HISTOLOGICAL AND PHARMACOLOGICAL INVESTIGATIONS OF THE 2 SYMMETRICALLY SITUATED GIANT-NEURONS, RPENLN AND LPENLN, IDENTIFIED ON THE ANTERIOR SURFACE OF THE PEDAL GANGLIA OF AN AFRICAN GIANT SNAIL (ACHATINA-FULICA FERUSSAC)

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  • 1 January 1986
    • journal article
    • research article
    • Vol. 85  (1) , 233-238
Abstract
1. Morphological and pharmacological investigations were made of two giant neurons, RPeNLN (right pedal nerve large neuron) and LPeNLN (left pedal nerve large neuron), situated symmetrically on the anterior surface of the pedal ganglia of an African giant snail (Achatina fulica Ferussac). 2. The two neurons (about 250-300 .mu.m in diameter) were the largest ones identified in the ganglia of the snail species. The axonal pathways of the two neurons were symmetrical; of their four main axonal branches, the three main branches innervated the ipsilateral pedal nerves, whereas the last main branch projected to the contralateral pedal nerves. 3. The pharmacological features of the two neurons were very similar. Both were inhibited markedly by dopamine [ minimum effective concentrations (MECs): 3 .times. 10-6-10-5 M], DL-octopamine (MECs 2 .times. 10-6 2 .times. 10-5 M), 5-hydroxytryptamine (MEC: 3 .times. 10-6 M), GABA (MEC: 3 .times. 10-4 M), L-homocysteic acid (MECs: 3 .times. 10-5-10-4 M) and erythro-.beta.-hydroxy-L-glutamic acid (MEC: 3 .times. 10-5 M). Acetylcholine showed varied effects, either excitatory or inhibitory, on the two neurons examined. No substances were found to have any marked excitatory effects on the neurons.