Abstract: Objective To explore the effect of carnosine in the expression of B cell lymphomal/leukemia-2 (bcl-2) and bcl-2-associated X protein (bax) after focal cerebral ischemia in rats. Methods Thirty male SD rats (SPF scale) were randomly divided into 3 groups: sham-operated group, model group and carnosine treated group (n=10 for each group). The middle cerebral artery occlusion model (MCAO) was induced in model group and carnosine treated group. Rats were received carnosine [1 000 mg/(kg·d), orally] in carnosine treated group, and the other rats were received the same volume of normal saline (NS) in shame-operated group and model group. The neurological deficit score was used to evaluate the neurological function at 24 h and 72 h after MCAO. Morphological changes were observed by HE staining. TCC staining was used to label infarct volume, and immunohistochemistry was used to detect the expression of bcl- 2 and bax. Results Compared with model group, the score of neurological function and infarct volume were significantly declined in carnosine treated group at 72 h after injury (P<0.05 or P<0.01). The changes of ischemic impairment were lighter in carnosine treated group than that of model group. Compared with sham-operated group, the expression levels of bcl- 2 and the ratio of bcl-2/bax were decreased while the expression of bax was increased in model group (P<0.05). Compared with model group, carnosine could significantly increase the expression of bcl-2 and the ratio of bcl-2/bax, and reduce the expression of bax (P<0.01 or P<0.05). Conclusion Carnosine can enhance bcl-2 expression, decrease bax expression and increase the ratio of bcl-2/bax, which is likely to be one of the mechanisms of neuroprotection.

Key words: carnosine, brain ischemia, genes, bcl-2, bcl-2-associated X protein, bcl-2/bax