| ObjectiveMany disease can lead to the cerebral ischemia, and the vulnerable hippocampus is often treated as the important cerebral ischemia model. Transient cerebral ischemia may result in degeneration, necrosis, delayed neuron death ( DND) and/or apoptosis. The major biological effect of Calcitonin Gene Related Peptide(CGRP) is to relax the cerebral vascular and protect the mature neuron. Nerve Growth Factor(NGF) may maintain alive of the mature neuron and participate the repair of injured neuron. Protein Kinase C ( PKC ) depending upon phospholipid and Ca + , plays an important role in the apoptosis. Extracellular signal regulated kinase(Erk) , a member of MAPK family, could stimulate cell proliferation and restrain cell apoptosis by activating Ras - Raf - Mek - Erk signal cascade pathway. In the present study, an novel model of whole cerebral is-chemia/reperfusion was established, and the methods of histopathology,immuno-histochemistry and in situ hybridization (ISH) were applied to study the neuron apoptosis in brain tissue during ischemia /reperfusion , the expression of Erk, PKC.ErkmRNA and the effects of NGF and CGRP on them.MethodspThirty male Wistar rats weighting 300 - 350g supplied by experimental animal center of China Medical University were divided randomly in sham group , is-chemia/reperfusion(I/R) group , CGRP group , NGF group and CGRP plus NGF (C&N) group. An novel model of whole cerebral ischemia/reperfusion was es-tablished. Observe ischemic changes in cerebral tissue by LM before and after the experiment. The expression of PKC and Erk were detected with immunohis-tochemistry. The expression of Erk mRNA was examined by in situ hybridization method. The data was analyzed by SPSS.ResultsThe immunohistochemical results suggested that the expression of Erk and PKC protein in I/R group was higher than in sham group, and in I/R group, compared with cortex, the percentage of PKC and Erk immunoreaction positive cells in hippocampus was higher( P < 0. 01). In CGRP or NGF group, the expression of PKC in cortex and hippocampus was lower than in I/R group, while the expression of Erk was higher (P<0.01). In C&N group, the expression of PKC was lower than in I/R, CGRP or NGF group, and the expression of Erk was higher ( P <0.01). The result of ISH indicated that the expression of Erk mRNA in I/R group was higher than in sham group, and in I/R group, compared with cortex, the percentage of Erk mRNA positive cells in hippocampus was higher(P<0. 01). In CGRP or NGF group, the expression of Erk mRNA in cortex and hippocampus was higher than in I/R group, and in C&N group, the expression of ErkmRNA was higher than in I/R,CGRP or NGF group ( P <0. 01).DiscussionTransient cerebral ischemia may result in degeneration, necrosis, delayed neuron death ( DND) and/or apoptosis. While a brain tissue protector both safety and effective has not been found yet.In this study, the mechanism of protective effects on neuron by NGF and CGRP was explored. CGRP, the first active polypeptide found in 1982, existing extensively in the nerve tissue, could exaggerate cerebral vessels by bounding to its special receptor. NGF, one of the most important nerve neurotrophic factors, could bound to its receptor trkA to maintain the mature neuron alive, promotethe repaire of injured neuron, and participate the neuron apoptosis. Both of them could combine with their receptors and convey the signals into the nucleus through a series signal cascade pathway. PKC, also called C kinase, is a kind of protein kinase depending on lipid and Ca2 +. It is reported that PKC participates the cell information convey, such as hormones secretion, cell secretion and cell proliferation, and so on. Erk, one of the most important members in MAPK signal pathway, could convey the signals into the nucleus, and regulate the expression of special gene by activating the transcription factors.In our study, an novel model of whole cerebral ischemia/reperfusion induced by carotid artery negative pressure shunt in rats was applied. In...
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