HEPATIC REGENERATION INDUCES CHANGES IN LIPOPROTEIN-LIPASE ACTIVITY IN SEVERAL TISSUES AND ITS REEXPRESSION IN THE LIVER

We examined the expression of lipoprotein lipase (LPL) gene and LPL ac tivity following a two-thirds hepatectomy and during liver regeneratio n. In most of the tissues studied, LPL activity increased a few hours after partial hepatectomy,but soon returned to normal levels. The grea test increase was found in the adrenal glands, plasma and liver. This increase in LPL activity in the liver could be partially due to an inc rease in the influx of the enzyme from extrahepatic tissues. There is, however, also a reexpression of LPL mRNA in the liver after partial h epatectomy (during the first hours). It is well known that LPL is expr essed in the liver of neonatal animals, but progressively decreases du ring post-natal development, to reach adult levels around the time of weaning. Our results show by the first time that the remaining liver r e-expresses LPL gene during the regeneration process and that the hepa tocytes de-differentiate and acquire some of the neonatal characterist ics. The increase in LPL mRNA will contribute to the rise in LPL activ ity after hepatectomy. This presence of LPL could enable the liver to take up fatty acids from the circulating triacylglycerols, which are n eeded as energetic and plastic substrates during the process of hepati c regeneration.