The difference in the female rats' responses may stem from the demands of motherhood, researchers speculate in the study "Social isolation and the inflammatory response: sex differences in the enduring effects of a prior stressor" by Gretchen L. Hermes, Anthony Montag and Martha K. McClintock of the University of Chicago, and Louis Rosenthal of the University of Wisconsin, Madison. The study appears in the February issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, published by the American Physiological Society.
The study reinforces a growing body of evidence on health disparities between men and women and may shed light on why socially isolated men are more vulnerable to disease and death than isolated women, Hermes said.
Previous studies have established a link between stress and immune function, Hermes said. But this study looked at the long-lasting effect that three months of isolation (the equivalent of chronic social stress) and one 30-minute episode of acute physical stress had on the inflammatory response, the body's innate immune response to bacteria, viruses, and parasites. The authors found that a full two to three weeks after being subjected to isolation and the acute physical stress, male rats showed a markedly slower healing response when injected with a foreign body compared to female rats, Hermes said.
This finding potentially has great clinical significance because the inflammatory response is an important immune response involved in 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.