inhibited DAMGO (2 ug)-induced circling.