Abstract
Activity of opioids in cats was assessed by employing the tail-flick method. Microinjection of morphine (100 μg) or etorphine (2.5 μg) into the ventrolateral periaqueductal gray (VLPAG) region resulted in significant analgesia. Smaller doses of morphine (10 and 50 μg) or etorphine (0.62 and 1.25 μg) were without significant effect. Methadone likewise produced no significant analgesic action in doses as large as 360 μg 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. © 1984.
| Original language | American English |
|---|---|
| Journal | Neuropharmacology |
| Volume | 23 |
| State | Published - Jan 1 1984 |
Keywords
- Animal
- Cats
- Injections
- Male
- Microinjections
- Periaqueductal Gray
- Reaction Time
- Subcutaneous
- analgesia
- animal experiment
- autonomic nervous system
- cat
- central nervous system
- dose response
- drug administration
- drug antagonism
- drug comparison
- drug efficacy
- drug response
- etorphine
- feline analgesia
- intracerebral drug administration
- methadone
- methodology
- microinjection
- morphine
- naloxone
- naloxone reversal
- narcotics
- nonhuman
- pain
- subcutaneous drug administration
- tail-flick method
- therapy
- ventrolateral periaqueductal gray
Disciplines
- Medicine and Health Sciences