“Alpha-2 blocker”的意思、由来-开放百科全书

α₂-blockers are a subset of the alpha blocker class of drugs and are antagonists to the α₂ adrenergic receptor. They are mainly used in research, finding limited clinical application in human medicine. Increases the noradrenaline release due to blockade of alpha-2 receptors.

Uses

Historically, yohimbine was used as an aphrodisiac, and is still sometimes used in veterinary medicine (although now largely replaced by atipamezole) for reversing the effects of alpha-2 agonists such as medetomidine which are used as sedatives during surgery.^[1]

α₂-blockers have found medical uses in treating depression; the tetracyclic antidepressants mianserin and mirtazapine are α₂-blockers, although their efficacy as antidepressants may come from their activity at other receptor sites.

Mechanistically, α₂-blockers significantly increase adrenergic, dopaminergic and serotonergic neurotransmitters, and induce insulin secretion and decreases blood sugar levels.

Withdrawal from α₂-blockers can be difficult or dangerous as the global down regulation of neurotransmitters may cause symptoms of depression and other neurological problems, and increased blood sugar levels together with decreased insulin sensitivity can cause diabetes. Reduced microcirculation together with adrenaline supersensitivity in organs such as liver can also be difficult problem when withdrawing from adrenergic blockers.

Examples

Examples include atipamezole,^[2] efaroxan, idazoxan,^[3] yohimbine, and rauwolscine, Phentolamine.

References

1. ^{{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}}
2. ^{{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}}
3. ^{{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 |doi= |url=http://jpet.aspetjournals.org/cgi/pmidlookup?view=long&pmid=9918591}}