Presynaptic ionotropic receptors and control of transmitter release

Presynaptic nerve terminals are dynamic structures that release vesicular packages of neurotransmitter, affecting the activity of postsynaptic cells. This release of transmitter occurs both spontaneously and after the arrival of an action potential at presynaptic terminals. How is the release process modulated? Although ionotropic receptors are commonly regarded as postsynaptic elements that mediate the effect of the released chemical signals, a wide variety of ionotropic receptors have also been found on presynaptic membranes near release sites, where they powerfully influence vesicle fusion. Here, we provide an overview of the presynaptic ionotropic receptors that modulate transmitter release, focusing on their proposed mechanisms of action.