[Cholecystokinin octapeptide (CCK-8) antagonizes morphine analgesia in amygdala of the rat].
CCK-8 administered bilaterally to the amygdala at 0.1-1.0 ng dose-dependently antagonized the analgesia induced by morphine (4 mg/kg, s. c.) as measured by the changes in tail flick latency (TFL). This effect of CCK-8 could be reversed by Devazepide, a CCK-A receptor antagonist dose-dependently at 50 ng and 200 ng, and by L-365, 260, a CCK-B receptor antagonist at 5 ng and 8 ng administered to the same site. The effect of morphine analgesia was potentiated by 200 ng Devazepide or 8 ng L-365, 260 administered bilaterally to amygdala. Devazepide and L-365, 260 per second showed no significant influence on basal TFL. The results indicate that amygdala is a strategic site where CCK-8 exerts an antiopioid activity. Since the effect of L-365, 260 was 25 times more potent than Devazepide, it suggests that the anti-opiod effect of CCK in amygdala is mediated by CCK-B receptors.
Pu
S F
SF
Department of Physiology, Beijing Medical University.
Han
J S
JS
D000679:Amygdala / Q000502:physiology*; D000698:Analgesia; D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D002766:Cholecystokinin / Q000037:antagonists & inhibitors; D020109:Devazepide; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors*; D010671:Phenylurea Compounds; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors; D012844:Sincalide / Q000494:pharmacology*
D001570:Benzodiazepinones; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; C058121:L 365260; D009020:Morphine; D002766:Cholecystokinin; D020109:Devazepide; D012844:Sincalide