Effects of genistein and 17ª²¦Âestradiol on the spatial learning and memory in ovariecomized rats

    HUANG Yanª²Hong, XIN Xiaoª²Yan, CHEN Yaª²Qiong, ZHANG Qingª²Hong, XIONG Xiaoª²Yun, WANG Siª²Wang

    1Department of Obstetrics and Gynecology, Xijing Hospital, 2Department of Physiology, 3Department of Pharmacology, School of Basic Medicine, 4Institute of Meteria Medical, Fourth Military Medical University, Xi¡¯an 710033, China

    ¡¾Abstract¡¿ AIM: To investigate the effects of genistein (GST) and 17ª²¦Âestradiol (E2) on the spatial learning and memory in ovariectomized rats and their mechanism of action. METHODS: Forty adult Spragueª²Dawley female rats were randomly divided into 5 groups: the Sham ª²ovariectomized (Sham), the ovariectomized (OVX), the E2, the GST higher dosager (GSTª²h) and the GST lower dosage (GSTª²L). Using Morris water maze, the change in spatial learning and memory function and the effects of GST and E2 were observed in the ovariectomized rats, acetylcholinesterase (Ache) activity was assayed spectrophotometrically in respective brain areas: Frontal cortex and hippocampus, and the effects of GST and E2 on Ache activity were examined. RESULTS: Sever weeks after ovariectomy(OVX) resulted in the decrease in learning and memory in female rats. The escape latency of the OVX group was significantly increased compared with that in the Sham group (88.9¡À35.1) s vs (51.7¡À36.9) s, P<0.05, and the frequency of memory in the OVX group was significantly decreased (18.7¡À2.7) vs (24.9¡À4.5), P<0.05. A significant increase in AchE activity was found in frontal cortex and hippocampus in the OVX group in comparison with their respective regions of the Sham group (286.7¡À27.8) ¦Ìkat/L vs (245.6¡À36.1) ¦Ìkat/L, (363.9¡À46.1) ¦Ìkat/L vs (275.8¡À52.8) ¦Ìkat/L, P<0.05, P<0.01. Replacement therapy for 6 weeks, the E2 group showed a significant change in the escape latency and the frequency of memory as compared with the OVX group (57.3¡À21.7) s vs (88.9¡À35.1) s, (25.5¡À5.4) vs (18.7¡À2.7), P<0.05, P<0.01. The frequency of memory in the GSTª²L group was significantly decreased compared with that in the OVX group (22.7¡À2.0) vs (18.7¡À2.7), P<0.05. The GST (higher and lower dosager) group and E2 group showed a significant change in AchE activity as compared with the OVX group, and the AchE activity was significantly dereased in the in frontal cortex and hippocampus (P<0.01). The GST and E2 significantly inhibited the decrease of spatial learning and memory and the increase of Ache activity in frontal cortex and hippocampus induced by OVX. CONCLUSION: The GST and E2 significantly inhibited the decrease of spatial learning and memory due to OVX, which may correlate with the decrease of acetylcholine¡¯s activity in the brain. ......