Sex differences in the effects of prenatal stress on stress-induced analgesia

Prenatal stress (PS) is known to cause demasculinizing and feminizing effec ts on sexually dimorphic behavior in laboratory animals. In three separate experiments performed on the same subjects at 10 week intervals, nociceptiv e sensitivity and the analgesic response to a cold-water swim stress were a ssessed in adult male and female Swiss-Webster mice that were either stress ed prenatally or nonstressed (NS) control subjects. Experiment 1 showed ana lgesic magnitude to increase in female mice as a result of PS compared to n onstressed controls, whereas no changes were noted in male subjects. The in crease in analgesia in female mice is maintained by estrogen, as gonadectom y eliminated the increase in Experiment 2, and estrogen replacement restore d it in Experiment 3. Withdrawal latency to a noxious heat stimulus (hot-pl ate test) was also influenced by the PS manipulation; a decrease in hot-pla te latency (indicating greater nociceptive sensitivity) was noted in PS sub jects of both sexes in Experiment 1. Repeated testing (and/or age) may infl uence the effect of PS on nociceptive responses in a sex-dependent manner. The reduction in hot-plate latency was only present in males in Experiment 2, and was not present in either sex by Experiment 3. Thus, PS influences b oth baseline pain sensitivity and stress-induced analgesia responses in a s ex-and hormone-dependent fashion. (C) 1999 Elsevier Science Inc. All rights reserved.