Epigallocatechin-3-gallate restores the Bcl-2 expression in liver of young rats challenged with hypercholesterolemia but not in aged rats: an insight into its disparity of efficacy on advancing age

Advanced age significantly increases cholesterol levels, however, when combined with a high cholesterol diet it not only leads to life-threatening conditions like atherosclerosis, but also plays a central role in the pathogenesis of hepatic damage and its complications. Even though extensive studies have been carried out to elucidate the causative factors that lead to hepatic steatosis associated with liver damage in young rats due to hypercholesterolemia, events that occur in aged rats where a different milieu is presented by up and down regulation of various genes co-existing, has not been extensively studied. Hence, this study comparatively evaluates the impact of hypercholesterolemic stress induced liver damage in young and aged rats and the efficacy of epigallocatechin-3-gallate to protect the liver in both young and aged rats with special reference to apoptosis. Moreover, the work has been designed to investigate whether aged rats act as better models for studying the efficacy of atheroprotective drugs. Male albino rats of the Wistar strain were used in this study. Basic biochemical assays along with apoptotic markers assayed in the current study revealed that treatment with EGCG significantly reverted the alterations in both biochemical and histological parameters in young and aged hypercholesterolemic rats when compared to their respective controls. However, the extent of reversion was far superior in young rats, when compared to aged rats. EGCG reduced hepatic Bax expression in both young and aged hypercholesterolemic rats. On the other hand, Bcl-2 expression was up regulated significantly in young hypercholesterolemic rats, but not in aged hypercholesterolemic rats on treatment with EGCG. This throws light on the efficacy of the treatment differing in young and aged rats as well; atheroprotective drugs shall be tested for their efficacy in aged hypercholesterolemic models.