Increased Expression and Specific Localization of Cathepsins E and D in Vulnerable Brain Regions of Aged and Postischemic Rats

Most neuronal cell death could be classified into apoptosis and necrosis on the basis of morphological analysis. Apoptosis is initially characterized by condensation and fragmentation of nucleus mainly due to the increased expression of endonucrease (1). Apoptosis is an important biological pathway for programmed cell death which occurs during development. On the other hand, necrosis is primarily characterized by destruction of the cell membrane and the cytosolic cell structures, but lysosomes are rather intact until advanced stage of neuronal degeneration. Necrosis is an accidental neuronal cell death and includes cell death due to aging and ischemia. In the course of necrotic type of neuronal degeneration, a variety of lytic enzymes normally present in the cytoplasm are considered to be activated.