Effect of cholecystokinin octapeptide and ceruletide on release of acetylcholine from cerebral cortex of the rat in vivo.
The effect of cholecystokinin octapeptide (CCK-8) and its analogue, ceruletide on release of acetylcholine (ACh) from the cerebral cortex was investigated in urethane-anaesthetized and in unanaesthetized rats. Cholecystokinin octapeptide and ceruletide markedly stimulated output of ACh at doses of 1.5 and 5.0 micrograms/kg (i.p.), respectively. This effect was prevented by proglumide (160 mg/kg i.p.), a specific cholecystokinin receptor antagonist. At doses of 10 micrograms/kg (i.p.) and more, both CCK-8 and ceruletide decreased output of ACh from the cerebral cortex. The decrease was prevented by naloxone (1 mg/kg, s.c.), and replaced by a short-lasting increase. Cholecystokinin octapeptide and ceruletide appear therefore to affect the activity of cortical cholinergic fibres by acting upon both specific and opiate receptors. The interaction between CCK-8 and ceruletide, and opiate receptors either direct or through the release of endogenous opiates, was also demonstrated by the antagonism between ceruletide (1, 5 and 10 micrograms/kg, i.p.) and analgesia induced by morphine (5 mg/kg, s.c.), evaluated by the tail-flick test in the rat.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D002108:Ceruletide / Q000494:pharmacology*; D006993:Hypnotics and Sedatives; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects; D011377:Proglumide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology*
D006993:Hypnotics and Sedatives; D009270:Naloxone; D009020:Morphine; D002108:Ceruletide; D011377:Proglumide; D012844:Sincalide; D000109:Acetylcholine