The failure of morphine to attenuate spinal cord nociceptive transmission through supraspinal actions in the cat.
Morphine sulphate was perfused between the third ventricle and cisterna magna in alpha-chloralose anaesthetized cats while recording from multireceptive dorsal horn neurones activated by peripheral noxious radiant heat. Morphine concentrations of 10(-5) and 10(-4) M were without effect, while 10(-3) M resulted in an increase in the spinal cord neuronal responses. The results do not support the notion that morphine activates a supraspinal mediated descending inhibition which antagonizes spinal cord nociceptive transmission.
D000818:Animals; D002415:Cats; D005260:Female; D006358:Hot Temperature; D007276:Injections, Intraventricular; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects*; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
D009020:Morphine