The study is an eye-opener to the upcoming proof that there exist health differences in men and women and perhaps holds a clue to the reason why socially isolated men are prone to disease, as compared to isolated women.
Previous studies have shown a connection between stress and immune function. But this study observed the effects of chronic stress from three months of isolation (the equivalent of chronic social stress) with a single 30-minute episode of severe physical stress. This was tested on male and female rats. The effect on the inflammatory response was gauged, and the authors found that upon two to three weeks of isolation and one instance of acute physical stress, male rats showed a significantly slower healing pattern, when injected with a foreign body as compared to female rats.
This finding is extremely important because the inflammatory response is nothing but the immune response which is crucial for the healing of many diseases, including heart disease, cancer, and infectious disease, said senior author Martha McClintock, director of the Institute for Mind and Biology at the University of Chicago.
It is still unclear as to the reason for faster healing in females under stress rather than in male under stress, but the authors said it may be a protection that evolved in the context of females protecting their offspring.
To quote the paper," While lactating, maternal rats become highly aggressive toward intruders and predators and are at high risk for wounding, particularly from neck bites that puncture the skin where the foreign substance was induced , Stress-induced facilitation of the inflammatory response in threatened maternal rats would promote their healing and survival, with obvious benefit to her dependent offspring."
Females may have a different physiological response to stress that evolved differently from males because of motherhood. According to the authors," oxytocin, a hormone secreted by females in social contexts, may function as part of an alternative stress regulatory system that facilitates wound healing."
The alteration in the response of female rats' could have risen from the demands of motherhood, researchers seem to say in the study titled "Social isolation and the inflammatory response: sex differences in the enduring effects of a prior stressor". This study has been carried out by Gretchen L. Hermes, Anthony Montag and Martha K. McClintock of the University of Chicago, and Louis Rosenthal of the University of Wisconsin, Madison and is published in the February issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology