Stress induced analgesia in frogs: a naloxone insensitive system.
Repeated algesiometric testing of frogs with acetic acid can, under certain circumstances, lead to a pronounced elevation of their nociceptive threshold. Analgesia is reliably induced if algesiometric testing is begun shortly after the animals are placed in the testing cages, but not if the animals are allowed 3 days in which to recover from the stress of transfer and to acclimate to the test environment. Naloxone at doses up to 10 mg/kg neither blocks nor reverses this form of stress-induced analgesia. These data indicate that frogs, like some mammals, can use non-opiate mechanisms to modulate either their perception of or response to noxious stimuli.
D000085:Acetates / Q000494:pharmacology; D000698:Analgesia; D000818:Animals; D004056:Differential Threshold; D009270:Naloxone / Q000494:pharmacology / Q000502:physiology*; D009619:Nociceptors / Q000187:drug effects; D011894:Rana pipiens / Q000502:physiology*; D013312:Stress, Physiological / Q000503:physiopathology*
D000085:Acetates; D009270:Naloxone