NEUROTROPHIC FACTORS IN BRAIN SYNAPTIC PLASTICITY

Various intercellular signals influence the strength and mode of synap tic neurotransmission and contribute to synaptic plasticity. Such sign als include neurotransmitters, gas molecules, and protein factors. In response to certain neural stimuli, these molecules are liberated from presynaptic and postsynaptic neurons, glial cells, and immune cells a nd synergistically alter synaptic neurotransmission over the long or s hort term. The shortterm actions often involve presynaptic activities leading to long-term potentiation. However, it is now known that vario us protein factors including growth factors, cytokines, and neurotroph ic factors can produce not only such short-term effects but also long- term synaptic modification of presynaptic and postsynaptic neurons by altering the production of neurotransmitters and the expression of the ir receptors or synaptic organization. The present review focuses on t hese intercellular protein factors and discusses the way in which they regulate synaptic plasticity.