Both sex hormone deficiency and hypercholesterolemia are related to cognitive decline or Alzheimer's disease. However, their interactive influence on the neurodegenerative progress is not clear. This study was designed to assess the effects of ovarian hormone depletion and high cholesterol diet alone or in combination on hippocampus-related cognitive and pathological deficits in adult female ICR mice. Depletion of ovarian hormones by ovariectomy for 9 weeks resulted in significant spatial learning and memory deficits as revealed by the water maze testing. Such cognitive alteration was accompanied with increases in neuron death and decreases in choline acetyltransferase activity and synaptopysin expression in the hippocampus. On the other hand, the high cholesterol diet (3% cholesterol plus normal chow) did not exacerbate, but slightly alleviated cognitive decline and significantly attenuated hippocampal pathological changes in ovariectomized mice. Moreover, ovariectomized mice fed high cholesterol had increased serum estrogen levels compared with those fed a normal chow. These results indicate that high cholesterol intake increases the sex hormone synthesis and in turn partially attenuates hippocampus-related cognitive and pathological deficits caused by ovariectomy.
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