Beneficial effects of ventromedial hypothalamus (VMH) lesioning on function and morphology of the liver after hepatectomy in rats.

Liver has a high regenerative capacity and restores its mass and function shortly after partial hepatectomy through increased proliferation and metabolic modification of hepatocytes. The proliferation of hepatocytes can be triggered by its mass reduction after hepatectomy or by the neural factors including lesioning of the ventromedial hypothalamus (VMH). In the present study, we examined the effect of VMH lesioning on liver regeneration in hepatectomized rats by evaluating liver function and morphology. We found that functional deficits caused by partial hepatectomy [prolonged prothrombin time (PT), increased indocyanine green (ICG) retention, and decrease in PAS (periodic Acid-Schiff staining)-positive hepatocytes] were restored by VMH lesioning at 1 week after the surgery, whereas these alterations disappeared at 4 weeks. Morphologically, lipid microdroplets, which are considered to be important for maintaining contiguous liver function via supplying fuel for cell proliferation, were found to accumulate in hepatocytes of the hepatectomized rats at early period (1 day) after partial hepatectomy. Interestingly, such lipid microdroplets were also detected in the VMH lesioned rats and the more abundantly in the VMH lesioned, hepatectomized rats up to 1 week after the surgery. In conclusion, our results suggest that VMH lesioning in rats promotes recovery of liver anatomically and functionally after partial hepatectomy by promoting cell proliferation process.