Effects of exercise on learning and memory, oxidative stress and nNOS expression in marginal division of striatum of ovariectomized rats

Since previous studies have shown that ovariectomy impairs memory and cognition, we investigated whether 8-week treadmill exercise would affect ovariectomy-induced memory deficits and explore the possible mechanisms of physical exercise influencing spatial learning and memory of the ovariectomized rats by detecting the rat's brain free radical metabolism and counting neural nitric oxide synthase (nNOS) expression in marginal division of the striatum (MrD). Forty female rats were assigned to one of the following groups: SHAM, SHAM+E, OVX and OVX+E group. The rats of SHAM and OVX group kept normal activities and the SHAM+E and OVX+E group rats undertook an 8-week training with progressively increasing load. Then the cognitive function was evaluated using 8-arm radial maze test. Also, oxidative stress markers in the MrD were also evaluated and the nNOS expression in MrD was detected and analyzed. Results show that ovariectomized rats were impaired in learning and memory and brain SOD (superoxide dismutase), CAT (catalase) activities were dropped and MDA (malondialdehyde) level increased via ovariectomy, nNOS expression in MrD was reduced in comparison with the SHAM group rats. While treadmill exercise significantly alleviated learning and memory decline and prevented oxidative brain damage induced by ovariectomy, nNOS expression in MrD significantly enhanced. These findings support ovariectomy can impair spatial learning and memory of the rats, the regular treadmill exercise appears to exert a protective effect against ovariectomy, induced spatial memory impairment through inhibition of oxidative stress and up-regulation MrD nNOS expression.