Meeting Abstract
In the leech Hirudo verbana, each segmental ganglion has four pressure mechanosensory neurons (P cells) that innervate overlapping quadrants of the body wall. The excitation of one P cell by mechanical stimulation of the skin results in the inhibition of the other P cells within the body segment. The synaptic connections between P cells are not fully understood, but it has been hypothesized that the excited P cell stimulates an interneuron which in turn releases the neurotransmitter GABA at synapses with the other P cells. To test this hypothesis, it is necessary to first identify the GABA-producing cells in the leech nervous system. Using immunohistochemistry, we have identified three bilaterally symmetrical pairs of GABA-producing neurons in the midbody ganglia: one pair is located on the ventral surface of the anterior end of the ganglion, and the other two pairs are located on the dorsal surface of the anterior end. Our next step is to use intracellular electrophysiological recordings followed by dye injections to characterize and identify these three pairs of GABA-producing neurons. Once the neurons are identified, we will examine whether or not they have synaptic connections with the P cells.
