Liver denervation increases the levels of serum triglyceride and cholesterol via increases in the rate of VLDL secretion

Abstract

Intra-hepatic metabolism of lipids is subject to hormonal, metabolic and neural regulation, but little is known about the latter. Catecholamines stimulate the output of glucose and inhibit the release of very low density lipoproteins (VLDL) from the liver. To investigate the effects and involved mechanism of liver denervation on the levels of serum and liver lipids. Two groups of male rats were taken as control and cases and the liver was denerved chemically by 90% phenol in the case group. On the fourth day of the operation, blood samples were taken and the liver homogenized for lipid and glycogen analyses. Cholesterol, triglyceride, HDLc and glucose were measured enzymatically. Total phospholipids were analyzed by the measuring of liberated inorganic phosphate in organic phase. Glycogen was extracted by ethanol and analyzed by phenol/sulphuric acid reagent. In a separate experiment, the rate of triglyceride secretion was measured in vivo by using tyloxapol and compared in two groups. The serum concentrations of triglyceride (73.7 ± 6.3 vs. 45.8 ± 1.6 mg/dL, P ≤ 0.003) and cholesterol (87.7 ± 3.7 vs. 67.4 ± 2.2mg/dL, P ≤ 0.001) were significantly higher in the denerved compared with the control group. The serum glucose showed a significant decrease (170.5 ± 5.4 vs. 140.6 ± 10.7 mg/dL, P ≤ 0.04) in the denerved group while HDLc had no significant difference between the two groups. Denerved rats compared to the control rats had the higher levels of hepatic glycogen (201.1 ± 20.6 vs. 100.7 ± 19.9 mg/g liver, P ≤ 0.02). The contents of liver triglyceride, cholesterol and total phospholipids did not differ significantly between two groups. The mean rate of triglyceride secretion from the liver increased in the denerved group (276.1 ± 16.1 vs. 230.6 ± 7.7 mg/dL.h, P ≤ 0.03). Liver denervation increases the levels of serum triglyceride and cholesterol via increases in the rate of VLDL secretion. Liver innervation plays a role on the regulation of metabolism of lipids and carbohydrates.