Reactive oxygen species induced oxidative stress, neuronal apoptosis and alternative death pathways*

Reactive oxygen species (ROS) are produced as a by-product of cellular metabolic pathways and function as a critical second messenger in a variety of intra-cellular signaling pathways. The excessive intracellu-lar generation of ROS on the other renders a cell oxidatively stressed. This involvement of ROS in nu-merous diseases has been documented and at differ-ent phases of the apoptotic pathway such as induction of mitochondrial permeability transition and release of mitochondrial death amplification factors, active-tion of intracellular caspases and DNA damage has been clearly established. Cell death by apoptosis is a part of normal development and maintenance of tis-sue homeostasis. Polychlorinated biphenyls, one o