Effects of hyperbaric oxygen on the expressions of endothelin-1, endothelial nitric oxide synthase and endothelin A receptor in cerebral circulation blood vessel in the rabbit model of cerebral ischemia

Abstract

Objective To investigate the effects of hyperbaric oxygen (HBO) on the expressions of endothelin-1(ET-1), endothelial nitric oxide synthase(eNOS)and endothelin A receptor(ETAR)in cerebral circulation blood vessel in the rabbit model of cerebral ischemia. Methods Forty healthy adult New Zealand rabbits were randomly divided into 2 groups; the surgical group (n=30) and the control group (n=10). The rabbits in the surgical group were further divided into the HBO + cerebral ischemia group (n=15) and the simple cerebral ischemia group (n=15) in accordance with different treatment methods. In the surgical group, cerebral ischemia model was established by thread embolus method. The HBO + cerebral ischemia group was exposed to HBO at a pressure of 0.22 MPa(2.2 ATA)for 60 minutes, one session a day, for a succession of 3 days. In the sham surgical group, neck vessel was only separated and the incision was soon sutured. The animals in the sham surgical group and the cerebral ischemia group did not receive HBO exposure, had normal diet and left there intact for 3 days. Three days later, all the animals were sacrificed, and then immunohistochemical staining was performed by using ET-1, ETAR and eNOS antibodies, and observations were made on the expressions of ET-1, eNOS and ETAR in the internal carotid artery and basilar artery of the 3 groups. Results Experimental results indicated that there were expressions of ET-1, eNOS and ETAR in the internal carotid artery and basilar artery after HBO exposure. As compared with those of the sham surgical group and the cerebral ischemia group, the expression levels of ET-1 and ETAR in the internal carotid artery (51.6±2.1, 53.4±1.5)of the HBO + cerebral ischemia group were obviously higher than those in the basilar artery(20.3±2.6, 24.3±1.7), and eNOS expression level in the basilar artery(52.1±2.3) was significantly higher than that in the internal carotid artery(22.3±1.2). Conclusions HBO exposure could enhance ET-1 and ETAR expression levels in the internal carotid artery, and could improve eNOS expression in basilar artery, resulting in anterior circulation contraction and posterior circulation dilation. Key words: Hyperbaric oxygen; Endothelin-1; Endothelial nitric oxide synthase; Internal carotid artery; Basilar artery; Rabbits