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- Title
Effects of Immobilization Stress and Hormonal Treatment on Nociception.
- Authors
Cruthirds, Danette F.; Siangco, Amanda L.; Hartman, Clinton J.; Sandefur, Danny C.; Spencer, James M.; Dyer, Christopher A.; Larco, D. Omar; Wu, T. John
- Abstract
The purpose of this study was to evaluate the effects of stress and estradiol (E2) on pain tolerance. Ovari- ectomized rats were assigned to treatment groups based on a 2 x 4 factorial design comprising stress (nonstress x stress) and hormone treatment vehicle x E2 [0.25 mg/kg/d]) x estrogen receptor alpha (ERα)- selective agonist propyl pyrazole triol (1 mg/kg/d) x estrogen receptor beta (ERß)-selective agonist diaryl- propionitrile (1 mg/kg/d). Stressed animals underwent daily 60-minute immobilization for 22 days. Pain tolerance was assessed with the hot plate test, an acute thermal pain test. In this study, stressed rats showed increased (P < .05) pain tolerance compared with nonstressed rats (25.0 ± 1.92 s vs 20.4 ± 1.02 s, respectively). Increased (P < .05) pain threshold was observed in nonstressed and stressed rats treated with E2 and the ERα agonist compared with vehicle-treated rats. Interestingly, the ERß agonist only increased (P < .10) pain thresholds in stressed rats. Stressed rats exhibited higher (P < .05) ß-endorphin levels compared with nonstressed rats in all hormone- treatment groups. With the exception of stressed rats treated with the ERß agonist, there was no hormone effect on ß-endorphin levels. These studies suggest that E2's effect on pain thresholds may be mediated via the ERα, while the interaction between chronic stress and ERß may also enhance pain threshold.
- Subjects
OVARIAN surgery; PREVENTIVE medicine; ANALYSIS of variance; ANIMAL experimentation; ENDORPHINS; ENZYME-linked immunosorbent assay; ESTRADIOL; FACTORIAL experiment designs; FISHER exact test; NOCICEPTORS; PAIN; RATS; STATISTICS; PHYSIOLOGICAL stress; T-test (Statistics); SELECTIVE estrogen receptor modulators; DATA analysis; PAIN measurement; DESCRIPTIVE statistics; THERAPEUTICS
- Publication
AANA Journal, 2011, Vol 79, Issue 5, p375
- ISSN
0094-6354
- Publication type
Article