Putative Neurotransmitters in 'Aplysia': Distribution of Gamma- Aminobutyric Acid, Aspartate and Glutamate in Ganglia and Single Neurons
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
Pagination or Media Count:
The distributions of gamma-aminobutyric acid GABA, glutamate and aspartate in the nervous system of Aplysia have been measured. GABA was detected in each ganglion examined and in the foot muscle at concentrations ranging from 0.90 plus or minus 0.04 to 1.55 plus or minus 0.17 micro moles100 mg protein. Aspartate and glutamate were present in greater concentrations in nervous than nonnervous tissues. While ganglia glutamate concentrations were nearly equal, aspartate concentrations varied over twofold among the ganglia. Each identified neuronal cell body examined contained GABA at greater than millimolar concentrations and aspartate at concentrations ranging from 22 plus or minus 3 to 96 plus or minus 11 mM. An apparent correlation was found between the aspartate and GABA content of invertebrate neurons. These results are consistent with a possible neurotransmitter role for amino acids, particularly aspartate and GABA, in Aplysia.