Experimental study of non-alcoholic fatty liver disease (NAFLD) on a model of starving chickens: Is generalization of steatosis accompanied by fibrosis of the liver tissue?

The objective of this work was to study the mechanism of liver parenchyma development under the influence of restriction of diet. Useful information is presented about the pathologic features associated with diet restriction in a chicken animal model of NAFLD. There were 96 chickens of two genotypes, Ross 308 and Cobb 500, in the experiment. The control group was fed a standard mixture ad libitum (ADL). The first experimental group, under restriction from the age of 2 weeks, was fed 80% ADL. The second experimental group was fed 65% ADL from the age of 2 weeks. There were 16 animals in each group. The experiment lasted 5 weeks. Liver parenchyma samples were obtained at the age of 35 days by the necropsy method and then processed by standard histologic methods. The slices were stained by standard staining: hematoxylin-eosin and by Sirius red kit for collagen type I and reticulin visualization. Hepatocyte diameter and the proportion of interstitial tissue to the parenchyma of the liver were measured objectively. Microvesicular liver steatosis was observed after 35 days of restriction. Hepatocyte diameter was significantly influenced by sex, genotype, and the experimental group. The proportion of interstitial tissue to the liver parenchyma was highly influenced by genotype and group, but there were no interactions. An increase in the steatosis histologic grade is associated with inflammatory changes, with decrease of hepatocyte diameter and with a decreasing proportion of interstitial tissue to the liver parenchyma. The results show that early restriction is not associated with the development of fibrosis of the liver tissue.