Chronic uridine treatment reduces the level of [3H]spiperone-labelled dopamine receptors and enhances their turnover rate in striatum of young rats: relationship to dopamine-dependent behaviours.

The effect was studied of chronic uridine treatment on the recovery of striatal D-2 dopamine (DA) receptors after their irreversible blockade by N-ethoxycarbonyl-2-ethoxy-I,2-dihydroquinoline (EEDQ) in young (40 days old) and adult (14 months old) male rats using [3H]spiperone as radioligand. Chronic uridine treatment (15 mg kg-1 day-1, i.p., 14 days) causes a reduction of [3H]spiperone binding sites in striatum of young rats. This treatment also produces an increase in the rate of recovery of striatal [3H]spiperone-labelled DA receptors in young, but not in adult rats. Catalepsy and exploratory locomotor activity, two behaviours associated with blockade versus activation of DA receptors, were evaluated in the same rats. The behavioural recovery from the EEDQ-induced syndrome is more rapid in the young rats treated with uridine than in the saline-treated group. The behavioural recovery in old rats was not affected by chronic uridine treatment. Thus, in young rats the pyrimidine nucleoside uridine may modulate the steady state and the turnover rate of striatal D-2 DA receptors.