MUSCARINIC CHOLINERGIC BINDING IN STRIATAL AND MESOLIMBIC AREAS OF THE RAT - REDUCTION BY 6-HYDROXYDOPA

The pilocarpine-induced catalepsy and the specific binding of [3H]quinuclidinyl benzilate ([3H]QNB) in synaptic membranes were investigated in the adult rat neonatally treated with 6-hydroxydopa (6-OHDOPA). An i.p. administration of pilocarpine (75-150 mg/kg) elicited less catalepsy in the 6-OHDOPA-treated rats than in the controls. The specific binding of [3H]QNB in the striatal or mesolimbic homogenates proved to be saturable. In addition, treatment with 6-OHDOPA caused a significant reduction in Bmax values of [3H]QNB binding in both regions but did not alter the KD values as compared with those of the controls. These results suggest that neonatal treatment with 6-OHDOPA induces a muscarinic-cholinergic hyposensitivity in the rat brain which is probably due to the decrease in the number of muscarinic-cholinergic receptors in the striatal and/or mesolimbic areas. © 1979.