Carbachol can be released at a cholinergic ganglionic synapse as a false transmitter

Area of Science:

• Neuroscience
• Neurophysiology
• Synaptic Transmission

Background:

• Cholinergic neurons play a crucial role in synaptic communication.
• Understanding neurotransmitter function is key to deciphering neural circuits.
• Aplysia buccal ganglion provides a model system for studying basic neuronal mechanisms.

Purpose of the Study:

• To investigate the quantal aspects of postsynaptic responses after presynaptic carbachol injection.
• To compare the effects of carbachol and acetylcholine on unitary channel currents.
• To determine if carbachol functions as a false transmitter in Aplysia neurons.

Main Methods:

• Statistical fluctuation analysis was employed to analyze postsynaptic currents.
• Carbachol and acetylcholine were applied iontophoretically.
• Presynaptic intracellular injections were performed, including acetylcholinesterase inhibition.

Main Results:

• Intracellular carbachol injection increased miniature postsynaptic current amplitude.
• The unitary channel current for carbachol was greater than for acetylcholine.
• Presynaptic carbachol injection restored transmission blocked by acetylcholinesterase inhibition.

Conclusions:

• Carbachol can act as a false transmitter, enhancing postsynaptic responses.
• The increased unitary channel current of carbachol explains its effect on miniature postsynaptic currents.
• Carbachol's ability to restore transmission highlights its potential as a neurotransmitter mimic.