noradrenergic system

Noradrenergic system

A neuronal system that is responsible for the synthesis, storage, and release of the neurotransmitter norepinephrine. Norepinephrine, also known as noradrenalin, consists of a single amine group and a catechol nucleus (a benzene ring with two hydroxyl groups) and is therefore referred to as a monoamine or catecholamine. It exists in both the central and peripheral nervous systems. Norepinephrine is the primary neurotransmitter released by the sympathetic nervous system, which mediates the “fight or flight” reaction, preparing the body for action by affecting cardiovascular function, gastrointestinal motility and secretion, bronchiole dilation, glucose metabolism, and so on. Within the central nervous system, norepinephrine has been associated with several brain functions, including sleep, memory, learning, and emotions.

After synthesis, the majority of norepinephrine is transported into synaptic vesicles in the nerve terminals, where it remains until needed. When the nerve terminal is activated by depolarization, calcium flows into it, leading to the release of norepinephrine into the synaptic cleft. Once released into the synaptic cleft, norepinephrine is free to bind to specific receptors located on the presynaptic or postsynaptic terminal, which initiates a chain of events (the effector system) in the target cell that can be mediated by a number of different second messenger systems. The exact effect is determined by the identity of the receptor activated. See Epinephrine, Second messenger, Sympathetic nervous system, Synaptic transmission

Termination of norepinephrine occurs by a reuptake mechanism in the presynaptic membrane. Once transported back into the presynaptic terminal, norepinephrine can be stored in vesicles for future use or enzymatically degraded by monoamine oxidase.

Certain medications achieve their effect by altering various stages of synthesis, storage, release, and inactivation of norepinephrine. The behavioral manifestations of these alterations have led to a better understanding of norepinephrine's role in various psychiatric disorders. See Affective disorders, Monoamine oxidase, Psychopharmacology, Schizophrenia, Stress

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

noradrenergic system

[nȯr¦ad·rə¦nər·jik ′sis·təm]
(neuroscience)
A system of neurons that is responsible for the synthesis, storage, and release of the neurotransmitter norepinephrine.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Antidepressant-like effect of tramadol in the unpredictable chronic mild stress procedure: Possible involvement of the noradrenergic system. Behav Pharmacol 2007;18:623-31.
Attention and emotion have a positive impact on memory formation, which is related to the activation of the noradrenergic system in the brain (1,2).
(12) More recent attention has focused on the importance of the role of brain stress systems in both drinking behavior (13) and PTSD symptomology, (14) highlighting the importance of the noradrenergic system. "Feed-forward" mechanisms within the stress systems may mediate exaggerated stress responses in individuals with AUD and PTSD.
The involvement of noradrenergic system in nociception at spinal and supraspinal levels has been proven to be mediated through activation of [alpha]-adrenoceptors and descending inhibitory pathways [56].
Gokul, "Evaluation of role of noradrenergic system in the antidepressant activity of tramadol using tail suspension test in Albino mice," Journal of Pharmacology and Pharmacotherapeutics, vol.
Interestingly, animals treated with vitexin exhibited a significant increase in the time spent climbing in the forced swim test [53], suggesting that activation of the noradrenergic system maybe involved in the antidepressant-like effect of this flavonoid.
An interaction with the central noradrenergic system is one of the possible routes, and the main premise is that salsolinol suppresses TH activity [117, 118].
The noradrenergic system is responsible for the synthesis, storage, and release of norepinephrine.
These include the cholinergic system (nucleus basasils of Meynert), the serotonergic system, and the noradrenergic system (Jellinger, 1999).
Voiding function is provided by the inhibitory effect of some neurotransmitters, such as glycine, gamma-aminobutyric acid (GABA) opioids, purines, and the noradrenergic system at various levels of the neural axis.
It has been proposed that alterations in the activity of Th in the central noradrenergic system may lead to depression [58].
(14) also demonstrated the role of the noradrenergic system in the nociceptive effect of mirtazapine, in addition to the opioidergic and serotoninergic systems.