[Effect of puerarin on the expression of NMDA receptor in the hippocampus CA1 region after focal cerebral ischemia in rats].

OBJECTIVE: To study the antagonistic action of Puerarin against the excitatory amino acid toxicity, and to further explore its brain protection mechanisms. METHODS: Focal cerebral ischemia model was set up with middle cerebral artery occlusion by intraluminal block in this study. After cerebral ischemia, Puerarin was administered at different time point. The volume of cerebral ischemia was assessed by TTC stain. NR1 positive neurons in hippocampus CA1 region was determined by immunohistochemistry SABC method. RESULTS: The cerebral ischemia volumes were smaller in 2 h and 12 h model treatment groups (P < 0.05) than those in model control groups, but no significant differences were observed in 24 h model treatment group. Compared with sham-operation group, the NR1-positive cells in hippocampal CA1 region were increased obviously (P < 0.05) in both model control and model treatment groups. Compared with model control groups, the NR1-positive cells in hippocampal CA1 were decreased obviously (P < 0.05) in 2 h and 12 h treatment groups. CONCLUSION: The treatment of Puerarin within 12 h after ischemia can cut down the expression of NMDA receptor. This indicates that the puerarin treatment in earlier period after ischemia can indirectly rivalry toxic effect of excitatory amino acids, relieve neural injury.

[Protective effect of puerarin against calcium overload after focal cerebral ischemia injury in rats].

OBJECTIVE: To observe the temporal and spatial changes in the distribution of Ca2+ in the rat brain following focal cerebral ischemia injury and explore the protective effect of puerarin against calcium overload. METHODS: Focal cerebral ischemia was induced by middle cerebral artery occlusion in rats. After cerebral ischemia, puerarin was administered in the rats at different time points. The volume of ischemic cerebral tissue was assessed by TTC staining, and the fluorescence intensity of Ca2+ in the cortex and corpora striata was determined under laser scanning confocal microscope. RESULTS: The fluorescence intensity of Ca2+ in the infracted cortex and corpora striata begun to increase 2 h after the ischemia and was further enhanced with the prolongation of the ischemic time. No significance was found in the fluorescence intensity of Ca2+ between the cortex and corpora striata. The fluorescence intensity of Ca2+ in the infarcted corpora striata was obviously higher than that in the cortex after ischemia. Compared with that in the ischemic model group, the fluorescence intensity of Ca2+ in the infarcted cortex and corpora striata decreased significantly at 2 and 12 h following puerarin intervention (P<0.05). CONCLUSION: Puerarin treatment can relieve calcium overload, reduce cerebral ischemic volume and play a neuroprotective role against focal cerebral ischemia. Twelve hours following cerebral ischemic injury may be the time window for administering puerarin intervention.

Protective effects and mechanism of puerarin on learning-memory disorder after global cerebral ischemia-reperfusion injury in rats.

OBJECTIVE: To observe the effect of puerarin on the learning-memory disorder after global cerebral ischemia-reperfusion injury in rats, and to explore its mechanism of action. METHODS: The global cerebral ischemia-reperfusion injury model was established using the modifified Pulsinelli four-vessel occlusion in Sprague-Dawley rats. Rats were intraperitoneally injected with puerarin (100 mg/kg) 1 h before ischemia and once every 6 h afterwards. The learning-memory ability was evaluated by the passive avoidance test. The dynamic changes of the cell counts of apoptosis and positive expression of Bcl-2 in the hippocampus CA1 region were determined by the TUNEL and immunohistochemical methods, respectively. RESULTS: (1) Compared with the reperfusion group, the step through latency (STL) in the passive avoidance test in the puerarin group was prolonged signifificantly (P<0.01). (2) The apoptotic neurons were injured most severely on the 3rd day in the hippocampal CA1 region after global ischemia and reperfusion. In the puerarin group, the number of apoptotic cells decreased at respective time points after ischemia-reperfusion (P<0.01). (3) The level of positive expression of Bcl-2 varied according to the duration of reperfusion and the peak level occurred on day 1 in the hippocampal CA1 region after global cerebral ischemia. Compared with the reperfusion group, the expression of Bcl-2 in the puerarin group was up-regulated at the respective time points after ischemia reperfusion (P<0.01), reaching the peak on day 1. CONCLUSIONS: Puerarin could improve the learning-memory ability after global cerebral ischemia and reperfusion in rats. The protective mechanism might be related to the effect of inhibiting or delaying the cell apoptosis through up-regulating the expression of Bcl-2 after ischemia and reperfusion.

[Hypoxia inducible factor-1alpha expression trends in hippocampus of rat of different ages].

OBJECTIVE: To reveal the expression trends of HIF-1alpha in hippocampus of different age rats, investigate the role of HIF-1alpha in the aging process of nervous system. METHODS: The cerebral tissues was collectd from rats of different age, including 3, 18, 24, 36 months old. There were 6 rats in each age group. The expressions of nissl body and HIF-1alpha in different part of hippocampus were observed by nissl staining and immunohistochemical technique. RESULTS: (1) With the increase of rat age, nerve cells appeared to be bigger and to arrange sparsely, while the nissl body decreased; (2) The positive HIF-1alpha staining cells in CA1, CA3 region of hippocampus increased along with the increase of rat age. The difference between any two age groups showed statistical significance (P < 0.05). CONCLUSION: The function of protein synthesis weakened in nerve cells but the expression of HIF-1alpha increased with the age increasing, which may play an important role in aging of nervous system.