Protective effects and mechanism of total coptis alkaloids on a beta 25-35 induced learning and memory dysfunction in rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To observe the effect of total coptis alkaloids (TCA) on beta -amyloid peptide (A beta 25-35) induced learning and memory dysfunction in rats, and to explore its mechanism.</p><p><b>METHODS</b>Forty male Wistar rats were randomly divided into four groups: the control group, the model group, the TCA low dose (60 mg/kg) group and the TCA high dose (120 mg/kg) group, 10 in each. A beta 25-35 (5microl, 2 microg/microl) was injected into bilateral hippocampi of each rat to induce learning and memory dysfunction. TCA were administered through intragavage for consecutive 15 days. Morris Water Maze test was used to assess the impairment of learning and memory; concentration of malondialdehyde (MDA) in cerebral cortex was determined by thiobarbituric acid reactive substance to indicate the level of lipid peroxidation in brain tissues; activity of manganese-superoxide dismutase (Mn-SOD) in cerebral cortex was determined by xanthine-oxidase to indicate the activity of the enzyme; and NF- kappa B protein expression in cerebral cortex was measured by SP immunohistochemistry.</p><p><b>RESULTS</b>(1) Morris Water Maze test showed that, during the 4 consecutive days of acquisition trials, the rats in the model group took longer latency and searching distance than those in the control group (P<0.01), which could be shortened by high dose TCA (P<0.05); during the spatial probe trial on the fifth day, the rats in the model group took shorter searching time and distance on the previous flat area than those in the control group (P<0.01), which could be prolonged after TCA treatment (for low dose group, P<0.05; for high dose group, P<0.01). (2) Analysis of cerebral cortical tissues showed that, compared with the control group, MDA level got significantly increased and Mn-SOD activity decreased in the model group (both P<0.01). After having been treated with TCA, the MDA level got significantly decreased (P<0.05 and P<0.01 respectively for low and high dose group), while relative increase of Mn-SOD activity only appeared in high dose group (P<0.05). (3) Immunohistochemistry analysis showed the protein expression of NF- kappa B got significantly increased after modeling, while high dose TCA can significantly inhibit it.</p><p><b>CONCLUSION</b>TCA could improve A beta 25-35 induced dysfunction of learning and memory in rats, and its protective mechanism is associated with its actions in decreasing MDA level, increasing Mn-SOD activity and inhibiting the expression of NF-kappa B in cerebral cortex.</p>

Protective effect of ecdysterone on PC12 cells cytotoxicity induced by beta-amyloid25-35 / 中国结合医学杂志

<p><b>OBJECTIVE</b>To examine the protective effect of ecdysterone (ECR) against beta-amyloid peptide fragment(25-35) (Abeta(25-35))-induced PC12 cells cytotoxicity, and to further explore its mechanism.</p><p><b>METHODS</b>Experimental PC12 cells were divided into the Abeta group (treated by Abeta(25-35) 100 micromol/L), the blank group (untreated), the positive control group (treated by Vit E 100 micromol/L after induction) and the ECR treated groups (treated by ECR with different concentrations of 1, 50 and 100 micromol/L). The damaged and survival condition of PC12 cells in various groups was monitored by lactate dehydrogenase (LDH) release and MTT assay. The content of malondialdehyde (MDA) was measured by fluorometric assay to indicate the lipid peroxidation. And the antioxidant enzymes activities in PC12 cells, including superoxide dismutases (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), were detected respectively.</p><p><b>RESULTS</b>After PC12 cells were treated with Abeta(25-35) (100 micromol/L) for 24 hrs, they revealed a great decrease in MTT absorbance and activity of antioxidant enzymes, including SOD, CAT and GSH-Px as well as a significant increase of LDH activity and MDA content in PC12 cells (P < 0.01). When the cells was pretreated with 1-100 micromol/L ECR for 24 hrs before Abeta(25-35) treatment, the above-mentioned cytotoxic effect of Abeta(25-35) could be significantly attenuated dose-dependently, for ECR 50 micromol/L, P < 0.05 and for ECR 100 micromol/L, P < 0.01. Moreover, ECR also showed significant inhibition on the Abeta(25-35) induced decrease of SOD and GSH-Px activity, but not on that of CAT.</p><p><b>CONCLUSION</b>ECR could protect PC12 cells from cytotoxicity of Abeta(25-35), and the protective mechanism might be related to the increase of SOD and GSH-Px activities and the decrease of MDA resulting from the ECR-pretreatment.</p>

