| Objective:The current study was preformed to investigate the effects of procyani- dins, a polyphenol extracted from grape seeds, on learning and memory in vascular de- m-entia(VD) model rats and the possible mechanisms involved; the effect of procyanidins on the viability and morphology of cell was also investigated by establishing the oxygen-glucose deprivation (OGD) model in PC12 cells.Methods:In vivo, we used two different methods to establish VD model in rats, by which we investigated the effects of procyanidins on learning and memory and the possible mechanisms involved.(1) The experimental model of VD in rats was established by transient(2h) middle cerebral artery occlusion(MCAO).50 rats were randomly divided into five equal groups:sham operation group, model group, positive control group(Ginkgo leaf extract,24mg/kg), low dose GSP group(50mg/kg) and high dose GSP group(150mg/kg).The ability of learning and memory in VD rats was measured by Morris water maze tset(Day21-26) and step-down avoidance test(Day27-28). On day29 the rats were sacarificed by chloral hydrate after all the behavior tests were completed.5ml blood were drawed from the heart of each rat to produce serum, we used TNF-αand IL-1βELISA kits to test the inflammation of the periphery system of VD rats. The contents of malondialdehyde(MDA), total antioxidant capacity(T-AOC), the activities of superoxidedismutase(SOD) and cholinesterase (ChE) in the ischemic hemisphere were also measured.(2) We used a modified Pulsinelli's 4-vessel occlusion (4-VO) method for replicating vascular dementia in rats.50 male Wistar rats were equally divided into 5 experimental groups:in one the rats were subject to sham-operated, and in the other four the rats were subjected to the 4-VO surgery followed by oral administration of vehicle, Ginkgo leaf extract(24 mg/kg/day), procyanidins(50 or 150mg/kg/day) respectively.The spatial learning and memory performance was recorded as the acquisition trial and probe trial in the Morris water maze from day15 to day20. The passive avoidance test was conducted on day21 and day22.After completing all the behavioral tests, animals were sacrificed by chloral hydrate and hippocampi and cortex dissected. The levels of malondialdehyde(MDA), glutathione(GSH), total antioxidant capacity(T-AOC) and the activity of superoxidedismutase(SOD) in the brain tissue were determined by colorimetric Assay Kit. The gene expression of bax and bcl-2 in the rat hippocampus was detected by real-time PCR. TNF-αand IL-1βin the hippocampus were detected by western bloting. Pathohistology changes in the VD rat hippocampus CA1 district were observed by Nissl's staining through micro-morphological examination.(3) By establishing oxygen-glucose deprivation (OGD) model of PC12 cells in vitro, we observed the changes of viability and morphology of the cell with GSP and edaravone. At the same time, MTT assay was applied to evaluate the viability of the cell and biochemical method was used to determine LDH activity, the contents of the malondialdehyde(MDA), the activity of superoxide dismutase(SOD).Results:(1) In MCAO model rats:Compared with sham operated group, VD rats spent a longer time in finding the hidden platform during the acquisition trials of the Morris water maze task, this was reversed by repeated treatment with GSP. GSP also reversed memory deficits, as evidenced by increased passing times of the platform in the probe trial. In the passive avoidance test, VD rats showed decreased retention tested 24 h after initial training; this was reversed by GSP. GSP also decreased the frequency of errors in step-down avoidance test. Compared with VD rats, GSP increased the activity of SOD and T-AOC, decreased the content of MDA, while the activity of ChE of each group showed no difference. The concentration of serum inflammatory factor TNF-αand IL-1βincreased significantly in VD rats and was reduced by GSP.(2) In modified Pulsinelli's 4-vessel occlusion model:The vascular dementia rats treated with procyanidins showed decreased escaped latency during acquisition training, procyanidins also increased exploration time in the target quadrant and frequency of crossing the platform during probe trial. In the passive avoidance test, VD rats showed decreased retention 24 h after initial training; this was reversed by GSP.The administration of procyanidins induced increase in GSH, T-AOC contents and SOD activity with lowering MDA levels in the brain. Procyanidins upregulated the bcl-2/bax mRNA expression ratio of the VD rat hippocampus. The expression of TNF-αand IL-1βin the VD rat hippocampus were upregulated and the procyanidins significantly reduced the release of these inflammation-related factors. In the sham group, the neurons neatly arranged and the number of nissl body in neurons was large. While in VD rats, the conformations of neurons were indistinct, and the nissl body in the cell body and dendritic was dissolved. After treated with procyanidins, the neurons neatly arranged and there were more nissl body in neurons comparing to the VD rats.(3) In the cell test, the cellular morphology of PC 12 cells were altered after OGD. GSP could significantly decrease the injury of PC 12 by OGD. Compared with the model group, the MTT value of GSP treated group increased obviously, LDH leakage of GSP treated group decreased obviously. Meanwhile, GSP increased the level of SOD in cell supernatant, while decreased the content of MDA.Conclusion:These findings suggest that Procyanidins have potentials for improving the spatial cognition with VD, which is possibly due to the antioxidative, anti-apoptotic, anti-inflammation effects of polyphenol. |
PDF Full Text Request