Effects of immobilization stress and hormonal treatment on nociception.

The purpose of this study was to evaluate the effects of stress and estradiol (E2) on pain tolerance. Ovariectomized 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 (ERalpha)-selective agonist propyl pyrazole triol (1 mg/kg/d) x estrogen receptor beta (ERbeta)-selective agonist diarylpropionitrile (1 mg/kg/d).