Opiate A and B receptors in the rat striatum

Studies involving binding of 3H-naloxone to crude synaptosomal fraction from the rat striatum have revealed that the striatum contains opiate receptors. Scatchard analysis data indicate that KD = 70.92 nM and Bmax = 0.37 pmole per milligram of proteins. The experiments carried out in the absence and presence of Na+ in the incubating medium have shown that morphine and azidomorphine behave as agonists of the opiate receptor in the striatum, while cyclopropylmethylazidomorphine acts as an antagonist. It is concluded that the striatal opiate receptors are predominantly of type B.