View source for Chemistry:Alpha-2 blocker

{{Short description|Drugs blocking alpha-2 adrenergic receptors, limited clinical application in humans.}}
'''Alpha-2 blockers''' (or '''α<sub>2</sub> blockers''') are a subset of the [[Chemistry:Alpha blocker|alpha blocker]] class of drugs and are [[Biology:Receptor antagonist|antagonists]] to the [[Biology:Alpha-2 adrenergic receptor|α<sub>2</sub> adrenergic receptor]]. They are mainly used in research, having found limited clinical application in human medicine. Alpha-2 blockers increase noradrenaline release.

==Uses==

[[Chemistry:Yohimbine|Yohimbine]], historically used as an aphrodisiac, is sometimes used in veterinary medicine (although now largely replaced by [[Chemistry:Atipamezole|atipamezole]]) for reversing the effects of α<sub>2</sub>s such as [[Chemistry:Medetomidine|medetomidine]] that are used as sedatives during surgery.<ref>{{cite journal|last=Lemke|first=KA|title=Perioperative use of selective alpha-2 agonists and antagonists in small animals.|journal=The Canadian Veterinary Journal|date=June 2004|volume=45|issue=6|pages=475–80|pmid=15283516|pmc=548630}}</ref>

The tetracyclic antidepressants [[Chemistry:Mianserin|mianserin]] and [[Chemistry:Mirtazapine|mirtazapine]] are α<sub>2</sub> blockers, although their efficacy as antidepressants may come from their activity at other receptor sites.{{citation needed|date=June 2020}}

Mechanistically, α<sub>2</sub> blockers increase [[Biology:Adrenergic|adrenergic]], [[Chemistry:Dopaminergic|dopaminergic]] and [[Chemistry:Serotonin|serotonergic]] neurotransmitters and induce [[Biology:Insulin|insulin]] secretion, decreasing blood sugar levels.{{citation needed|date=June 2020}}

Withdrawal from α<sub>2</sub> blockers can be difficult or dangerous as the global downregulation of neurotransmitters may cause symptoms of depression and other neurological problems, and increased blood sugar levels together with decreased insulin sensitivity can cause diabetes.{{citation needed|date=June 2020}} Moreover, reduced [[Biology:Microcirculation|microcirculation]] together with adrenaline supersensitivity in organs such as liver can occur.{{citation needed|date=June 2020}}

==Examples==
Examples include [[Chemistry:Atipamezole|atipamezole]],<ref name="pmid14566451">{{cite journal |vauthors =Haapalinna A, Leino T, Heinonen E |title=The alpha 2-adrenoceptor antagonist atipamezole potentiates anti-Parkinsonian effects and can reduce the adverse cardiovascular effects of dopaminergic drugs in rats |journal=Naunyn Schmiedebergs Arch. Pharmacol. |volume=368 |issue=5 |pages=342–51 |date=November 2003 |pmid=14566451 |doi=10.1007/s00210-003-0827-z|s2cid=23897064 }}</ref> [[Chemistry:Efaroxan|efaroxan]], [[Chemistry:Idazoxan|idazoxan]],<ref name="pmid9918591">{{cite journal |vauthors =Chopin P, Colpaert FC, Marien M |title=Effects of alpha-2 adrenoceptor agonists and antagonists on circling behavior in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway |journal=J. Pharmacol. Exp. Ther. |volume=288 |issue=2 |pages=798–804 |date=February 1999 |pmid=9918591 |url=http://jpet.aspetjournals.org/cgi/pmidlookup?view=long&pmid=9918591}}</ref> [[Chemistry:Yohimbine|yohimbine]], and [[Chemistry:Rauwolscine|rauwolscine]], [[Chemistry:Phentolamine|phentolamine]].

==References==
{{reflist}}

==External links==

{{Alpha blockers}}
{{Receptor agonists and antagonists}}

{{DEFAULTSORT:Alpha-2 Blocker}}
[[Category:Alpha-2 blockers| ]]



{{Sourceattribution|Alpha-2 blocker}}