GENDER, COPYING, SYMPTOMS AND THERAPIES
SEX DIFFERENCES AND PAIN
Although differences in pain sensitivity between women and men are partly attributable to social conditioning and to psychosocial factors, many laboratory studies of humans have described sex differences in sensitivity to noxious stimuli, suggesting that biological mechanisms underlie such differences. In addition, sex hormones influence pain sensitivity; pain threshold and pain tolerance in women vary with the stage of the menstrual cycle. Imaging studies of the brain have shown differences between men and women in the spatial pattern and intensity of response to acute pain. Among rodents, females are more sensitive than males to noxious stimuli and have lower levels of stress-induced analgesia. Male rodents generally have stronger analgesic response to μ-opioid receptor agonists than females. Research on transgenic mice suggests that normal males have a higher level of activity in the endogenous analgesic system compared with normal females, and a human study has found that μ-receptors in the healthy female brain are activated differently from those in the healthy male brain. The response to κ-opioids, which is mediated by the melanocortin-1 receptor gene in both mice and humans, is also different for each sex.
Although differences in pain sensitivity between women and men are partly attributable to social conditioning and to psychosocial factors, many laboratory studies of humans have described sex differences in sensitivity to noxious stimuli, suggesting that biological mechanisms underlie such differences. In addition, sex hormones influence pain sensitivity; pain threshold and pain tolerance in women vary with the stage of the menstrual cycle. Imaging studies of the brain have shown differences between men and women in the spatial pattern and intensity of response to acute pain. Among rodents, females are more sensitive than males to noxious stimuli and have lower levels of stress-induced analgesia. Male rodents generally have stronger analgesic response to μ-opioid receptor agonists than females. Research on transgenic mice suggests that normal males have a higher level of activity in the endogenous analgesic system compared with normal females, and a human study has found that μ-receptors in the healthy female brain are activated differently from those in the healthy male brain. The response to κ-opioids, which is mediated by the melanocortin-1 receptor gene in both mice and humans, is also different for each sex.