Combined exercise ameliorates ovariectomy-induced cognitive impairment by enhancing cell proliferation and suppressing apoptosis.

OBJECTIVE: Estrogen plays an important role in cognitive function, including attention, learning, and memory, and affects the structure and function of brain areas. We investigated the effects of combined exercise on memory deficits induced by ovariectomy (OVX) in relation to cell proliferation and apoptosis in the hippocampus.
METHODS: Rats were randomly divided into four groups: sham, sham and exercise, OVX, and OVX and exercise. Rats in combined exercise groups were subjected to 3 days of resistance training and 3 days of running (for a total of 6 d/wk) for eight consecutive weeks. Rats were tested in step-down avoidance task and Morris water maze task to verify the effects of OVX on short-term and spatial working memory.
RESULTS: In the present study, the number of BrdU-positive and doublecortin-positive cells and expression of brain-derived neurotrophic factor, TrkB, and Bcl-2 decreased; expression of Bax and the number of caspase-3-positive and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells increased; and short-term and spatial working memory decreased in the OVX group compared with the sham group. Conversely, when the combined exercise group was compared with the OVX group, the number of BrdU-positive and doublecortin-positive cells and expression of brain-derived neurotrophic factor, TrkB, and Bcl-2 increased; expression of Bax and the number of caspase-3-positive and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells decreased; and short-term and spatial working memory increased.
CONCLUSIONS: Combined exercise increases cell proliferation and inhibits apoptosis in the hippocampus and improves cognitive function despite estrogen deficiency.