Analgesia induced by exposure to a novel environment in rats: effect of concurrent and post-training stressful stimulation.
Exposure of rats for 2 min to a new environment (a 50 X 25 X 25-cm box) induced a mild analgesia measured by the tail-flick method. Additional stressful stimuli (0.5 mA, 1.5-s footshocks, light flashes, or tones) presented during the 2-min exposure did not alter the analgesia. However, the postexposure presentation of light flashes or tones, for either 10 s or 2 min, while the animals were alone in a waiting cage, prevented the analgesic response. Similarly, placing the subjects with their conspecifics in the home cage for 2 min after the exposure prevented the analgesic response. The data suggest that the analgesia may represent a physiological correlate of novelty and that the response can be impaired by post-training treatments.
Netto
C A
CA
Departamento de Bioquimica, UFRGS, Porto Alegre RS, Brazil.
Siegfried
B
B
Izquierdo
I
I
D000818:Animals; D001143:Arousal / Q000502:physiology*; D008297:Male; D009619:Nociceptors / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000502:physiology; D012684:Sensory Thresholds; D012931:Social Environment