多巴胺受體D2(Dopamine receptor D2,簡稱D2R),為轉譯自 DRD2 基因的一種多巴胺受體蛋白。D2R最早於1975年為Philip Seeman所發現,並將其命名為「抗精神疾患性多巴胺受體」(antipsychotic dopamine receptor)[8]。D2R為所有抗精神病藥物的作用標的。
功能
D2R屬於一種多巴胺受體,並會與Gi結合。Gi為G蛋白偶聯受體的一種亞型,會抑制腺苷酸環化酶的活性[9]。
在小鼠模式中,齒狀回的neuronal calcium sensor-1(NCS-1)會影響D2R在細胞膜的表現量。這項機制會影響突觸可塑性及記憶形成[10]。
同型體
長形式(D2Lh)具有"規範"的序列,並作為經典突觸後蛋白發揮作用。[13]短形式(D2Sh)在突觸前作為調節突觸間隙中多巴胺水平的自身受體發揮作用。[13]D2Sh受體激動時抑制多巴胺釋放,拮抗時增加多巴胺釋放。[13]第三種D2(更長)的形式不同於270V被VVQ取代的規範序列。[14]
基因組
等位基因變異:
- A-241G
- C132T、G423A、T765C、C939T、C957T,以及G1101A[15]
- Cys311Ser
- -141C insertion/deletion[16]The polymorphisms have been investigated with respect to association with schizophrenia.[17]
Some researchers have previously associated the polymorphism Taq 1A (rs1800497) to the DRD2 gene. However, the polymorphism resides in exon 8 of the ANKK1 gene.[18]DRD2 TaqIA polymorphism has been reported to be associated with an increased risk for developing motor fluctuations but not hallucinations in Parkinson's disease.[19][20]
配體
大多數較老的抗精神病藥如氯丙嗪或氟哌啶醇是多巴胺D2受體的非選擇性拮抗劑,最多僅對"D2樣家族"受體具有選擇性,因此與D2、D3、D4以及許多其他受體都可以結合,例如血清素和組織胺受體,導致一系列副作用使得它們不適合科學研究。類似,用於治療柏金遜症的較舊的多巴胺促效劑例如溴隱亭和卡麥角林,對一種多巴胺受體的選擇性較差,儘管這些藥物中大多數確實能起到D2促效劑的作用,但它們也會影響其他多巴胺受體,亞型也是。現今有幾種選擇性D2配體 (生物化學)可以使用,並且隨着進一步的研究,這個數字可能會增加。
- 溴隱亭(Bromocriptine):完全受體致活劑
- Cabergoline(Caberl)
- N,N-Propyldihydrexidine:D1/D5受體制活劑dihydrexidine的類似物,對節後神經元的D2R親和性比節前神經元的D2自體受器高。
- Piribedil:同時也是 D3 受體致活劑及腎上腺素α2受體拮抗劑
- Pramipexole:同時也是D3、D4受體致活劑
- Quinelorane:affinity for D2 > D3
- Quinpirole:同時也是D3受體致活劑
- Ropinirole:完全受體致活劑
- Sumanirole:高選擇性完全受體致活劑
- Talipexole:對D2的親和性高於其他的多巴胺受體,但同時也是腎上腺素α2受體制活劑及5-HT3受體拮抗劑。
- Aplindore
- 阿立哌唑(Aripiprazole,在美國合法)[21]
- Brexpiprazole/OPC-34712
- Cariprazine
- RP5063
- GSK-789,472 – Also D3 antagonist, with good selectivity over other receptors [22]
- 氯胺酮(Ketamine,同時也為NMDA受體拮抗劑)
- LSD – in vitro, LSD was found to be a partial agonist and potentiates dopamine-mediated prolactin secretion in lactotrophs.[23]LSD is also a 5-HT2A agonist.
- 莫達非尼(Modafinil)
- Roxindole (only at the D2 autoreceptors)
- OSU-6162:亦為5-HT2A部分受體致活劑,acts as "dopamine stabilizer"
- Salvinorin A:亦為κ-鴉片類受體致活劑。
- Atypical antipsychotics
- Desmethoxyfallypride
- Domperidone – D2 and D3 antagonist; does not cross the blood-brain barrier
- Eticlopride
- Fallypride
- Hydroxyzine (Vistaril, Atarax)
- Itopride
- L-741,626 – highly selective D2 antagonist
- C11 Raclopride radiolabled – commonly employed in positron emission tomography studies[24]
- Typical antipsychotics
- SV 293[25]
- Yohimbine
- D2sh selective (presynaptic autoreceptors)
- 參見參考文獻[31]。
Protein–protein interactions
The D2 receptor forms receptor heterodimers in vivo (in living animals) with other G protein-coupled receptors; these include:[35]
- D1–D2 dopamine receptor heteromer
- D2–adenosine A2A
- D2–ghrelin receptor
- D2sh–TAAR1[note 1]
The D2 receptor has been shown to form hetorodimers in vitro (and possibly in vivo) with DRD3,[38]DRD5,[39]and 5-HT2A.[40]
註釋
參考文獻
外部連結
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