Apoptosis or programmed death is a biological phenomenon, which is essential for the development and maintenance of a cell population. In this process, senescent or damaged cells are eliminated after activation of a cell death program involving participation of pro-apoptotic molecules (Fas, Fas-L, Bax, caspases 2, 3, 6, 7, 8 and 9). Molecule activation causes typical morphological changes, such as cell shrinkage, loss of adhesion to the extracellular matrix and neighboring cells, chromatin condensation, DNA fragmentation and formation of apoptotic bodies. Anti-apoptotic molecules (Bcl-2, FLIP) block the emergence and evolution of these cell changes and prevent cell death. The balance between molecules pro and anti-apoptotic ensures tissue homeostasis. When apoptosis is out of control, it contributes to the emergence of several neoplastic, autoimmune and neurodegenerative diseases. Several inducing and inhibitors of apoptosis agents are recognized as potential weapons in the fight against diseases related to proliferation and cell death disorders among which stand out hormones. Melatonin has been reported as important anti-apoptotic agent in various tissues by reducing cell calcium uptake, modulating expression of anti-oxidants and decreasing pro-apoptotic protein, such as Bax. The knowledge of new agents capable to act on the course pf apoptosis is important and of great value for developing further therapies against many diseases. Thus, the objective of this review was to elucidate the main aspects of cell death by apoptosis and the role of melatonin in this process.
Melatonin; Pineal gland; Apoptosis; Apoptosis regulatory proteins; Caspases