neurotransmittere

Neurotransmittere are chemical messengers that enable neurons to communicate across synapses with other neurons, muscle cells, or glandular cells. They are stored in presynaptic terminals and released in response to an arriving action potential, allowing them to bind to receptors on the postsynaptic cell. The resulting effect may be excitatory or inhibitory, depending on the receptor and cell type.

Two broad classes are often distinguished: small-molecule transmitters (such as acetylcholine, dopamine, norepinephrine, serotonin, glutamate, and GABA) and neuropeptides (such as substance P and vasopressin). Receptors include ionotropic receptors, which are ligand-gated ion channels that produce fast postsynaptic potentials, and metabotropic receptors, which are G protein–coupled and produce slower, modulatory effects.

After release, neurotransmitters are cleared from the synaptic cleft by reuptake into the presynaptic neuron, enzymatic degradation, or uptake by surrounding glial cells. Termination of signaling is essential to reset synapses and regulate signal strength and duration.

Role and clinical relevance: neurotransmittere underpin a wide range of functions, including sensation, movement, mood, learning, and memory. Dysfunctions in neurotransmitter systems are associated with many conditions, such as Parkinson's disease (dopaminergic loss), depression (serotonergic and noradrenergic changes), schizophrenia (dopamine and glutamate dysregulation), and epilepsy (glutamate versus GABA balance). Many drugs target these systems to treat disease, including selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, acetylcholinesterase inhibitors, and dopaminergic agents.