Behavior of collagen extracellular liver matrix during regenerative growth after partial hepatectomy or after stimulation by exogenous hepatotrophic factors. Study in rats.

During regeneration after partial hepatectomy, the hepatic parenchyma grows by reproducing its histological elements at different rates. The hepatic cells grow more rapidly and the collagen components of the extracellular matrix more slowly. This report studies the behavior of liver tissue collagen in intact livers, increased in size by stimulation with exogenous hepatotrophic factors, comparing them to regenerated livers after hepatectomy. The series consists of a group of rats (n = 4), seven days after 70% hepatectomy, with an average growth of the residual liver mass of 71.55% and another group (n = 4), seven days after stimulation of the intact livers with an average growth of 121.05%. The exogenous hepatotrophic factors administered intraperitoneally (portal) included glucose, amino acids, insulin, glucagon and triiodothyronine. The hepatic collagen content was compared by studying slides stained with Picrossirius and examined with an optical microscope attached to a computer with an image analyzing program. The hepatic collagen was reduced from 2.07% +/- 0.13 to 1.14 +/- 0.08 (a difference of 44.57%; P < 0.001) after hepatectomy and from 1.98% +/- 0.19 to 1.24% +/- 0.07 (difference of 37.46%; P < 0.01) after exogenous hepatotrophic factors stimulation. It was concluded that the production of collagen in hepatic growth initiating with intact livers stimulated by exogenous hepatotrophic factors, occurs with a time difference similarly to what is observed after 70% hepatectomy.

Enhancement of liver size by stimulation of intact rat liver with exogenous hepatotrophic factors.

In mammals, liver size is related to animal body weight at the 2.5 to 3% proportion, a ratio mediated by the afflux of hepatotrophic factors. Formulas capable of modifying this ratio have been developed in previous studies on the rat, with enhancement of liver size brought about by intraperitoneal (portal) infusion of exogenous factors such as glucose, amino acids, insulin, glucagon, vitamins, electrolytes, and triiodothyronine. However, the efficacy of these formulations was accompanied by increased animal mortality (PARRA et al.). The present study, which was carried out with small methodological modifications on a larger number of rats using daily intraperitoneal injections of a solution of exogenous hepatotrophic factors (40 ml/kg) for seven days, confirms the previous findings, with a 114.16 +/- 7.90% enhancement of liver size beyond the expected value for the body weight of the animal. However, the problem of animal mortality was not fully resolved.