Norepinephrine treatment and aging lead to systemic and intracellular oxidative stress in rats

Reactive oxygen species (ROS) play important roles in cellular senescence and organismic aging. Furthermore, they have been implicated in some of the adverse effects of chronic stress due to elevated peripheral levels of catecholamines. Here, we applied three different techniques to individually compare the systemic and intracellular oxidative stress in aged (23 months) and young (5 months) Sprague-Dawley rats, and in young rats treated for 12 or 24 h with norepinephrine (NE). Thiol groups of blood serum proteins (RSH) were determined by means of Ellman's reaction. Intracellular ROS were assessed in spleen cells and peripheral blood lymphocytes (PBL) by carbonylation of cellular (spleen) proteins as determined by immunoblotting (Oxyblot) and/or by means of 2',7'-dichlorofluorescein (DCF) fluorescence. As compared to the young, untreated controls, both old rats and NE treated young rats showed similarly lowered RSH values paralleled by elevated intracellular ROS levels or enhanced Oxyblot signals. Individual RSH values were highly significantly, negatively correlated with respective Oxyblot data as well as with DCF fluorescence. The results confirm the roles of ROS in aging and adrenergic stress in the rat model, and suggest that the decrease in RSH of blood serum may be taken as a valid indicator for the enhanced oxidative stress in lymphocytes.