Polypeptide from chlamys farreri for intervention of the expression of Bcl-2 and Bax protein in the cerebral ischemic penumbra of rats

Ruowu SHEN; Yujun XIA

ABSTRACT

BACKGROUND:

Both apoptosis suppression gene Bcl-2 and apoptosis in duction gene Bax take parts in the apoptosis of neurons in ischemic penum bra. Whether would the polypeptide from chlamys farreri that is proved to be of anti-oxidation and anti-apoptosis in vitro protect the ischemic neurons from apoptosis?

OBJECTIVE:

To observe the effect of chlamys farreri on the Bcl-2 and Bax protein-associated apoptosis in penumbra and its role in neuron protection.

DESIGN:

A randomized trial.

SETTING:

Department of Anatomy, Medical College of Qingdao University.MATERIALS The trial was conducted in Nerve Anatomy Laboratory of Medical College of Qingdao University from March to April 2000. The subjects were 32 adult Wistar rats that were randomly and averagely assigned into 4 groups polypeptide chlamys farreri group, sterile water group, model control group and sham group. The chlamys farreri was provided by the Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences.

INTERVENTIONS:

Model of brain ischemia and reperfusion was made in rats in polypeptide chlamys farreri, sterile water and model control group by occlusion of middle cerebral artery. The model was not established in rats in sham group. The rats in chlamys farreri group received intraperitoneal injection of chlamys farreri of volume fraction 0. 1 at the dose of 0. 1 mL/kg each day for 2 days prior to modeling and an extra injection 15 minutes just before modeling. And the rats in sterile water group received intraperitoneal injec tion of sterile water with the dose of 0. 1 mL/kg each for two days and an extra injection 15 minutes before modeling. Those in model control group and sham group were exposed to nothing. Then models were established in rats in chlamys farreri, sterile water and model control group by inserting 4-0 nylons sutures from external carotid artery through bifurcation of carotid artery,extracranial and intracranial segments of internal carotid artery till the initial part of middle cerebral artery to make acute ischemia of middle cerebral artery perfusion area. The model was considered successful by the presentation of Horner' s syndrome, adduction-flexion of right forearm when tail being lifted and right turning during walk of the rat. The rats in sham group underwent the same procedures as that in the other groups except for the occlusion of middle cerebral artery. Then brains of the rats were taken for immunohistochemical determination of Bcl-2 and Bax proteins. The protein expression was expressed by absorbance of the products of their immunological reaction.MAIN OUTCOME

MEASURES:

The expression differences betweenBcl-2 and Bax proteins in penumbras of the groups.

RESULTS:

There were 32 rats entered the stage of analysis after complement of subjects. ① Bcl-2 expression in penumbra The absorbance in model control group and sterile water group were higher than that in sham group (0.453±0.048,0.510±0.061,0.211±0.023, F=683.78, q=21.13 to 24.74, P ＜ 0.01), and that in chlamys farreri group(0. 954 ±0. 059) was more than that in model control group and sterile water group( q = 38.08 to 41.69, P ＜ 0.01) . ② Bax expression in penumbra The absorbance in model control group and sterile water group were higher than that in sham group (0. 834 ±0. 082, 0. 790 ±0. 102, 0. 125 ±0. 017, F=590.44, q =49.57 to 51.98, P ＜ 0.01 ) ] and that in chlamys farreri group (0.471 ± 0. 045 ) was suppressed as compared with that in model control group and sterile water group(q=23. 80 to 26. 23, P ＜0. 01).

CONCLUSION:

Chlamys farreri is capable of increasing Bcl-2 protein and decreasing Bax protein in cerebral penumbra to brake the initiation of neuron apoptosis after ischemia-reperfusion and preserve neuronic function in penumbra.