ABSTRACT
This chapter provides an overview of synaptic neurotransmission and the ways in which clinically useful antiepileptic drugs affect that transmission. The major precursor of norepinephrine (NE) and dopamine synthesis in brain is tyrosine which is formed from phenylalanine in the liver. Neurons which synthesize NE contain dopamine-ß-hydroxylase which converts dopamine to NE. The major amino acid precursor of 5-Hydroxytryptamine synthesis is tryptophan, which is an essential amino acid supplied in the diet. Tryptophan, like tyrosine, is a neutral amino acid that also gains entry into the brain by the large neutral amino acid transporter. The rate-limiting step in the overall conversion of tryptophan to serotonin is the first step which is catalyzed by tryptophan hydroxylase and results in the conversion of tryptophan to 5-hydroxytryptophan. The available evidence suggests that serotonin, like the catecholamines, is stored in membrane-bound synaptic vesicles seen inside nerve terminals with electron microscopy.
