ABSTRACT
This chapter offers some plausible explanations for some of the confusion surrounding the functional significance of the neuroexcitatory action of glutamate. The realization in the early 1950s that synaptic transmission in the central nervous system (CNS) of vertebrates is predominantly chemically mediated provided impetus to discover the chemical agents mediating this function. This "universal" excitatory action coupled with the ubiquitous occurrence of glutamate throughout the CNS, and in all tissues, was contrary to the prevailing view of what the biological characteristics of a neurotransmitter should be. The numerous published studies dealing with the putative neurotransmitter function of glutamate have provided a wealth of confusing and seemingly conflicting data. The functional significance of the depolarizing action of glutamate on glial cells is not known, but one possibility is that glutamate may evoke the release of taurine, which may cause a generalized inhibitory effect on nearby neurons. Glutamate may also be a neurotransmitter at some synapses in mollusks.
