Receptorium adrenergicum alpha 2

Receptorium adrenergicum α₂ est simul grex quattuor receptoriorum neurotransmissoris adrenergicorum et receptoriorum proteino G copulatorum. Neurotransmissores stimulantes sunt noradrenalinum et adrenalinum principales, atque nonnullae aliae agonistae notae sunt^[1].

Cave: notitiae huius paginae nec praescriptiones nec consilia medica sunt.

Receptoria α2 Exemplum: ADRA2A
Alia nomina	ADRAR
Locus geni (homo)
Chromosoma	10 (humanum)
Locus	10q25.2 (homo)
Fontes externae	OMIM: 104210

De diversis subtypis receptoriorum α₂ iam relata sunt, ut α_2A, α_2B, α_2C. Non in mammaliis invenitur α_2D. Distributio subtyporum in corpore diversa est.

Effectus agonistarum α₂ possunt esse sedatio, analgesia, vasodilatatio, bradycardia.

Physiologia

Receptorium adrenergicum α₂ (RAα2) est superfamiliae receptoriorum proteino G copulatorum membrum. Neurotransmissores, qui in receptorium α₂ incidunt, sunt noradrenalinum (cum affinitate maiore α receptoriorum) et adrenalinum (cum affinitate maiore β receptoriorum). In corporis organis diversorum munerum agunt.

In cortice praefrontali cerebri RAα2 cognitioni servant. Receptoria α₂ momentum etiam gubernationis pressionis sanguinis habent^[2].

Inveniuntur

• receptorium α_2A (RAα2A) in cerebri loco caeruleo, mesencephalo, hypothalamo, hippocampo, medulla spinali, corticibus, cerebello, nucleis septalibus,
• receptorium α_2B (RAα2B) in systemate olfactorio, thalamo, stratum pyramidalis hippocampi,
• receptorium α_2C (RAα2C) in mesencephalo, corpore amygdaloide, systemate olfactorio, substantia nigra, nucleis basalibus. Occurrunt receptoria α_2C imprimis intra cellulas^[3], tantum ad temperaturas physiologicas^[4].

De systemate excitante reticulari ascendente et noradrenalino neurotransmissore

Conferatur pagina principalis Systema excitans reticulare ascendens.

Receptoria proteino G copulata

Conferatur pagina principalis Receptorium proteino G copulatum.

Receptoria proteino G copulata (RPGC) in genere, cum stimulata, signa per proteina GTP (guanosinum triphosphatum) ligantia (proteina G dicta) transmittunt. Receptoriis subunitates helicales septem sunt, quibus membranam cellularem transgreditur. Receptoria α₂ in endothelio vasorum sanguineorum diversorum reperiuntur, quo ea effectus suos per proteinum G inhibens (G_i) et postea per oxidasem acidi nitrici, cum formatione acidi nitrici (NO), ita vasodilatationem permittens, exercent^[5].

Cognitio et corticis praefrontalis receptoria α₂

Una cum receptoriis α₁ (RAα1) etiam receptoria α₂ (RAα2) in cortice praefrontali ad cognitionem referunt^[6]. Videtur, ut methylophenidatum, medicamentum tractationis conturbationis hypercineticae cum attentionis defecto (CHAD), in parte effectus emendativos ope RAα2 perficit^[7].

Munera receptoriorum α₂ pressionis fluxusque sanguinis

Receptoria adrenergica α₂ (RAα2) inveniuntur in cerebro, corde, renibus, vasibus sanguineis. Centralia RAα2A centrorum cerebralium pressionem sanguinis et in sanguine multitudinem noradrenalini minuit, peripherica RAα2B retentionem natrii et vasoconstrictionem perficit, peripherica quoque RAα2C vasoconstrictionem frigore inductam causat^[8].

Pathophysiologia

Polymorphismi receptoriorum α₂ significatio morborum cardiovascularium habent^[9].

Neurotransmissores stimulantes

• 
  Noradrenalinum

Agonistae receptoriorum α2

Agonistae α₂ sunt substantiae, quae receptoriis α₂ cellulas stimulant. Effectus earum possunt esse sedatio, analgesia, vasodilatatio, bradycardia^[10]. Exempla sunt:

• Clonidinum — hypertensionis arterialis, delirii trementis^[11]
• Dexmedetomidinum^[12]
• Mirtazapinum — obsidio receptoriorum H₁, α_2A, α_2C.

Antagonista receptoriorum α2

• Guanfacinum — receptoria α_2A incitat. Praeterea in CHAD tractando adhibentur^[13].

Notae

1. Knaus A. E., Muthig V., et al. (Oct 2007). "Alpha2-adrenoceptor subtypes--unexpected functions for receptors and ligands derived from gene-targeted mouse models". Neurochemistry international 51 (5): 277-81 
2. Che P., Chen Y., et al. (Aug 2015). "Spinophilin Is Indispensable for the α2B Adrenergic Receptor-Elicited Hypertensive Response". PLoS One 10 (8): e0135030  vel fluxus
3. Hurt C. M., Feng F. Y., Kobilka B. (Nov 2000). "Cell-type specific targeting of the alpha 2c-adrenoceptor. Evidence for the organization of receptor microdomains during neuronal differentiation of PC12 cells". The journal of biological chemistry 275 (45): 35424-31 
4. Filipeanu C. M., Pullikuth A. K., Guidry J. J. (Mai 2015). "Molecular determinants of the human α2C-adrenergic receptor temperature-sensitive intracellular traffic". Molecular pharmacology 87 (5): 792-802 
5. Vanhoutte P. M. (Nov 2001). "Endothelial adrenoceptors". Journal of cardiovascular pharmacology 38 (5): 7096-808 
6. Berridge C. W., Spencer R. C. (Iun 2016). "Differential cognitive actions of norepinephrine a2 and a1 receptor signaling in the prefrontal cortex". Brain research 1641 (Pt B): 189-96 
7. Arnsten A. F., Dudley A. G. (Apr 2005). "Methylphenidate improves prefrontal cortical cognitive function through alpha2 adrenoceptor and dopamine D1 receptor actions: Relevance to therapeutic effects in Attention Deficit Hyperactivity Disorder". Behavioral and brain functions 1 (1): 2 
8. Kanagy N. L. (Nov 2005). "Alpha(2)-adrenergic receptor signalling in hypertension". Clinical science 109 (5): 431-7 
9. Flordellis C., Manolis A., et al. (Dec 2004). "Clinical and pharmacological significance of alpha2-adrenoceptor polymorphisms in cardiovascular diseases". International journal of cardiology 97 (3): 367-72 
10. Nguyen V., Tiemann D., et al. (Iun 2017). "Alpha-2 Agonists". Anesthesiology clinics 35 (2): 233-45 
11. Muzyk A. J., Fowler J. A., et al. (Mai 2011). "Role of α2-agonists in the treatment of acute alcohol withdrawal". The annals of pharmacotherapy 45 (5): 649-57 
12. Mantz J., Josserand J., Hamada S. (Ian 2011). "Dexmedetomidine: new insights". European journal of anaesthesiology 28 (1): 3-6 
13. Alamo C., López-Muñoz F., Sánchez-García J. (Mai 2016). "Mechanism of action of guanfacine: a postsynaptic differential approach to the treatment of attention deficit hyperactivity disorder (adhd)". Actas espanolas de psiquiatria 44 (3): 107-12 

Nexus interni

• Receptorium adrenergicum alpha-1