A role for GABA sub(A) receptors in the modulation of Paramecium swimming behavior

The presence in Paramecium of gamma -aminobutyric acid A-type receptors (GABA sub(A)) and the capability of the protozoon to synthesize and release the GABA neurotransmitter into the environment have already been demonstrated. This study investigates the involvement of the GABA sub(A) complex in the...

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Bibliographic Details
Published in:Neuroscience letters 2005-10, Vol.386 (3), p.179-183
Main Authors: Bucci, G, Ramoino, P, Diaspro, A, Usai, C
Format: Article
Language:English
Subjects:
Paramecium primaurelia
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Summary:The presence in Paramecium of gamma -aminobutyric acid A-type receptors (GABA sub(A)) and the capability of the protozoon to synthesize and release the GABA neurotransmitter into the environment have already been demonstrated. This study investigates the involvement of the GABA sub(A) complex in the swimming control of the ciliated protozoon. The GABA sub(A) receptors were pharmacologically activated by the selective agonist muscimol and the effect on Paramecium primaurelia swimming behavior was analyzed. Paramecium normally swims forward, but the activation of GABA sub(A) receptors induced a peculiar response, characterized by alternate periods of whirling and forward swim. This effect was inhibited by the GABA sub(A) selective antagonists bicuculline and picrotoxin in a dose-dependent manner. Moreover, the application of benzodiazepines did not enhance the agonist action but only reduced it. Response to muscimol was also suppressed by nimodipine, a selective antagonist of dihydropyridine-sensitive calcium channels. This inhibition suggests that an inflow of calcium ions through L-type channels mediates the muscimol-induced swimming behavior.
ISSN:0304-3940
DOI:10.1016/j.neulet.2005.06.006