Exposure to a cat produces opioid analgesia in rats.
Two experiments were conducted to test the prediction that rats should react with reduced sensitivity/reactivity to nociceptive stimulation in the presence of a cat. In Experiment 1, naloxone or saline was administered, and rats were exposed to no stimulus, a novel stimulus, or a cat. In Experiment 2, rats were exposed to either no stimulus or a cat, and naltrexone was administered. In both experiments, rats tested in the presence of the cat showed a significant reduction in sensitivity/reactivity to a skin-irritating formalin injection. Naltrexone reversed this analgesia.
D000818:Animals; D004723:Endorphins / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D005260:Female; D009270:Naloxone; D009271:Naltrexone; D009420:Nervous System / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000502:physiology
D004723:Endorphins; D009270:Naloxone; D009271:Naltrexone