Cholecystokinin-octapeptide antagonizes morphine analgesia in periaqueductal gray of the rat.
The analgesic effect of systemic morphine (5 mg/kg, s.c.) was dose-dependently antagonized by CCK-8 administered to the periaqueductal gray (PAG) of the rat. This effect could be reversed by proglumide, a CCK-receptor antagonist. The effect of morphine analgesia was potentiated by proglumide administered to PAG. These results are compatible with the notion that PAG is a strategic site where CCK-8 exerts an antiopioid activity.
Li
Y
Y
Department of Physiology, Beijing Medical University, People's Republic of China.
Han
J S
JS
D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D010487:Periaqueductal Gray / Q000187:drug effects / Q000503:physiopathology*; D011377:Proglumide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology*
D009020:Morphine; D011377:Proglumide; D012844:Sincalide