[Expression of aquaporin-4 during brain edema in rats with thioacetamide-induced acute encephalopathy].
OBJECTIVE
To investigate the expression of aquaporin-4 (AQP4) during brain edema in rats with thioacetamide-induced acute liver failure and encephalopathy.


METHODS
The rat model of acute hepatic failure and encephalopathy was induced by intraperitoneal injection of thioacetamide (TAA) at a 24-hour interval for 2 consecutive days. Thirty-two SD rats were randomly divided into the model group (n = 24) and the control group (normal saline, n = 8). And then the model group was further divided into 3 subgroups by the timepoint of decapitation: 24 h (n = 8), 48 h (n = 8) and 60 h (n = 8). Then we observed their clinical symptoms and stages of HE, indices of liver function and ammonia, liver histology and brain water content. The expression of AQP4 protein in brain tissues was measured with Western blot and the expression of AQP4mRNA with RT-PCR (reverse transcription-polymerase chain reaction).


RESULTS
Typical clinical manifestations of hepatic encephalopathy occurred in all TAA-administrated rats. The model rats showed the higher indices of ALT (alanine aminotransferase), AST (aspartate aminotransferase), TBIL (total bilirubin) and ammonia than the control rats (P < 0.05). The brain water content was significantly elevated in TAA-administrated rats compared with the control (P < 0.05). The expressions of AQP4 protein and mRNA in brain tissues significantly increased in TAA-administrated rats (P < 0.05). In addition, the expressions of AQP4 protein and mRNA were positively correlated with brain water content (r = 0.536, P < 0.01; r = 0.566, P = 0.01).


CONCLUSIONS
The high expression of AQP4 in rats with TAA-induced acute liver failure and encephalopathy plays a significant role during brain edema. AQP4 is one of the molecular mechanisms for the occurrence of brain edema in hepatic encephalopathy.
Department of Anesthesiology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
Li-Qing
LQ
Wang
Sheng-Mei
SM
Zhu
Heng-Jun
HJ
Zhou
Cai-Fei
CF
Pan
D000818:Animals; D051401:Aquaporin 4 / Q000378:metabolism; D001927:Brain Diseases; D001929:Brain Edema / Q000378:metabolism; D004195:Disease Models, Animal; D006501:Hepatic Encephalopathy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013853:Thioacetamide
D051401:Aquaporin 4; D013853:Thioacetamide