Role of nitric oxide in catalepsy and hyperthermia in morphine-dependent rats.
The possible involvement of nitric oxide (NO) in morphine-induced catalepsy and hyperthermia was studied in morphine-dependent rats. Four days repeated injection regimen was used to induce morphine dependence, which was assessed by naloxone challenge (0.5 mg x kg(-1), s.c.). Pretreatment of rats with the NO synthase inhibitor, N(G)-nitro-L-arginine (L-NA, 8 mg x kg(-1) twice daily, i.p.) potentiated the cataleptic response of morphine as shown by a rightward shift in the morphine-log dose-response curve. Prior treatment of rats with the NO precursor, L-arginine (200 mg x kg(-1), twice daily, i.p.) abolished the potent effect of L-NA and restored the cataleptic scores to levels similar to those of morphine-dependent rats. The same dose of L-NA significantly blocked morphine-induced hyperthermia at the dose levels of morphine (15-105 mg x kg(-1)) and this effect was reversed by L-arginine. These data provide the first experimental evidence that NO is involved in morphine induced catalepsy and hyperthermia and demonstrated that blockade of NO synthesis may suggest a dangerous interaction with opioids in the control of motor function.
Afify
E A
EA
Department of Pharmacology, Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt. Afify001@hotmail.com
Daabees
T T
TT
Gabra
B H
BH
Abou Zeit-Har
M S
MS
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002375:Catalepsy / Q000139:chemically induced*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005334:Fever / Q000139:chemically induced*; D008297:Male; D009020:Morphine / Q000009:adverse effects*; D009021:Morphine Dependence / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000009:adverse effects*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D051381:Rats; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology
D004791:Enzyme Inhibitors; D009292:Narcotic Antagonists; D009294:Narcotics; D019335:Nitroarginine; D009569:Nitric Oxide; D009270:Naloxone; D009020:Morphine; D001120:Arginine; D019001:Nitric Oxide Synthase