Abstract
The effects of restraint stress on immune function were studied using diet-induced obese mice. C57BL/6J female mice 4 weeks of age were fed for 9 weeks on a control diet (control group) or a high-fat diet (obese group). Mice in each group were further divided into two groups: a stress (+) group that was subjected to restraint stress for 12h, and a stress (-) group that was subjected to only fasting. Mice in these four groups received intraperitoneal immunization with ovalbumin (OVA) immediately after restraint or fasting. The serum leptin concentration in the obese group was high, and was further increased by restraint stress. In both diet groups, the number of splenocytes and the lymphocytic proliferative response to LPS stimulation were decreased by stress loading. On the other hand, both IL-2 and IL-4 production in response to OVA stimulation were increased by restraint stress. A high-fat diet decreased the OVA-specific antibody titer and the value was lowest in the obese-stress (+) group. Thus, an antigen-specific immunoreaction can be changed by stress loading. Moreover, it is possible that leptin may have an influence on immune function in obese individuals subjected to stress.
