Abstract |
Human research shows that childhood traumas are associated with an increased risk for mood and anxiety disorders. On the other hand, there is evidence that exercise helps to prevent and to ameliorate anxiety and depression. Likewise, in rats, maternal separation (MS) during early postnatal period, functions as a stressor and has been associated with emotional and social deficits in adulthood. Although several studies have shown that environmental enrichment overcomes behavioral deficits and depressive-like behavior induced by stress, the specific role of physical exercise, commonly used as enrichment stimulus in such studies, is not fully understood. In the present study we tested the effects of MS on emotional and social aspects of behavior in adulthood, combined with the examination of potential reversibility of such deficits by chronic wheel-running (WR). Male Sprague Dawley rats were divided in eight groups: MS - free access to WR-individually housed, MS-free access to WR-grouped housed, MS - no access to WR- individually housed, MS- no access to WR- grouped housed, nonMS - free access to WR- individually housed, nonMS- free access to WR- grouped housed, non MS- no access to WR- individually housed, nonMS - no access to WR- grouped housed. Anxiety-like behavior, depressive-like behavior, social behavior and social memory were tested using the elevated plus maze (EPM), thigmotaxis, forced-swim test (FST), sucrose preference, social interaction (SI) and social recognition (SR) tasks. MS rats showed increased anxiety- and depressive-like behaviors in adulthood. WR increased the time spent in the open arms and the exploratory behavior in the EPM (rearing, SAPs and head dips), decreased the time spent in the outer zone and the corners of the open field, while it decreased the immobility and increased the climbing in FST, showing anxiolytic and antidepressant actions. Moreover, MS and social isolation lead to social behavior and recognition deficits in adulthood. WR reversed those effects by decreasing social avoidance and increasing the contact behavior and exploration, while significantly improving social discrimination. These results suggest that WR overcomes early life stress-induced emotional and social impairments and provide further support to the hypothesis that exercise may be used as an adjunct to treatment of anxiety and mood disorders.
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