Expression and significance of semaphorin 3A and its receptor NRP-1 in a rat model of chronic hepatic encephalopathy

Objective To investigate the changes in the expression of semaphorin 3 A( Sema3 A) and receptor neuropilins-1( NRP-1) in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions in rats with hepatic encephalopathy( HE) and their possible significance. Methods A total of 40 Sprague-Dawley rats were randomly divided into control group and 1-,15-,and 30-day HE groups,with 10 rats in each group. Bile duct ligation and ammonium acetate by gavage were used to establish a rat model of chronic HE( type C).The behavioral and neurological changes were observed; ELISA was used to measure blood ammonia and related biochemical parameters; HE staining was used to observe morphological changes of the liver and brain tissue; real-time PCR was used to measure the mRNA expression of Sema3 A and NRP-1 in each brain region; immunohistochemistry and Western blot were used to measure the protein expression of Sema3 A and NRP-1 in the cerebral cortex and the hippocampal CA1,CA3,and DG regions. A one-way analysis of variance was used for comparison of continuous data between multiple groups,and the least significant difference t-test was used for further comparison between two groups. Results There were significant differences between the four groups in nerve reflex level,blood ammonia,and HE grade( F =76. 39,417. 07,and 71. 56,all P < 0. 001),and compared with the control group,the 1-,15-,and 30-day HE groups had significant increases in nerve reflex score,blood ammonia,and HE grade( all P < 0. 05). There were significant differences between the four groups in total bile acid,albumin,total bilirubin,aspartate aminotransferase,alanine aminotransferase,and alkaline phosphatase( F = 1022. 61,171. 56,685. 18,421. 01,675. 98,and 2405. 04,all P < 0. 001),and compared with the control group,the 1-,15-,and 30-day HE groups had a significant reduction in albumin( P < 0. 05) and significant increases in the other indices( all P < 0. 05). The pathological results showed that compared with the control group,the HE groups had varying degrees of degeneration,necrosis,and inflammatory cell infiltration in the liver,with the pathological signs of swelling,tortuous,and ruptured nerve axons in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions. There were significant differences between the four groups in the mRNA expression of Sema3 A and NRP-1( Sema3 A: F = 273. 83,158. 84,103. 59,and 128. 90,all P < 0. 001; NRP-1: F = 88. 78,173. 02,156. 44,and 289. 09,all P<0. 001),and compared with the control group,the 1-,15-,and 30-day HE groups had significantly higher relative mRNA expression of Sema3 A and NRP-1 in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions( all P < 0. 05). There were increases in the protein expression of Sema3 A and NRP-1 after modeling,and immunohistochemistry showed that the HE groups had positive staining of Sema3 A and NRP-1 in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions. Western blot showed that there were significant differences between the four groups in the protein expression of Sema3 A and NRP-1 in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions( Sema3 A: F = 835. 14,774. 16,282. 60,and 856. 29,all P < 0. 001; NRP-1 : F = 876. 59,472. 48,402. 36,and 207. 47,all P < 0. 001),and compared with the control group,the 1-,15-,and 30-day HE groups had significant increases in the protein expression of Sema3 A and NRP-1 in the prefrontal cortex and the hippocampal CA1,CA3,and DG regions( all P < 0. 05). Conclusion Sema3 A/NRP-1 is upregulated in the brain tissue of chronic HE rats and is involved in the pathophysiological process of nerve injury in HE.