Neurotransmitter

Neurotransmitters are endogenous chemicals that enable neurotransmission.

Neurotransmission (Latin: transmissio "passage, crossing" from transmittere "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and react with the receptors on the dendrites of another neuron (the postsynaptic neuron) a short distance away.

A released neurotransmitter is typically available in the synaptic cleft for a short time before it is metabolized by enzymes, pulled back into the presynaptic neuron through reuptake, or bound to a postsynaptic receptor.

Reuptake is the reabsorption of a neurotransmitter by a neurotransmitter transporter located along the plasma membrane of an axon terminal (i.e., the pre-synaptic neuron at a synapse) or glial cell after it has performed its function of transmitting a neural impulse.

A released neurotransmitter is typically available in the synaptic cleft for a short time before it is metabolized by enzymes, pulled back into the presynaptic neuron through reuptake, or bound to a postsynaptic receptor. Neurotransmitters are released from synaptic vesicles in synapses into the synaptic cleft, where they are received by neurotransmitter receptors on the target cells.

A neurotransmitter receptor (also known as a neuroreceptor) is a membrane receptor protein that is activated by a neurotransmitter.

It is a type of chemical messenger which transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell.

Calcium ions bind to sensor proteins (synaptotagmin) on synaptic vesicles, triggering vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft.

Furthermore, Otto Loewi is credited with discovering acetylcholine (ACh)—the first known neurotransmitter.

Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals, and humans, as a neurotransmitter—a chemical message released by nerve cells to send signals to other cells, such as neurons, muscle cells, and gland cells.

Neurotransmitters are endogenous chemicals that enable neurotransmission.

Cell signalling systems such as hormone and neurotransmitter systems use endogenous substances.

Neurotransmitters are released into and diffuse across the synaptic cleft, where they bind to specific receptors on the membrane of the postsynaptic neuron.

A molecule that binds to a receptor is called a ligand, and can be a protein or peptide (short protein), or another small molecule such as a neurotransmitter, hormone, pharmaceutical drug, toxin, or parts of the outside of a virus or microbe.

The most prevalent transmitter is glutamate, which is excitatory at well over 90% of the synapses in the human brain.

It is also an excitatory neurotransmitter, in fact the most abundant one, in the vertebrate nervous system.

Major neurotransmitter systems include the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system, and the cholinergic system, among others. L-phenylalanine and L-tyrosine are both precursors for dopamine, norepinephrine, and epinephrine.

It functions both as a hormone and a neurotransmitter, and plays several important roles in the brain and body.

Neurotransmitters are stored in synaptic vesicles, clustered close to the cell membrane at the axon terminal of the presynaptic neuron.

Neurons are interconnected in complex arrangements, and use electrochemical signals and neurotransmitter chemicals to transmit impulses from one neuron to the next; axon terminals are separated from neighboring neurons by a small gap called a synapse, across which impulses are sent.

Binding of neurotransmitters may influence the postsynaptic neuron in either an inhibitory or excitatory way.

It may occur via direct contact between cells (i.e., via gap junctions), as in an electrical synapse, but most commonly occurs via the vesicular release of neurotransmitters from the presynaptic axon terminal into the synaptic cleft, as in a chemical synapse.

Many neurotransmitters are synthesized from simple and plentiful precursors such as amino acids, which are readily available from the diet and only require a small number of biosynthetic steps for conversion.

Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis.

Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological function in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus.

Immunocytochemical techniques have also revealed that many transmitters, particularly the neuropeptides, are co-localized, that is, one neuron may release more than one transmitter from its synaptic terminal.

Peptidergic neurons commonly express and synthesize multiple neuropeptides and also release other small-molecule neurotransmitters, but the co-release relationships are poorly understood.

It is a type of chemical messenger which transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell.

Glycine is also an inhibitory neurotransmitter - interference with its release within the spinal cord (such as during a Clostridium tetani infection) can cause spastic paralysis due to uninhibited muscle contraction.

In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace amine-associated receptor 1 (TAAR1) and inhibiting vesicular monoamine transporter 2 (VMAT2) in monoamine neurons; to a lesser extent, it also acts as a neurotransmitter in the human central nervous system.

In response to a threshold action potential or graded electrical potential, a neurotransmitter is released at the presynaptic terminal.

Depolarization of axon terminals, in general, triggers the release of neurotransmitter into the synaptic cleft.

Anandamide, also known as N-arachidonoylethanolamine (AEA), is a fatty acid neurotransmitter derived from the non-oxidative metabolism of eicosatetraenoic acid (arachidonic acid), an essential omega-6 fatty acid.

It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator.

L-phenylalanine and L-tyrosine are both precursors for dopamine, norepinephrine, and epinephrine.

Adrenaline is normally produced by both the adrenal glands and a small number of neurons in the medulla oblongata where it acts as a neurotransmitter involved in regulating visceral functions (e.g., respiration).

In many types of invertebrates octopamine is an important neurotransmitter and hormone.

Trace amines have a modulatory effect on neurotransmission in monoamine pathways (i.e., dopamine, norepinephrine, and serotonin pathways) throughout the brain via signaling through trace amine-associated receptor 1.

Although they can be synthesized within parent monoamine neurotransmitter systems, there is evidence that suggests that some of them may comprise their own independent neurotransmitter systems.

Kainate receptors, or kainic acid receptors (KARs), are ionotropic receptors that respond to the neurotransmitter glutamate.

Single ions (such as synaptically released zinc) are also considered neurotransmitters by some, as well as some gaseous molecules such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H 2 S).

Following the first report that carbon monoxide is a normal neurotransmitter in 1993, as well as one of three gases that naturally modulate inflammatory responses in the body (the other two being nitric oxide and hydrogen sulfide), carbon monoxide has received a great deal of clinical attention as a biological regulator.