C-type natriuretic peptide can modify the acute and chronic effects of morphine.
Different doses (0.2-200 ng) of C-type natriuretic peptide (CNP) were administered into the lateral brain ventricle, and morphine (5 mg/kg) was injected subcutaneously. The analgesic effect was measured in a tail-flick test, in CFLP mice. CNP administered centrally did not itself affect pain sensitivity, but it depressed the acute antinociceptive effect of morphine 30 min after icv (0.2, 2 or 20 ng) CNP administration and the 2 and 20 ng doses also decreased this action after 60 min. CNP in a 0.2 or 200 ng dose blocked the development of acute tolerance to morphine after 30 min, as did the 200 ng dose at 60 min. CNP in a 0.2 ng dose blocked the development of chronic tolerance to morphine after 30 min, but there was no effect at 60 min. Morphine withdrawal signs were studied by injecting naloxone (1 mg/kg sc). There was no significant difference in symptoms between the tolerant group and the animals treated with CNP.
Department of Pathophysiology, Albert Szent-Györgyi Medical University, Szeged, Hungary.
E
E
Babarczy
Z
Z
Vízi
G
G
Tóth
G
G
Telegdy
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology*; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D011506:Proteins / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome; D013997:Time Factors
D009419:Nerve Tissue Proteins; D011506:Proteins; D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009020:Morphine; D009320:Atrial Natriuretic Factor