CCK receptor antagonist L-365,260 potentiated electroacupuncture analgesia in Wistar rats but not in audiogenic epileptic rats.
Cholecystokinin octapeptide (CCK-8) has been shown to be a neuropeptide with potent anti-opioid activity. Previous studies have shown that central administration of nanogram dose of CCK-8 totally abolished morphine analgesia in the rat, an effect mediated by CCK-B receptor in central nervous system. In the present study CCK-B antagonist L-365,260 was injected intracerebroventricularly (icv) to Wistar rats to see its effect on the analgesic effect induced by electroacupuncture (EA) stimulation. A marked potentiation of EA-induced analgesia was observed. The degree of potentiation depends on the frequency of EA used, with a rank order of 100 Hz > 15 Hz = 2/15 Hz > > 2 Hz. In a strain of rat with acoustically evoked epileptic seizure (P77PMC rats), an extra-ordinarily strong analgesic effect was produced in response to 100 Hz EA stimulation, which was similar to that in Wistar rats pre-treated with L-365,260. However, L-365,260 was not effective in potentiating EA analgesia in P77PMC rats. The results suggest that (1) high frequency EA is more likely to increase the release of CCK-8 in CNS as compared to low frequency EA, and (2) P77PMC rats may have a functional defect of the central CCK neurons in the nature of either a low CCK content or a reduced rate of release of CCK-8 in the CNS.
Chen
X H
XH
Department of Physiology, Beijing Medical University.
Han
J S
JS
Huang
L T
LT
D015667:Acupuncture Analgesia; D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology*; D015671:Electroacupuncture; D007276:Injections, Intraventricular; D010671:Phenylurea Compounds; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors*; D013045:Species Specificity
D001570:Benzodiazepinones; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; C058121:L 365260