Effect of centrally administered enkephalins on carrageenin-induced paw oedema in rats.
Intracerebroventricularly (icv) administered met-enkephalin, leu-enkephalin, and morphine induced dose-related attenuation of carrageenin-induced acute paw oedema in rats. Naloxone (10 micrograms, icv) antagonized the anti-inflammatory effects of the enkephalins (20 micrograms) and morphine (20 micrograms), but itself induced an anti-inflammatory effect at a higher dose (50 micrograms, icv). The anti-inflammatory effects of the enkephalins, morphine, and the higher dose of naloxone were significantly inhibited by metyrapone, an inhibitor of endogenous corticoid synthesis. The icv-administered doses of the enkephalins and morphine induced insignificant inflammation-attenuating effects when administered i.p. Results suggest that the anti-inflammatory effects of the enkephalins and morphine are exerted through central opiate receptors. Furthermore, the inflammation-attenuating effects of these drugs and the higher dose of naloxone appear to be dependent upon endogenous corticoids, suggesting that activation of the hypothalamo-pituitary-adrenocortical axis may be involved.
Bhattacharya
S K
SK
Department of Pharmacology, Banaras Hindu University, Varanasi, India.
Saraswati
M
M
Sen
A P
AP
D000818:Animals; D001169:Arthritis, Experimental / Q000139:chemically induced / Q000517:prevention & control; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002351:Carrageenan; D004487:Edema / Q000139:chemically induced / Q000517:prevention & control*; D004743:Enkephalin, Leucine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005260:Female; D006614:Hindlimb; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D008297:Male; D008797:Metyrapone / Q000494:pharmacology; D009020:Morphine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D010913:Pituitary-Adrenal System / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D009270:Naloxone; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D009020:Morphine; D002351:Carrageenan; D008797:Metyrapone