Effect Of BFGF On Neuronal Apoptosis And The Expression Of C-myc And CyclinD In Rats Following Cerebral Ischemia-reperfusion Injury

Object:To investigate the role of c-myc and cyclin D in rats'brain tissues following cerebral ischemia-reperfusion injury by observing the number of apoptotic neurons in CA1 region of hippocampus and parietal cortex, TUNEL-positive cell number, the expression of C-myc and Cyclin D protein, respectively. And to examine the influence of basic fibroblast growth factor (bFGF) on the expression of c-myc and cyclinD protein in rats'brain tissues following cerebral ischemia-reperfusion injury.Method: The model of cerebral ischemia-reperfusion injury in rats was established according to the previous report by Longa and the animals were randomly divided into 4 groups: control group,sham operation group, ischemia-reperfusion (I/R) group and bFGF-treated group. HE staining, TUNEL staining and immunohistochemical staining were then performed using different samples. The TUNEL-positive cell number in CA1 region of hippocampus and parietal cortex and the expression of c-myc and cyclin D protein were determined.Results: (1) Neuronal apoptosis was observed in HE stained slices under the optical microscope. The morphological charateristic of apoptosis was found. The nuclear condensation and shift appeared at 12h and peaked at 24h after reperfusion. The neuron death were observed in the center of necrosis, the shape of neurons became indistiguishable, the structure was destroyed and vacuolization in the cytoplasm was found. In the margin of necrosis, nuclear condensation was obvious, nucleus was deeply stained and eosinophilic cytoplasm became clearer. There was no significant changes in control or sham group. However, in I/R group, the loss of neurons in CA1 region of hippocampus and parietal cortex was increased compared to that in sham group. Basic FGF treatment could reduce the loss of neurons and improve the alive cell numbers in CA1 region of hippocampus and parietal cortex at different time point.(2)TUNEL-stained slices were observed under the optical microscope. There were quite few number of TUNEL-positive cells in sham or control group. In contrast, there were many TUNEL-positive cells in I/R group , and the positive cell number peaked at 24h after reperfusion. There was significant difference in positive cell numbers between control and I/R group (p<0.01). Compared to I/R group, positive cells were reduced in bFGF-treated group and the difference was singnificant (p<0.05).(3) C-myc stained slices were observed under the optical microscope. There were quite few numbers of c-myc positive cells in sham group. However, there were much more c-myc positive cells in I/R group at different time points and the peak of the positive cell number appeared at 24h after reperfusion. There was significant difference in the average optical density (OD) between the two groups (p<0.01). The positive cell numbers wre fewer in bFGF-treated group compared to that in I/R group and the difference in OD was significant (p<0.05).(4) Cyclin D stained slices were observed under the optical microscope. There were quite few numbers of cyclin D positive cells in sham group. However, there were much more cyclin D positive cells in I/R group at different time points and the peak of the positive cell number appeared at 24h after reperfusion. There was significant difference in the average optical density (OD) between the two groups (p<0.01). The positive cell numbers wre fewer in bFGF-treated group compared to that in I/R group and the difference in OD was significant (p<0.05).Conclusion: (1)The neuronal apotosis in CA1 regions of hippocampus and cortex induced by cerebral ischemia-reperfusion injury in rats ws correlated closely with the expression of c-myc and cyclin D proteins in damage area.(2) Basic FGF has the neuroprotective effects on cerebral I/R injury in rats. It can reduce the neuronal apoptosis that was correlated with its inhibition of the expression of apoptotic regulation gene c-myc and cyclin D protein.