Feline analgesia following central administration of opioids
Activity of opioids in cats was assessed by employing the tail-flick method. Microinjection of morphine (100 Î¼g) or etorphine (2.5 Î¼g) into the ventrolateral periaqueductal gray (VLPAG) region resulted in significant analgesia. Smaller doses of morphine (10 and 50 Î¼g) or etorphine (0.62 and 1.25 Î¼g) were without significant effect. Methadone likewise produced no significant analgesic action in doses as large as 360 Î¼g in the ventrolateral periaqueductal gray. Rank order potency, i.e. etorphine > morphine >> methadone, was similar following systemic administration. Increased latency of tail-flick response after injection of etorphine was diminished by administration of naloxone, either systemically or centrally, thus indicating a specific opiate-mediated response. Â© 1984.
Ossipov, M. H.; Goldstein, Frederick J.; and Malseed, R. T., "Feline analgesia following central administration of opioids" (1984). PCOM Scholarly Papers. 1334.