3H‐GABA uptake selectively labels identifiable neurons in the leech central nervous system

Abstract

Segment ganglia of the leech ventral nerve cord synthesize the neurotransmitter γ‐aminobutyric acid(GABA) when incubatyed in the presence of the prescursor glumate, suggesting that there may be GABA‐ergic neurons in the leech nerve cord. GABA‐accumulating neurons of the two taxonomically distant leech species, Haementeria ghilianii and Hirudo nedicinalis, have been labeled by takeing advantage of their high‐affinity uptake system for the neurotransmitter. Autoradiography of sectioned segmental ganglia previously exposed to ³H‐GABA reveals a reproducible pattern of about thirty ³labeled neurol cell bodies are bilaterally paired, although some apparently unpaired cell bodies also accumulate label. Neuronal processes were reproducibly labeled by GABA uptake and could be traced in the neuropil through commissures and fiber tracts into the segmental nerve roots and interganglionic connectives, respectively.