The Study On Caspases Expression In The Temporoparietal Cortex And Hippocampus In The Rat Model Of Lymphostatic Encephalopathy

Objectives:To observe several caspases expression in the temporoparietal cortex and hippocampus in the rat model of lymphostatic encephalopathy and the relationship between them, then try to further discover the molecular mechanisms of apoptosis.Methods:176 male adult Wistar rats were randomly divided into operation group,sham-operation group and control. We use operation group to establish the model of lymphostatic encephalopathy according to Casley-Smith. The lymph nodes and lymphatics in the sham-operation group were only separated and exposed. Semi-quantitive RT-PCR method was used to explore the expression of caspases mRNA. Immunohistochemistry technique was used to observe Caspase-3 expression. TUNEL staining was used to detect the neuronal apoptosis of temporoparietal cortex and hippocampus.Results:(1) The animals of the operation group are all in low spirits and appear to be apathy and drowsiness. Spontaneous motor activities decrease. There is no significantly change between sham operation group and control group.(2) TUNEL staining shows an occurrence of neuronal apoptosis in temporoparietal cortex and hippocampus. In temporoparietal cortex, there showed a peak at 5 days after operation. However, in the hippocampus, it showed a highest level at 3 days after operation. Compared with sham-operation group and control group, there showed a significantly difference (p<0.05).(3) From the immunohistochemistry we could see the expression of Caspase-3 in cortex and hippocampus. The highest expression occurred at 3 days after operation. Compared with sham-operation group and control group, there also showed a significantly difference (p<0.05).(4) RT-PCR:1) Caspase-3 mRNA:Caspase-3 mRNA was up-regulated in temporoparietal cortex and hippocampus within 3 days, the highest expression occurred in the first day after operation and more prominent in the hippocampus.2) Caspase-9 mRNA:Compared with sham-operation group and control group, the expression of caspase-9 mRNA did not change in temporoparietal cortex and hippocampus, there was no statistical difference among three groups (p>0.05).3) Caspase-11 mRNA:In temporoparietal cortex, there is no statistical difference between groups. In hippocampus, Caspase-11 mRNA expression is up-regulated at 3-5 days after operation, the highest expression occurred at 3 days after operation. Then it reached the normal level after 5 days.4) Caspase-12 mRNA:In temporoparietal cortex, Caspase-12 mRNA expression rose at 1 day and reached the highest level at 3 days after operation. Then it began to decline. But it showed a significantly difference compared with sham group and control. In hippocampus, we could see a higher expression of Caspase-12 mRNA from 1 to 3 days after operation. The highest occurred at the first day after operation.Conclusions:In the rat model of lymphostatic encephalopathy, neuronal apoptosis occurred in temporoparietal cortex and hippocampus. Neuronal apoptosis is probably related to the activation of Caspase-3. Caspase-11,12 may play an important role in the process of apoptosis.