Influences of cirrhotic portal hypertension on rats' cognitive function and N-methyl-D-aspartic acid receptor 2B expression level

Abstract

Objective Research on the influences of cirrhotic portal hypertension on rats' hcongnitive function and N-methyl-D-aspartic acid receptor 2B(NR2B) expression level. Methods Thirty seven male SD rats were randomly divided into 2 groups. In the cirrhotic portal hypertension group (group A), 25 rats were inducted into portal hypertension rat model using carbon tetrachloride-peanut oil solution. The remaining 12 rats served as control group (group B). Step-down method and Y-maze method were used in both groups prior to modeling and 1, 3, 5, 7 d after modeling respectively to study their behavior. All rats were killed after testing and hippocampi were collected. RT-PCR was used to detect NR2B mRNA level in the hippocampi, and Western blot was used to detect NR2B protein expression level. Immuno-histochemical method was used to detect NR2B protein distribution changes. ELISA was used to detect the level of ALT and AST, superoxide dismutase (SOD), malondialdehyde (MDA), TNF-α, IL-1 and IL-6. Results The level of AST, ALT, TNF-α, IL-1, IL-6 and MDA in group A were (261±7), (178±7) U/L, (206±18), (0.46±0.11), (298±41) μg/L, (19.7± 2.5) μmol/L, which were much higher than in group B(P<0.01), while SOD level[(96.0±7.0) U/ml] was lower than in group B (P<0.01). The step-down latent time of group A was longer and the number of error in Y-maze was more than B group (P<0.01). NR2B mRNA level and NR2B protein expression in the hippocampi of group A rats were evidently lower than that in group B(P<0.01). NR2B immunohistochemical level was lower in the CA1 area of the hippocampi of group A rats than that of the group B (P<0.01). Conclusions Cognitive function were decreased in cirrhotic portal hypertension rats, with decreasing NR2B mRNA and protein expression level in the hippocampus as well. Key words: Cirrhotic of liver; Portal hypertension; Cognitive function; N-methyl-D-aspartic acid receptor 2B; Rat