ABSTRACT
The excitatory amino acid, glutamate, and several of its agonists are known to produce locomotory activity in the lamprey (Brodin et al. 1985), rat (Kudo and Yamada, 1987) and the embryos and larvae of amphibians (Dale and Roberts, 1984; McClellan and Farel, 1985). It is hypothesized that glutamate acts as a neurotransmitter in the neuronal pathway that generates locomotion in these systems. In both the central and peripheral nervous systems of invertebrates, glutamate also acts as a neurotransmitter. For example, at many crayfish neuromuscular junctions, exogenously applied glutamate mimics the effects of the endogenous excitatory transmitter (Takeuchi and Takeuchi, 1964; Kawagoe et al. 1981). In other invertebrates, application of glutamate to central neurons produces a variety of responses depending on the neuron stimulated and the preparation (Walker et al. 1980; Shinozaki, 1988). However, in no invertebrates has glutamate been implicated in eliciting any centrally generated motor patterns.
