Definition

A neurotransmitter is a molecule released by neurons into the synaptic gap where it exerts its function on other neurons or other cells (muscle or gland). Key elements in the transmission of nerve impulses.

A neurotransmitter is a molecule released by neurons into the synaptic gap. These neurons are called pre-synaptic and contain large amounts of neurotransmitter in synaptic vesicles. Once released into the synaptic cleft the neurotransmitter diffuses and reaches the postsynaptic membrane where it exerts its effects by binding to its receptor. Receptors for neurotransmitters can be found in other neurons, muscle cells or gland cells. The cells carrying the receptors are called post-synaptic cells.

The recipients of these cells can be opened by ligand gated ion channels or G protein-coupled receptors Neurotransmitter function is to transmit a signal from the presynaptic cell to postsynaptic cell. Its effect can be excitatory if it tends to depolarize the membrane or inhibitory if repolarized. After acting is degraded or recaptured by the fast presynaptic cell.

Neurotransmitters can be classified according to their size:

* Small neurotransmitters, amino acids (glycine, glutamic acid, aspartic acid), derived from amino acids (GABA, histamine, serotonin and catecholamines) acetylcholine, ATP.

* Neuropeptides composed of more than 3 amino acids, somatostatin, vasopressin, oxytocin. Many of these neuropeptides also act as hormones, known as neurohormones.

Defects in synthesis, release, or degradation of neurotransmitters are involved in the pathogenesis of a number of neurological, muscular and psychiatric disorders.