Anticonvulsant effects of ipsilateral but not contralateral microinjections of the dopamine D2 agonist LY 171555 into the nucleus accumbens of amygdala-kindled rats

Recent radioligand binding studies demonstrated an increase in the density of dopamine D₂ receptors in the nucleus accumbens ipsilateral to the stimulating electrode in amygdala- or hippocampal-kindled rats. In the present study we examined the anticonvulsant effect of dopamine agonists by unilateral microinjections into the nucleus accumbens in rats kindled from the right basolateral amygdaloid nucleus. Microinjections of the D₂ agonist LY 171555 into the ipsilateral nucleus accumbens 15 min prior to the kindling stimulation in fully kindled rats decreased significantly kindling parameters such as seizure severity, seizure duration and afterdischarge duration, whereas the D₁ agonist SKF 38393 had no anticonvulsant effects. After ipsilateral microinjection of 40 pmol LY 171555, focal and generalized kindled seizures were totally blocked in almost 50% of the rats. The anticonvulsant effect of LY 171555 could be completely antagonised by systemic administration of the D₂ antagonist sulpiride. Microinjection of the D₁ or D₂ agonist into the nucleus accumbens contralateral to the stimulating electrode had no anticonvulsant effects. In accordance with other reports our data indicate a possible topographic limitation of D₂ receptor mediated anticonvulsant effects to specific regions of the basal ganglia.