Abstract:OBJECTIVE: This study examined the expression of Bcl-2, Bax and cytochrome C (Cyt C) in nerve cells and the effect of hyperbaric oxygenation (HBO) therapy on the expression levels in a neonatal rat model of hypoxic-ischemic brain damage (HIBD). METHODS: Seven- day-old SD rats weighing 12-14 g were randomly assigned into four groups:Normal group (n=34), Sham -operated group (n=33), of which the left common carotid artery of the rats was isolated but not ligated, HIBD group (n=30) in which the rats were subjected to left common carotid artery ligation followed by 2 hrs of hypoxia (8% O_2) and HBO treated group (n=33). HBO treatment was administered by placing the pups in a chamber after HIBD (2 atmosphere absolute for 1 hr per day for 7 days) in the HBO treated group. The expression of Bcl-2 and Bax in nerve cells of the brain was determined by immunohistochemistry and Cyt C expression was determined by Werstern blot analysis. RESULTS: The expression rate of Bcl-2 protein in the HBO treated group was obviously higher than that in the HIBD group(64% vs 47%, P < 0.05)), although it was lower than in the Normal group (82%) and the Sham-operated group (79%)(both P < 0.05). The expression rate of Bax protein in the HIBD group (77%) was significantly higher than that in the Normal group (15%, P < 0.01) and the Sham-operated group (36%, P < 0.05). HBO treatment did not result in a decreased expression of Bax protein. Cyt C was weakly expressed in nerve cells of the Normal and the Sham-operated groups, but was strongly expressed in the HIBD group. HBO treatment significantly decreased the Cyt C expression. CONCLUSIONS: HBO treatment can induce the expression of Bcl-2 protein and decrease the release of Cyt C from mitochondria, thereby protects the nerve cells from apoptosis after HIBD.
