Cholecystokinin and its antagonist lorglumide respectively attenuate and facilitate morphine-induced inhibition of C-fiber evoked discharges of dorsal horn nociceptive neurons.
Extracellular single unit recordings were made from dorsal horn nociceptive neurons of intact, urethane-anesthetized rats during controlled electrical stimulation of the hind paw. Neither local superfusion of cholecystokinin octapeptide (CCK; 6.4 pmol to 20 nmol) nor the CCK antagonist lorglumide (LGM; 145 fmol to 145 pmol) significantly altered A- or C-fiber evoked firing or spontaneous activity. Pretreatment with CCK, however, significantly attenuated, whereas LGM enhanced, morphine-induced inhibition of C-evoked firing. These findings provide further evidence that CCK functions as a selective antagonist of opioid-induced analgesia.
Kellstein
D E
DE
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Price
D D
DD
Mayer
D J
DJ
D000818:Animals; D002766:Cholecystokinin / Q000037:antagonists & inhibitors*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D011377:Proglumide / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D009020:Morphine; D002766:Cholecystokinin; D011377:Proglumide; C048181:lorglumide; D012844:Sincalide