Cholecystokinin B receptor antagonism enhances the ability of a low dose of morphine to reduce c-Fos expression in the spinal cord of the rat.
Three hours after intraplantar carrageenin (6 mg/150 microliters) Fos-like immunoreactivity was predominantly observed in the superficial and deep laminae of the L4-L5 segments of the dorsal horn of the spinal cord in the rat. The total number of Fos-like immunoreactive neurons was equally divided between the superficial (laminae I-II) and deep laminae (laminae V-VI), 99 +/- 3 and 102 +/- 7 Fos-like immunoreactive neurons per section, respectively. In the absence of carrageenin stimulation a negligible number of Fos-like immunoreactive neurons were observed. Pre-administered systemic morphine (0.3 mg/kg) did not significantly influence the total number of Fos-like immunoreactive neurons 3 h after carrageenin. However, pre-administration of a higher dose of morphine (3 mg/kg) significantly reduced the total number of Fos-like immunoreactive neurons (28 +/- 8% reduction, P < 0.001, as compared with control carrageenin Fos-like immunoreactive expression), with this effect being equally divided between the superficial and deep laminae (29 +/- 5 and 29 +/- 6% reduction, respectively, P < 0.001, as compared with control carrageenin Fos-like immunoreactive expression, for both). Pre-administration of the selective cholecystokinin B receptor antagonist, L-365-260 (0.2 mg/kg), alone did not influence the total number of Fos-like immunoreactive neurons 3 h after carrageenin.(ABSTRACT TRUNCATED AT 250 WORDS)
Chapman
V
V
Physiopharmacologie du Système Nerveux, INSERM U.161, Paris, France.
Honoré
P
P
Buritova
J
J
Besson
J M
JM
D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D007150:Immunohistochemistry; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D010671:Phenylurea Compounds; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors* / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects*
D001570:Benzodiazepinones; D010671:Phenylurea Compounds; D016760:Proto-Oncogene Proteins c-fos; D011949:Receptors, Cholecystokinin; C058121:L 365260; D009020:Morphine