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Objective To investigate the damage of hippocampal neurons induced by chronic cerebral ischemia in the rats,and to clarify its mechanism.Methods 90 healthy adult male SD rats were randomly divided into sham operation group (n=30 ) and experimental group (n=60 ). The chronic cerebral ischemia rat models were established by permanently ligating the common carotid arteries on both sides of the rats in experimental group.The rats in sham operation group were established by incising the cervical median,only the common carotid arteries on both sides were separated without ligating. The rats in sham operation group and experimental group were respectively sacrificed at the 7th,14th and 21st day after operation.At each time point 10 rats in sham operation group and 20 rats in experimental group were selected and sacrificed.Immunohistochemistry staining was used to observe the dynamic changes of the expression levels of choline acetyltransferase(ChAT)in hippocampus neurons, and TA-FE method was used to observe the dynamic changes of hippocampal microvascualr architecture. MiVnt image analytical system was used to quantitatively analyze the immunohistochemistry result,the microvessel density (MVD)and micorvessel area density (MVA)of horizontal part of hippocampus in the rats. Results Compared with sham operation group,the ChAT expression levels in hippocampus neurons of the rats in experimental group at different time points were significantly decreased(P<0.05);and with the prolongation of time,the ChAT expression levels were gradually decreased;the ChAT expression level in 14-day experimental group was significantly lower than that in 7-day experimental group (P<0.05 );the ChAT expression level in 21-day experimental group was significantly lower than those in 7-day and 14-day experimental groups(P<0.05).The MVD and MVA of hippocampus of the rats in experimental group at different time points were obviously decreased compared with sham operation group(P<0.05);the MVA was gradually decreased with the prolongation of time, and the MVA of hippocampus of the rats in 21-day and 14-day experimental groups were obviously decreased compared with 7-day experimental group(P<0.05);the MVD was gradually decreased with the prolongation of time,the MVD of hippocampus of the rats in 21-day and 14-day experimental groups was obviously decreased compared with 7-day experimental group(P<0.05);the MVD of hippocampus of the rats in 21-day experimental group was obviously decreased compared with 14-day experimental group(P<0.05).Conclusion Chronic cerebral ischemia can lead to the progressive decrease of the ChAT expression level,MVD and MVA of hippocampus of the rats to aggravate gradually the learning and memory dysfunction, which may be one of the reasons of vascular dementia.
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Objective To investigate the effects of sericin pretreatment on the expression of extracellular matrix(ECM) associated protein in diabetic nephropathy(DN) rats' kidney.Methods Sixty six male SD rats were randomly divided into 3 groups(n=12):normal control group,DN model group and sericine pretreatment group.DN rats model in model group and sericine pretreatment group were established by intraperitoneally injection of streptozotocin(STZ).Blood glucose≥16.7 mmol/L was taken as the standard of successful modelization.The rats in sericine pretreatment group were lavaged with sericine(2.4 g·kg~(-1)·d~(-1)) for 35 days before injecting STZ.The enzymic method was used to measure the blood glucose.Type Ⅳ collagen(cⅣ)and laminin(LN)content in the serum were detected by ELBA.The expression of transforming growth factor-β_1,(TGF-β_1)and tissue inhibitors of maprix metalloproteinase-1(TMP-1) protein in the kidney was observed by immunohistochemical staining.The expression of Smad 3 protein in the kidney was detected by Western blot.Results Compared with normal control rats,the blood glucose,cⅣ and LN content in the serum,TGF-β_1,TIMP-1 and Smad 3 expression in the kidney of the model group rats increased obviously(P<0.01).The blood glucose,cⅣ and LN content in the serum,TGF-β_1,TMP-1 and Smad3 expression in the kidney of rats in sericine pretreatment group were significantly lower than those of the rats in model group(P<0.01).Conclusion Sericin pretreatment can inhibit the activation of TGF-β/Smad 3 signal pathway in the kidney of DN rats,and prevent the decrease of MMPs activity induced by up-regulation of TIMP-1.So sericin can prevent accumulation of ECM and glomerulosclerosis during DN,and has satisfactory apotropaic effects on the development of DN.
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BACKGROUND: The metabolism of acetylcholine in hippocampus reflects the function of cholinergic nervous system whose function is associated with learning and memory as well as intelligence.OBJECTIVE: To observe the changes of choline acetyltransferase activity in rat hippocampus after ischemia-reperfusion.DESIGN: Randomized controlled trial based on rats.SETTING: A Science and Research Department of Chengde Medical College.MATERIALS:The trial was conducted in the Central Laboratory of Chengde Medical College in 2002 and the subjects were 24 clean grade Wistar rats in equal number of the two sexes(weighting 260-280 g).METHODS:The 24 rats were randomly assigned into 3 groups: ① Model group:In this group the rats were made hyperlipemia and underwent bilateral carotid arteries blocking followed by reperfusion. ② Sham operation group:In this group the rats were made hyperlipemia and underwent only exposure of bilateral carotid arteries without ischemia-reperfusion. ③ Normal control group:In this group the rats received no intervention.The brains after the rats decapitated were harvested on the 1st 7th and 15th day respectively for colorimetric determination of the choline acetyltransferase activity in hippocampus.MAIN OUTCOME MEASURES:Determination of the choline acetyltransferase activity in the groups.RESULTS:None of the 24 rats was lost in the trial. ① The choline acetyltransferase activity in the model group on the 1st and 7th day was acetyltransferase activity in the model group on the 7th day was lower than that on the 1st and 7th day was lower than that in the normal controls[(0.037±0.006) μmol/g ·s, (0.017±0.006) μmol/g·s in model group vs (0.054±0.003) μ mol/g·s,(0.058±0.006) μmol/g·s in normal control group,P ＜ 0.01].② The choline acetyltransferase activity in the model group on the 7th day was lower than that on the 1st day. With repairing of ischemia-reperfusion injury,it recovered partially[(0.039±0.007) μnmol/g.s].③ Choline acetyltrans-ferase activity in sham operation group was not different from that in normal control(P ＞ 0.05).CONCLUSION:Simple exposure of carotid arteries does not change choline acetyltransferase activity.While ischemia-reperfusion can change the choline acetyltransferase activity and cause disorders of cholinergic nervous system function,which may be the reason for rat's intellectual disorders.