Endothelin receptor-A (ET_a) inhibition fails to improve neonatal hypoxic-ischemic brain injury in rats

Cerebral hypoxia-ischemia (HI) is an important cause of mortality and disability in newborns. It is a result of insufficient oxygen and glucose circulation to the brain, initiating long-term cerebral damage and cell death. Emerging evidence suggests that endothelin receptor-A (ET_A) activation can play an important role in mediating brain damage. In this study, we investigated the role of ET_A receptor inhibition using ABT-627 in neonatal HI injured rats. Postnatal day 10 Sprague-Dawley rat pups (n = 91) were assigned to the following groups: sham (n = 28), HI (vehicle, n = 32), and HI with ABT-627 at 3 mg/kg (n = 31). The Rice-Vannucci model was used to induce ischemia by ligating the right common carotid artery, followed by a 2 h hypoxic episode using 8% oxygen in a 37°C chamber. Postoperative assessment was conducted at 48 h after injury and again at 4 weeks. At the acute time point, investigative markers included cerebral edema, infarction volume, and body weight change. Neurobehavioral testing was measured at 4 weeks post-injury. Our findings indicated that ABT-627 had no effect on the measured parameters. This study suggests that ET_A receptor blockade using ABT-627 post-treatment fails to improve neurological outcomes in neonatal HI injured rats.