Effect of one or more footshocks on spleen and blood lymphocyte proliferation in rats

The effect of 1 (1.6 mA, 5 s), 3, 8, or 16 inescapable footshocks on the response of spleen and peripheral blood lymphocytes to nonspecific mitogenic stimulation and plasma corticosterone levels was studied in adult Lewis male rats. One footshock suppressed mitogenic activity in the spleen and this effect was comparable to 3, 8, and 16 footshocks. The maximum suppression to nonspecific mitogenic stimulation in the spleen was observed at 1 and 10 min after exposure to a single footshock and suppression of the mitogenic responses in the spleen persisted for at least 60 min. In contrast, immediately after a single footshock peripheral blood lymphocyte mitogenic function was not suppressed but instead was significantly enhanced. A significant suppression of mitogenic responsiveness of blood lymphocytes occurred 30 min after exposure to a single footshock and at 60 min the blood mitogenic activity did not differ from the home cage controls. Eight footshocks produced a significant suppression of mitogenic responses in the blood and 16 footshocks produced the greatest suppression of blood mitogenic function. These data suggest that 1 brief footshock caused activation of the HPA axis and sympathetic nervous system and resulted in significant alteration of the immune system. We suggest that noncomplex models of short-term stress may provide for a better understanding of the mechanisms underlying the development of stress reactions in the CNS and the periphery.