The alpha-2A adrenergic receptor (α_2A adrenoceptor), also known as ADRA2A, is an α₂ adrenergic receptor, and also denotes the human gene encoding it.

Receptor

α₂ adrenergic receptors include 3 highly homologous subtypes: α_2A, α_2B, and α_2C. These receptors have a critical role in regulating

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neuro ...

release from

sympathetic nerves The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the ...

and from adrenergic neurons in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

. Studies in mice revealed that both the α_2A and α_2C subtypes were required for normal presynaptic control of transmitter release from sympathetic nerves in the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

and from central noradrenergic neurons; the α_2A subtype inhibited transmitter release at high stimulation frequencies, whereas the α_2C subtype modulated neurotransmission at lower levels of nerve activity

Gene

This gene encodes α_2A subtype and it contains no introns in either its coding or untranslated sequences.

Role in central nervous system

Although the pre-synaptic functions of α_2A receptors are often a major focus, the majority of α₂ receptors in the brain are actually localized post-synaptically to noradrenergic terminals, and therefore aid in the function of

norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...

. Many post-synaptic α_2A receptors have important effects on brain function; for example, α_2A receptors are localized on prefrontal cortical neurons where they regulate higher cognitive function .

Ligands

Agonists

4-NEMD 4-NEMD is a potent sedative drug which acts as a selective alpha-2 adrenergic agonist. It is closely related to dexmedetomidine but is several times more potent. Like other alpha-2 agonists, it produces sedative and muscle relaxant A muscle rel ...

Brimonidine Brimonidine is a medication used to treat open-angle glaucoma, ocular hypertension, and rosacea. In rosacea it improves the redness. It is used as eye drops or applied to the skin. Common side effects when used in the eyes include itchiness, re ...

Clonidine Clonidine, sold under the brand name Catapres among others, is an α2-adrenergic agonist medication used to treat high blood pressure, ADHD, drug withdrawal ( alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and c ...

* Dexmedetomidine * Guanfacine * Lofexidine *

Myrcene Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from '' Myrcia'', from which it gets its name. It is an intermediate in the production of several fragrances. � ...

* Medetomidine *

PS75 PS75 is an experimental analgesic drug which acts as a functionally selective alpha-2A adrenergic agonist, with a Ki of 8.2nM and an EC50 of 4.8nM at the α2A receptor. In animal studies it was found to produce analgesia but without the sedation ...

* Tizanidine *

Xylazine Xylazine is a pharmaceutical drug used for sedation, anesthesia, muscle relaxation, and analgesia in animals such as horses, cattle, and other non-human mammals. Veterinarians also use xylazine as an emetic, especially in cats. It is an analog o ...

Antagonists

* Idazoxan *

1-PP 1-(2-Pyrimidinyl)piperazine (1-PP, 1-PmP) is a chemical compound and piperazine derivative. It is known to act as an antagonist of the α2-adrenergic receptor (Ki = 7.3–40 nM) and, to a much lesser extent, as a partial agonist of the 5- ...

(active metabolite of buspirone and gepirone) * Asenapine *

BRL-44408 BRL-44408 is a drug used in scientific research which acts as a selective antagonist for the α2A adrenoreceptor. It has been suggested as having potential therapeutic application in the treatment of extrapyramidal side effects produced by som ...

* Clozapine * Lurasidone *

Mianserin Mianserin, sold under the brand name Tolvon among others, is an atypical antidepressant that is used primarily in the treatment of depression in Europe and elsewhere in the world. It is a tetracyclic antidepressant (TeCA). Mianserin is closely ...

Mirtazapine Mirtazapine, sold under the brand name Remeron amongst others, is an atypical antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks, but can also manifest as early as one to two weeks. It is o ...

Paliperidone Paliperidone, sold under the trade name Invega among others, is an atypical antipsychotic. It is mainly used to treat schizophrenia and schizoaffective disorder. It is marketed by Janssen Pharmaceuticals. An extended release formulation is a ...

* Risperidone * Yohimbine

References

External links

* * *