Intracerebroventricular administration of angiotensin II attenuates morphine-induced analgesia in mice.
The central effect of angiotensin II on the analgesic action of morphine in mice was investigated using the tail-pinch and hot plate tests. Angiotensin II (0.1-10 pmol), given intracerebroventricularly (i.c.v.), had no effect on the nociceptive sensitivity but did produce a dose-dependent attenuation of the morphine-induced analgesia. A specific angiotensin II antagonist, Saralasin (1 pmol), which in itself had no analgesic effect, significantly potentiated the morphine-induced analgesia. These results suggest that angiotensin II probably plays the physiological role of an anti-opioid substance in pain-modulating systems in the brain.
D000698:Analgesia; D000804:Angiotensin II / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors*; D011930:Reaction Time / Q000187:drug effects; D012504:Saralasin / Q000494:pharmacology
D000804:Angiotensin II; D009020:Morphine; C014622:angiotensin II, Ile(8)-; D012504:Saralasin