The effects of chemical sympathectomy on liver regeneration in rats undergoing partial hepatectomy

The study aims to analyze experimentally the effects of chemical sympathectomy on liver regeneration in rats undergoing partial hepatectomy (PH). In our study, there were four main groups with sixteen rats in each group (Group 1: control, Group 2: sympathectomy, Group 3: control+partial hepatectomy, Group 4: sympathectomy+partial hepatectomy).The groups were then distributed into two sub-groups as Group A and Group B with eight rats in each group. Hepatectomy was performed on Group A two days after the control operation or partial hepatectomy; whereas in Group B it was performed ten days after the operation. To form chemical sympathectomy, each rat was administered 6-Hydroxydopamine hydrobromide (100 mg/kg/day, intraperitoneal) for 5 days and normal saline (1 mL, intraperitoneal) was also administered to control groups as placebo for 5 days. Before the end of the experiment; weighing measurements were made, blood and liver samples were obtained, and they were sent to the biochemistry and pathology laboratories. Regenerated liver ratio was used as the morphological parameter. HGF, TNF-?, IL-6 measurements were performed on blood samples obtained as biochemical parameters. Tissue samples were analyzed histopathologically to determine mitotic index, PCNA, Ki-67 and apoptotic index. In our study, chemical sympathectomy was found to increase not significantly theregenerated liver ratio in the rats with PH on the 2nd day compared to the control group. The increase was later found to be significant on the 10th day. While the effect of chemical sympathectomy on liver regeneration rate was much more significant in the rats without PH on the 2nd day, it tended to decline on the 10th day. Moreover, PHsignificantly increased the liver regeneration rate independently from chemical sympathectomy. When our findings on the HGF level were assessed; chemical sympathectomy was found to increase the HGF level significantly in the rats with PH on the 2nd day, compared to all other groups. However, the increase was observed to lose its significance and it approached the level of the control group in the measurements made on the 10th day. In our study, chemical sympathectomy and PH did not cause any significant change in the data related to TNF-? on the 2nd day. On the other hand, when the data obtained on the 10th day were analyzed, chemical sympathectomy was found to increase the TNF-? level significantly in the rats with PH, compared to all other groups. According to our findings related to IL-6; both chemical sympathectomy and PH increased the IL-6 levels on the 2nd day significantly compared to control groups. Furthermore, the IL-6 levels returned to the basic values on the 10th day, independently from chemical sympathectomy and PH. Here, a remarkable finding was that chemical sympathectomy increased the IL-6 levels significantly in the rats without PH on the 2nd day and the effect was removed or concealed when PH was performed. In our study, mitotic index was more significantly increased in the rats with PH on the second day and also it was found to increase significantly in the rats with chemical sympathectomy. Another remarkable finding was that the significant increase in all groups except the control group became much more notable on the 10th day. Our findings regarding PCNA were found out that PCNA levels significantly increased both in the rats with chemical sympathectomy (moreremarkable than the others) and in the rats with PH significantly on the 2ndday compared to the control group. While the significant increase tended to decline in the rats with PH based on the measurements made on the 10th day, it continued to increase in the rats with chemical sympathectomy. In our study, it was observed that both chemical sympathectomy and PH increased Ki-67 levels significantly on the 2nd day, compared to the levels in control groups. The significant effect was not aggravated by the combination of chemical sympathectomy and PH. On the other hand, the significant effects continued on the 10th day, but that time the effect of chemical sympathectomy was a little aggravated in the rats with PH but it was not significant. Our findings as to apoptosis demonstrated that the apoptotic index was more significantly increased in the rats with PH on the 2nd day. It also increased in the rats with chemical sympathectomy significantly compared to the control group. Performing the PH after the chemical sympathectomy led to an insignificant increase in the apoptotic index. In the analysis conducted on the 10th day, it was found that the apoptotic index increased significantly only in the rats with PH performed after chemical sympathectomy. However, the apoptotic index was observed to regress to the control values in the other two groups (groups with chemical sympathectomy only or PH only) When these all data are considered; it is suggested that chemical sympathectomy is effective in a regeneration process that becomes prominent on the 2ndafter the PH through cell proliferation related to both HGF and IL-6. Moreover, it may also be suggested that apoptotic mechanisms related to TNF-á activate and hinder hyperplasia being much higher than the organism needs in order to balance the hyperplasia on the 10th day. Accordingly, further studies are needed to determine the effects of these complex interactions and the role of autonomic nervous system on the liver regeneration process.