Effect of repeated stress on novelty-induced antinociception in rats
Braz. j. med. biol. res
;
34(2): 241-244, Feb. 2001.
Article
in English
| LILACS
| ID: lil-281602
RESUMO
There is extensive evidence that acute stress induces an analgesic response in rats. On the other hand, repeatedly stressed animals may present the opposite effect, i.e., hyperalgesia. Furthermore, exposure to novelty is known to induce antinociception. The effects of repeated restraint stress on nociception after exposure to novelty, as measured by the tail-flick latency (TFL), were studied in adult male rats. The animals were stressed by restraint 1 h daily, 5 days a week for 40 days. The control group was not submitted to restraint. Nociception was assessed with a tail-flick apparatus. After being familiarized with the TFL apparatus, each group was subdivided into two other groups, i.e., with or without novelty. Animals were subjected to the TFL measurement twice. For the animals exposed to novelty, the first TFL measurement was made immediately before, and the second 2 min after a 2-min exposure to a new environment. While the control group presented an increased TFL after exposure to a novel environment, chronically stressed animals did not show this effect. These results suggest that repeated restraint stress induces an alteration in the nociceptive response, perhaps as a result of an alteration in endogenous opioids in these animals
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Stress, Psychological
/
Exploratory Behavior
/
Analgesia
Type of study:
Observational study
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2001
Type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal do Rio Grande do Sul/BR
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