COLD SWIM STRESS LEADS TO ENHANCED SPLENOCYTE RESPONSIVENESS TO CONCANAVALIN-A, DECREASED SERUM TESTOSTERONE, AND INCREASED SERUM CORTICOSTERONE, GLUCOSE, AND PROTEIN

This study extends previous observations of the conditions under which enhancement of lymphocyte activity occurs following cold swim stress and presents a possible explanation for the enhancement observed. Eigh t- to twelve-week old male Sprague-Dawley rats swam for 10 minutes dai ly for one, three, or five days in cold water at 15 degrees C and were killed 0, 30, or 240 minutes following the last swim. Apparatus contr ol animals were placed into an empty swim tank for 10 minutes and then returned to their home cages. Home cage control animals were not mani pulated experimentally at all. Splenocyte but not thymocyte responses to concanavalin A were significantly enhanced after one, three, and fi ve days of stress. This enhancement was seen after 0, 30, and 240 minu tes of recovery and also in the apparatus controls! The number of sple nocytes did not change significantly, but thymocyte number declined fo llowing the swims. The blood displayed no changes in leukocyte percent s. Serum corticosterone levels were significantly higher and serum tes tosterone levels were significantly lower after one, three, and five d ays of stress. The drop in testosterone levels may have released the l ymphocytes from inhibition by this hormone, resulting in increased res ponsiveness. There were significant elevations in levels of blood gluc ose and protein following one, three, and five days of stress sessions , correlated with the increases in serum corticosterone.