Hepatic denervation and dyslipidemia in obese Zucker (fa/fa) rats

Human and animal studies increasingly point toward a neural pathogenesis of the metabolic syndrome, involving hypothalamic and autonomic nervous system dysfunction. We hypothesized that increased very-low-density lipoprotein-triglyceride (VLDL-TG) secretion by the liver in a rat model for dyslipidemia, that is, the obese Zucker (fa/fa) rat, is due to relative hyperactivity of sympathetic, and/or hypoactivity of parasympathetic hepatic innervation. To test the involvement of the autonomic nervous system, we surgically denervated the sympathetic or parasympathetic hepatic nerve in obese Zucker rats. Our results show that cutting the sympathetic hepatic nerve lowers VLDL-TG secretion in obese rats, finally resulting in lower plasma TG concentrations after 6 weeks. In contrast, a parasympathetic denervation results in increased plasma total cholesterol concentrations. The effect of a sympathetic or parasympathetic denervation of the liver was independent of changes in humoral factors or changes in body weight or food intake. In conclusion, a sympathetic denervation improves the lipid profile in obese Zucker rats, whereas a parasympathetic denervation increases total cholesterol levels. We believe this is a novel treatment target, which should be further investigated.