Stimulation of acetylcholine or dopamine receptors in the nucleus accumbens differentially alters dopamine release in the striatum of freely moving rats

Abstract

The present study examined whether unilateral stimulation of acetylcholine or dopamine receptors in the nucleus accumbens induces an asymmetry in dopamine transmission in the ventrolateral striatum. For this purpose, a microdialysis technique was used to measure dopamine release in both sides of the ventrolateral striatum following unilateral injections of carbachol (5 ¿¿g/0.5 j j l \ ) or a mixture of dopamine Dj and dopamine D 2 receptor agonists (l-phenyl-2,3,4,5-tetrahydro-ltf-3-benzazepine-7,8-diol 5 fig + quinpirole 10 ¿¿g/0.5 /xl) into the nucleus accumbens. The results show that carbachol injection increased dopamine release in the ipsilateral striatum without changing dopamine release in the contralateral striatum, whereas the dopamine D , / D 2 receptor agonist mixture injected unilaterally into the nucleus accumbens produced an increase followed by a decrease in dopamine release in the ipsilateral striatum, but only a decrease in dopamine release in the contralateral striatum. The biochemical effects of the cholinergic treatment greatly outlasted the drug-induced contralateral turning, whereas the biochemical effects of the dopaminergic treatment showed a good correlation with the drug-induced contralateral turning. The present study provides biochemical evidence that unilateral stimulation of acetylcholine or dopamine receptors in the nucleus accumbens elicits an asymmetry in dopaminergic activity in the ventrolateral striatum. The present study also provides biochemical evidence that two distinct neural substrates are involved in the effects of cholinergic and dopaminergic manipulation of the nucleus accumbens.

Contralateral turning elicited by unilateral stimulation of dopamine D2 and D1 receptors in the nucleus accumbens of rats is due to stimulation of these receptors in the shell, but not the core, of this nucleus

“…Recently, it has been found that this type of turning when elicited from the nucleus accumbens is inhibited by blockade of dopamine receptors in the ventrolateral striatum (Saigusa et al 1993(Saigusa et al , 1995. Moreover, the accumbens stimulation also enhances dopamine release in that part of the striatum (Koshikawa et al 1996). These data strongly suggest that the turning elicited from the shell is somehow funnelled via the ventrolateral striatum.…”