Premium
Evidence for the presence, synthesis, immunoreactivity, and uptake of GABA in the nervous system of the snail Helisoma trivolvis
Author(s) -
Richmond J. E.,
Bulloch A. G. M.,
Bauce L.,
Lukowiak K.
Publication year - 1991
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903070112
Subject(s) - biology , neuroscience , central nervous system , glutamate receptor , neurotransmitter , lymnaea stagnalis , nervous system , gamma aminobutyric acid , snail , anatomy , biochemistry , receptor , ecology
In the present study several techniques were employed to test the hypothesis that gamma‐aminobutyric acid (GABA) is a neurotransmitter in the central nervous system (CNS) of the pond snail Helisoma trivolvis (Mollusca, Pulmonata). First, by using chromatographic techniques, the presence of GABA and its differential distribution among the ganglia constituting the CNS was demonstrated. Second, de novo synthesis of 3 H‐GABA from 3 H‐glutamate was shown by the CNS. Levels of both endogenous and newly synthesized GABA were greatest in the buccal, cerebral, and pedal ganglia. Third, indirect immunohistochemistry of wholemounts revealed a central network of GABA‐like immunoreactive neurons. With the possible exceptions of two pairs of fibers in nerve trunks, all projections from GABA‐immunoreactive neurons were confined to the CNS, suggesting a predominantly central role for GABA. Stained neurons were found on the dorsal surface of the buccal ganglia and throughout the cerebral and pedal ganglia. No GABA‐immunoreactive cell bodies were observed in the parietal, pleural, or visceral ganglia. Finally, uptake of 3 H‐GABA was examined autoradiographically in sectioned ganglia. A pattern of radiolabelled cells was observed that closely resembled the distribution of GABA‐immunoreactive neurons. The data described above fulfill several criteria necessary to establish GABA as a transmitter in the nervous system of Helisoma . Taken together with previously obtained pharmacological evidence demonstrating that GABA acts on Helisoma central neurons, GABA is considered to be a strong candidate for a neurotransmitter in Helisoma .