The Effect Of TGF-β₁ On Expression Of Bcl-2 And Bax Protein After HIBD In Neonatal Rats

ObjectiveHypoxic-ischemic brain damage (HIBD) caused by perinatal asphyxia often leads to the death of neonates or severe neurological sequelae. It has been the single most problem in neonatal period. There is increasing evidence that transforming growth facter-betal (TGF-β₁) plays an important role in the pathogenesis of neonate hypoxic-ischemic brain damage. In our experiment HIBD model was established, different TGF-β₁ dosages were injected into the left lateral ventricle. Then we study the effects of TGF-β1 on expression of Bcl-2 and Bax protein. To explore the neuronal protective mechanism of TGF-β₁ . Our experiment may provide an efficacious means treatment for clinical therapy of neonatal HIBD.Methods1. Mading of HIBD model: Neonatal 7-day-old Wistar rats were under a middle anterior neck incision. The left common carotid artery was isolated and ligated, then the pups were exposed to hypoxic environment (8%O₂) for 2 hours. We observed rats behavior ability during hypoxic, then observed microscopical changes.2. Observing of behavior ability of rats: Observed turnover ability and levogirate ability when their tails are gripped of the each rat beforethe experiment or at 1 hour after hypoxia3. Expression of Bcl-2 and Bax protein . 48 seven-day-old Wistar rats were randomly assigned to the sham-operation group, HIBD group, saline-treated control group, TGF-P rtreated group. Each of TGF- 3 ,-treated group was divided into groups of high, middle and low dose. Different TGF-0, dosages were injected into the left lateral ventricle at 2 hour after hypoxia. We measured the expression of Bcl-2 and Bax protein at24 hour after injected by immunohistochemistry.Results1. Observing of behavior ability of rats;Before the experiment each rat is healthy. 1 hour after hypoxia, the sham-operated group is still healthy, while in the 40 rats which bare hypoxic-ischemic injury, 24 rats couldn' t turn themselves over and 33 rats become levogirating when their tails are gripped. There are 18 rats couldn't turn themselves and become levogirating when their tails are gripped.2. HE staining and the histological studySham-operated group: There was no obvious sign of neuronal damage and with cells of apparently normal appearance in the brain tissue. There was no edema and degenerated neurons.HIBD group: The edema in the brain tissue was apparent,the morphological alteration of the neuron were cellular shrinkage, cytoplasmic homogeneous eosinophilia, nuclear pyknosis, and the proliferation of glial cell appeared.3. Expression of Bcl² protein The level of Bcl² protein was low in Sham-operated group. After HIBD, the expression of Bcl-2 protein decreased significantly. Each of TGF- P ,-treated group was higher than HIBD group and saline-treated control group. There was no significant difference between saline-treated control group and HIBD group, each the group of large> normal > small dose of TGF-3, (p>0.05) . There was significant difference each the left groups (p<0. 05) .4. Expression of Bax protein The level of Bax protein was low in Sham-operated group. After HIBD, the expression of Bax protein decreased significantly. Each of TGF-P rtreated group was lower than HIBD group and saline-treated control group. There was no significant difference between saline-treated control group and HIBD group, each the group of largex normal - smal 1 dose of TGF-P t (p>0. 05) . There was significant difference each the left groups (p<0. 05) .5. The change of Bcl-2/Bax ratio After HIBD, the Bcl-2/Bax ratio decreased significantly. It increased in TGF-P ,-treated groups. There was no significant difference between saline-treated control group and HIBD group, each the group of large% normal ? small dose of TGF-P,(p>0.05) . There was significant difference each the left groups (p<0.05) .Conclusions1. We confirmed the success of the model HIBD in neonatal rats through observing the rats behavior ability and the histosspathology of braintissue.2. The neuronal protective mechanism of TGF-P i might be related to up regulate the expression of Bcl-2 protein, down regulate the expression of Bax protein and alter the Bcl-2/Bax ratio in brain tissue, consequently it could decrease the apoptosis of neuron after HIBD. Our conclusion may be useful for the clinical treatment of HIBD.