ABSTRACT
There is considerable evidence that synapses in the adult as well as the developing brain are continually being formed and removed in a process called synaptic plasticity (21,65,80). The majority of excitatory synapses in the brain are glutamatergic and are formed mainly on dendritic spines. Spines are continually changing their shape and numbers. There must therefore be specific biochemical mechanisms mediating this activity. Some of these mechanisms involve various growth factors such as nerve growth factor (NGF). Others involve the interaction of neuromodulators such as the biogenic amines acting on their specific receptors. The receptors activate postsynaptic cascades that involve cyclic nucleotides and phosphorylation of cytoskeletal proteins leading to growth of synaptic elements. The purpose of this chapter is to review the evidence that free radicals derived from oxygen, nitrogen, and catecholamines might also play a role.