Effect of ecdysterone on the expression of c-fos in the brain of rats induced by microinjection beta-AP25-35 into the hippocampus / 药学学报

<p><b>AIM</b>To observe the behavior in learning and memory and the expression of c-fos gene from the brain of rats induced by beta-AP25-35, and the intervention of ecdysterone, in order to explore the protective mechanism of ecdysterone on the dysfunction of learning and memory of the rat induced by beta-AP25-35.</p><p><b>METHODS</b>Microinjection of beta-AP25-35 into hippocampus induced learning and memory dysfunction of rats. The learning and memory of rats were observed by Morris Water Maze. The expression of c-fos gene in the brain was detected by immunohistochemistry.</p><p><b>RESULTS</b>The results of Morris Water Maze showed that after rats were microinjected beta-AP25-35 into hippocampus, the rats in model group took longer latency and searching distance compared with the ones in control group (P < 0.01), and the rats in treated group (ECR 4 mg x kg(-1), ECR 8 mg x kg(-1) and nimodipine 7.2 mg x kg(-1)) took shorter latency and searching distance, especially the ECR 8 mg kg(-1) group (P < 0.01). At the same time, after the 5 days training, there was a higher expression of c-fos in hippocampus and cortex from the rats in control group than that in model group (P < 0.01), but in the treated group, there was a relatively higher expression of c-fos, especially the ECR 8 mg x kg(-1) group (P < 0.01).</p><p><b>CONCLUSION</b>Microinjection of beta-AP25-35 into the rat hippocampus resulted in dysfunction of learning and memory. Ecdysterone was shown to improve the learning and memory of the rats and increase the expression of c-fos. Increasing the expression of c-fos is probably one of the most molecular mechanism of its protection.</p>

The effects of genistein on epidermal growth factor receptor mediated signal transduction pathway in human ovarian carcinoma cells lines SKOV3 and its xenograft in nude mice / 中华病理学杂志

<p><b>OBJECTIVE</b>It was reported previously that genistein could inhibit proliferation of human ovarian carcinoma cell line SKOV(3), but mechanism was not clear. There is a close relationship between EGFR mediated signal transduction pathway and the development of ovarian tumor. This study aimed to investigate the effects of genistein on the EGFR mediated signal transduction pathway and to clarify its mechanisms of proliferation inhibition on human ovarian carcinoma cell line SKOV(3) and its xenograft in nude mice.</p><p><b>METHODS</b>The expression of c-erbB-2 protein was determined using immunocytochemistry. The expressions of c-jun and c-fos protein were determined using Western blotting. The expression of c-erbB-2, c-raf-1, c-jun and c-fos mRNA were tested by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>The expression of c-erbB-2, c-raf-1 and its downstream gene c-jun and c-fos were decreased at mRNA level in the 20 micromol/L genistein group. The expression of c-erbB-2 protein were decreased, its average absorbency (A) were decreased after treatment of SKOV(3) with 20 micromol/L genistein for 48 h, reached at 0.42 +/- 0.02 (P < 0.05). Western blotting demonstrated that the expressions of c-jun and c-fos protein were decreased gradually after being treated with 20 micromol/L genistein for 12 - 72 h.</p><p><b>CONCLUSIONS</b>Genistein could down-regulate the expression of two key genes, c-erbB-2 and c-raf-1 at mRNA and protein level in the EGFR mediated signal transduction pathway, and down-regulate the expression of its downstream nuclear transcription factors c-jun and c-fos at mRNA and protein level. It is suggested that interfering the expressions of some key signal molecules in EGFR mediated signal transduction system by genistein may account for its molecular foundation of proliferation inhibition in ovarian carcinoma.</p>