Na+, K+ ATPase activity is reduced in amygdala of rats with chronic stress-induced anxiety-like behavior.

In this study, we examined the effects of two chronic stress regimens upon anxiety-like behavior, Na(+), K(+)-ATPase activity and immunocontent, and oxidative stress parameters (antioxidant enzymes and reactive oxygen species production) in the amygdala. Male rats were subjected to chronic unpredictable and to chronic restraint stress for 40 days. Subsequently, anxiety-like behavior was examined. Both stressed groups presented increased anxiety-like behavior. Reduced amygdalal Na(+), K(+)-ATPase activity in the synaptic plasma membranes was also observed, without alterations in the amygdala immunocontent. In addition, when analyzing oxidative stress parameters, only superoxide dismutase activity was decreased in the amygdala of animals subjected to unpredictable stress. We conclude that both models of chronic stress lead to anxiety-like behavior and decreased amygdalal Na(+), K(+)-ATPase activity, which appears not to be related to oxidative imbalance. The relationship between this decreased activity and anxiety-like behavior remains to be studied.