title: Morphine catalepsy in the rat: involvement of mu 1 (high affinity) opioid binding sites.
abstract: Since the proposal of multiple classes of opiate receptors, much effort has been devoted to understanding the subtypes mediating specific opioid actions. Using the irreversible antagonist naloxazone, we have established a role for the high affinity (mu 1) sites in analgesia. These sites also appear important in opiate catalepsy. Control rats showed dramatic catalepsy following a high dose of morphine sulfate (100 mg/kg, s.c.). Rats whose high affinity (mu 1) sites had been blocked with naloxazone 24 h earlier, on the other hand, showed no evidence of catalepsy (P less than 0.01). Accordingly, catalepsy appears to involve the same receptors as analgesia, the higher affinity (mu 1) sites.
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D011957:Receptors, Opioid / Q000187:drug effects*; D017450:Receptors, Opioid, mu
chemical_list: D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D009270:Naloxone; D009020:Morphine