[Effect of rutaecarpine on Alzheimer's disease-like cognitive impairments induced by high glucose in rats].

OBJECTIVE: To investigate the effects of rutaecarpine on high glucose-induced Alzheimer's disease-like pathological and cognitive dysfunction and its mechanism in rats. METHODS: Adult male SD rats were randomly divided into three groups (n=20): control group, high glucose group and rutaecarpine group. Rats in the control group were fed with conventional feed and tap water. The rats in the high glucose group were fed with conventional feed and 20% sucrose water. The rutaecarpine group was fed with fodder contain 0.01% rutaecarpine and 20% sucrose water. Morris water maze test was used to detect learning and memory and cognitive function of three groups rats after 24 weeks of feeding. Western blot analysis was used to detect tau protein at Thr205 and Ser214 sites in each group. Phosphorylation levels of GSK-3ß in serine 9 site (S9-GSK-3ß) and PP2A at cycline 307 site (Y307-PP2AC) were also detected. Immunohistochemistry further confirmed tau protein at Thr205 site in each group both in hippocampus and cortex. RESULTS: Compared with the control group, Morris water maze results showed that the latency of finding the hidden platform of the rats in high glucose group was increased significantly and the number of crossing platforms and the target quadrant residence time were significantly decreased (all P＜0.05). Immunohistochemistry showed that the phosphorylation level of tau protein at Thr205 site was significantly increased in the high glucose group compared with the control group, and the phosphorylation level of tau protein at Thr205 site in the rutaecarpine group was higher than that in the high glucose group. Western blot analysis showed that the phosphorylation level of tau protein in the high glucose group was significantly increased at Thr205 and Ser214 site compared with the control group, but the phosphorylation level of pS9-GSK-3ß was significantly decreased (all P ＜0.05). Compared with the high glucose group, the latency of finding the hidden platform of the rats in rutaecarpine group was significantly decreased, and the number of crossing platforms and the target quadrant residence time were significantly increased (both P＜0.05). Compared with the high glucose group, the phosphorylation levels of tau protein at Thr205 and Ser214 sites showed a significant decrease, but the phosphorylation level of pS9-GSK-3ß was significantly increased (all P＜0.05). CONCLUSION: Rutaecarpine can alleviate AD-like cognitive dysfunction induced by high glucose, possibly by enhancing pS9-GSK-3ß phosphorylation, down-regulating GSK-3ß activity, and thus reducing hyperphosphorylation of tau-associated sites.

[Effects of deoxygedunin on Alzheimer-like pathologic dysfunction induced by D-galactose combined with AlCl3].

OBJECTIVE: To investigate the effects of Deoxygedunin on Aß deposition, learning memory, and oxidative stress induced by D-galactose combined with AlCl3 in model rats with Alzheimer's disease and its possible mechanism. METHODS: Male SD rats were randomly divided into three groups (n=12):control group, model group (AD) and intervention group (AD+Deo). Morris water maze test was used to detect learning/memory and cognitive function in rats.Glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in homogenate of hippocampus were detected by enzyme-linked immunosorbent assay (ELISA).Tau protein expression in rat cerebral cortex was detected by immunohistochemistry.Western blot was used to detect the expressions of extracellular signal regulated kinase 1(ERK1), protein kinase B (PKB) and tropomyosin-related kinase B (TrkB) on TrkB signaling pathway. RESULTS: The results of water maze test showed that D-galactose combined with AlCl3 induced a significant increase in the escape latency compared with the control group (P<0.05).Deoxygedunin could reverse the increase of the escape latency of the model group (P<0.05).On the 7th day after removal of the platform, the model group showed an increase in escape latency compared with the control group and the intervention group (P<0.01), and the number of crossing platforms was declined (P<0.05); The results of immunohistochemistry and ELISA showed that the expressions of Aß and tau protein in the model group were increased significantly compared with those of the control group (P<0.01).The activities of SOD and GSH-Px were decreased significantly and the content of MDA was increased significantly.Compared with the model group, Deoxygedunin could reverse the increase of the expressions of Aß and tau protein (P<0.01), the decrease of SOD and GSH-Px activities (P<0.05) and the increase of the MDA content (P<0.05).Western blot results showed that Deoxygedunin treatment reversed the decreased phosphorylation levels of TrkB, AKT and ERK1 in hippocampus of the model group. CONCLUSIONS: Supplement of Deoxygedunin can significantly reverse Aß deposition, oxidative stress and cognitive deficits by activating the TrkB signal transduction pathway, which suggest that Deoxygedunin may serve as a promising therapeutic candidate for attenuating AD-like pathological dysfunction induced by D-galactose combined with AlCl3.