Necroptosis specific inhibitor-1 inhibits necroptosis in rat brain and improves brain injury after cardiac arrest

Abstract

To explore the effects of necroptosis specific inhibitor-1 (Nec-1) on brain injury in rats after cardiac arrest and its mechanism. A total of 24 Sprague-Dawley (SD) rats were divided into Sham group, model group and Nec-1 group (n = 8 per group) according to random number table method. In the Sham group, only general surgical procedures were underdone without inducing cardiac arrest. In the model group, the rats were subjected to asphyxial cardiac arrest followed by cardiopulmonary resuscitation (CPR) at 6 minutes after cardiac arrest. In the Nec-1 group, Nec-1 of 1 mg/kg was administered after cardiac arrest, and CPR was performed at 6 minutes after cardiac arrest. At 72 hours after CPR, neurological deficit scores (NDS) were assessed, serum S100B levels were measured by enzyme linked immunosorbent assay (ELISA), receptor-interacting protein 3 (RIP3) expression in cerebral cortex and hippocampus was observed under immunofluorescence and positive rate was calculated, and the levels of RIP3 protein expression in brain were analyzed by Western blotting. At 72 hours after CPR, the rats in the model group showed obvious necroptosis and injury in brain. Compared with the Sham group, the NDS scores in the model group were significantly decreased [57.0 (52.7, 60.0) vs. 80.0 (80.0, 80.0), P < 0.05], the serum S100B was significantly increased (ng/L: 44.9±4.5 vs. 18.6±1.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly elevated [cerebral cortex: (31.7±4.8)% vs. (11.6±3.2)%, hippocampus: (28.4±0.8)% vs. (10.9±0.6)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly increased [RIP3 protein (RIP3/GAPDH): 0.708 (0.642, 0.722) vs. 0.408 (0.253, 0.504), P < 0.05]. After Nec-1 intervention, necroptosis and injury in brain were obviously improved. Compared with the model group, the NDS scores at 72 hours after CPR in the Nec-1 group were significantly increased [70.5 (68.5, 71.7) vs. 57.0 (52.7, 60.0), P < 0.05), the serum S100B was significantly decreased (ng/L: 31.9±2.7 vs. 44.9±4.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly lowered [cerebral cortex: (23.7±4.1)% vs. (31.7±4.8)%,hippocampus: (20.4±0.4)% vs. (28.4±0.8)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly declined [RIP3 protein (RIP3/GAPDH): 0.437 (0.379, 0.507) vs. 0.708 (0.642, 0.722), P < 0.05]. Nec-1 attenuated necroptosis of brain cells by inhibiting the expression of RIP3 protein, so as to reduce brain injury after cardiac arrest in rats.