Protective effects of chronic green tea consumption on age-related neurodegeneration.

Dietary antioxidant compounds, due to their pivotal role in the modulation of cellular redox mechanisms, are gaining attention of researchers in the field of brain aging and related degenerative diseases. In this perspective, green tea (GT) can be an excellent resource, as it contains large amounts of brain-accessible polyphenols. Many of these compounds are monomeric catechins, which have been shown to exert antioxidant effects, acting directly as radical scavengers or metal-chelators. In the current article, we review the general properties of GT, the direct antioxidant action of its polyphenols and the fine modulation of signaling systems related to survival and antioxidant defenses in the central nervous system of aging rats. The effects in the glutathione system and the activation of several transcription factors including cyclic AMP response element-binding (CREB) protein, levels of the brain-derived neurotrophic factor (BDNF) and the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) are given in detail. We discuss also the beneficial action of catechins in learning and memory with a particular focus on the hippocampal formation. We conclude that GT polyphenols can have a promising role in the reversal of age-related loss of neuronal plasticity and recovery after neuronal lesions associated with aging.