Abstract
Activity-dependent changes of synaptic efficacy in the superior cervical ganglion (SCG) can be prevented by γ-aminobutyric acid (GABA). We have studied the effects of picrotoxin (PTX) on GABA-mediated inhibition of long-term potentiation (LTP) of synaptic transmission in the rat SCG. Compound action potentials were recorded extracellularly in the postganglionic internal carotid nerve in response to preganglionic nerve stimulation. PTX (100 μM) antagonized the inhibition by exogenous GABA (250 μM) of LTP induced by strong tetanic stimulation (20 Hz, 20 s, supramaximal stimulation, partial blockade of transmission by hexamethonium). Additionally, PTX alone (50 μM) facilitated the induction of LTP by a weak tetanus (20 Hz, 5 s, submaximal stimulation). These results further support previous data indicating that activation of GABA A-like receptors can prevent the occurrence of synaptic plasticity at this peripheral synapse. © 1997 Elsevier Science B.V. All rights reserved.
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