Analgesic effects of cyclazocine and morphine microinjected into the rat dorsomedial hypothalamus demonstrated by the bradykinin-induced flexor reflex test.
The analgesic effect of cyclazocine microinjected into the diencephalon of rats was studied by using the bradykinin-induced flexor reflex test. The dorsal portion of the medial hypothalamic area was sensitive to cyclazocine with respect to the production of analgesia (ED50 2.6 micrograms/rat). Microinjections of morphine into the same portion also produced a dose-dependent analgesic effect (ED50 2.5 micrograms/rat). As naloxone (0.9 mg/kg s.c.) antagonized both these analgesic effects, the findings suggest that the dorsal portion of the medial hypothalamic area of the rat is one of the primary target sites of analgesic drugs.
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D003496:Cyclazocine / Q000494:pharmacology*; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects*; D007033:Hypothalamus, Middle / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects*; D010146:Pain / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects
D009020:Morphine; D003496:Cyclazocine; D001920:Bradykinin