RT Book, Section A1 Nestler, Eric J. A1 Hyman, Steven E. A1 Holtzman, David M. A1 Malenka, Robert C. SR Print(0) ID 1105915191 T1 Synaptic Transmission T2 Molecular Neuropharmacology: A Foundation for Clinical Neuroscience, 3e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 9780071827690 LK neurology.mhmedical.com/content.aspx?aid=1105915191 RD 2024/03/29 AB Synaptic transmission is a signal transduction process that begins with the action potential–dependent release of a neurotransmitter from a presynaptic terminal. The neurotransmitter then binds to and activates postsynaptic receptors that modify the electrical and biochemical properties of the postsynaptic cell.The major classes of neurotransmitters are amino acid transmitters, such as glutamate and GABA; monoamines, including dopamine, norepinephrine, and serotonin; acetylcholine; peptides; diffusible gases, such as nitric oxide; lipid-derived molecules, such as endocannabinoids; and nucleosides and derivatives, such as adenosine and ATP.Neurotransmitters are stored in small organelles called synaptic vesicles that fuse with the presynaptic terminal membrane and release their contents when an action potential invades the terminal and causes a rise in calcium due to activation of voltage-dependent calcium channels.A single neurotransmitter typically activates several different subtypes of receptors.Neurotransmitter receptors are classified as ligand-gated ion channels or G protein–coupled receptors.After being released, most neurotransmitters are transported back into the presynaptic terminal or into glia by specialized proteins called plasma membrane transporters. A different family of transporters is responsible for pumping neurotransmitter into synaptic vesicles.Neurotransmitter transporters are important targets of many antidepressant medications and psychostimulant drugs such as cocaine and amphetamines.The proteins that are responsible for the fusion of synaptic vesicles with the presynaptic plasma membrane, a process known as exocytosis, have been identified and extensively characterized. Some of these proteins are the targets of bacterial toxins (eg, tetanus and botulinum toxin) and black widow spider venom (α-latrotoxin).After exocytosis, synaptic vesicles are recycled and used again by repackaging them with neurotransmitter.