Expressions of activin A and caspase-3 in brain tissue of neonatal rats with hyperbilirubinemia

Abstract

Objective To investigate the expressions of activin A(ACT A)and caspase-3 in different severity of brain injuries of neonatal rats with hyperbilimbinemia. Methods Totally 100 7-day-old SD rats were randomly assigned to the normal control group(n=10)and the experiment group (n=90).The rats of experiment group were medially subdivided into 3 groups:T1,T2,and T3 groups according to the increased bilirubin injected intraperitoneally(T1,50 μg/g;T2,100 μg/g;T3,200 μg/g).The specimens were collected at each time point(0,4,8,12,24 h)after the bilirubin injection.The bilirubin contents in the brain and serum were measured and the degree of the brain edema was assessed by wet/dry weight ratios of the brain tissue.And we observed the pathological changes of brain tissue and the expressions of ACT A and caspase-3 by immunohistochemistry staining. Results The serum bilirubin content of T1 group was increased obviously at 8, 12 h compared with that in control group (P＜0.05). There was no significant difference in the brain bilirubin content, the brain edema and the expressions of ACT A and caspase-3 between T1 group and control group (P＞0.05). The bilirubin contents in the brain and serum,the brain edema and the expressions of ACT A rdnd caspase-3 of T2,T3 groups were increased respectively at each time points after the bilirubin injection (p＜0.01 vs control).There were positive relations between the brain bilirubin content and the brain edema, the expressions of ACT A rdnd caspase-3 (r=0.876,P＜0.01:r=0.886,P＜0.01;r=0.900,P＜0.01).The neurons of control and T1 groups had complete structure and lined up in order. The neurons of T2 and T3 groups shrank obviously,and normal structure and arrngement disappeared.In T2,T3 groups,the expression of ACT A began at 8 h, reached a peak at 12 h and was still in high level until 24 h after the bilirubin injection,while the expression of caspase-3 began at 4 h and peaked at 24 h after the bilirubin injection. The caspase-3 and ACT A positive cells were mostly located in cerebral conex and hippocampus.Cinclusions The expressions of ACT A and caspase-3 are increased and dynamic in different severity of brain injury in neonatal rats with hyperbilirubinemia.It indicates that both of them may play important roles in pathogenic procedure of brain injury in neonatal rats caused by hyperbilirubinemia. Key words: Activin A; Caspase-3; Rats,newbom; Hyperbilirubinernia