Expression and phosphorylation of p66Shc in young and old rats subjected to oxidative stress
Background: A well-established method for prolonging life-span is calorie restriction (CR); 40% below baseline is commonly used. Mechanisms behind the efficacy of CR are not understood and have not been studied extensively in the kidney, an organ that does not age well, partly via the effects of oxidative stress. Ablation of p66Shc also prolongs lifespan. This study examined p66Shc expression and activation in rats of different ages and diets subjected to oxidative stress after ischaemia-reperfusion (IR).
Methods: Protein and histology from kidneys (3-month and 2-year old female rats) were analysed. Rats were untreated or subjected to 45-minute bilateral renal IR (studied at 24hrs and 4 days). Groups were further separated into normal diet, 40% CR or vitamin E supplement. Analyses included plasma lactate dehydrogenase (LDH), fibrosis, iron, lipofuscin and inflammatory cell infiltration, and spatial and/or temporal expression patterns of Bcl-2, Bax, p66Shc and phospho-p66Shc.
Results: In control rats, LDH levels did not increase with ageing. In IR animals, LDH increased in all groups but showed great variability with ageing, exemplifying an inherent problem in ageing research even when using an inbreed population. There was no significant difference in expression of p66Shc amongst groups. However, phospho-p66Shc was generally lower in young compared to aged, and in young IR rats, the level of phospho-p66 decreased significantly with CR, while the opposite occurred in aged rats subjected to IR and CR.
Conclusions: Expression and activation of p66Shc are modified by diet, age and oxidative stress in the rat kidney.