Clozapine N-oxide(CNO) is a potent dopamine antagonist and also a potent and selective muscarinic M4 receptor (EC50=11 nM) agonist[5，6].Clozapine N-oxide also is a major metabolite of Clozapine and a human muscarinic designer receptors (DREADDs) agonist[1,2]. Clozapine N-oxide activates the DREADD receptor hM3Dq and hM4Di. Clozapine N-oxide(CNO) is a pharmacologically inert molecule that lacks a significant (<1 μm) affinity for the receptor[3]. Clozapine N-oxide(CNO) is highly bioavailable in rodents and humans[4]
Clozapine N-oxide(CNO) significantly reduces the density of the 5-HT2 receptor in rat cortical cells, A significant decrease was found in primary cortical cells for 5-HT(2) receptor density and 5-HT(2A) receptor mRNA levels[7].
In both β-R-q and β-R-s Tg mice, Clozapine N-oxide(CNO) treatment resulted in a dose-dependent decrease in blood glucose levels and increased plasma insulin concentrations, demonstrating that the degree of β cell G protein signaling could be titrated according to the Clozapine N-oxide(CNO) dose administered[8].Oral Clozapine N-oxide(CNO) administration via drinking water to mice expressing rM3Dq in pancreatic β-cells led to robust metabolic phenotypes, indicating that significant amounts of Clozapine N-oxide(CNO) are absorbed from the gastrointestinal tract[9].It created transgenic mice expressing an evolved G protein-coupled receptor (hM3Dq) selectively activated by the pharmacologically inert, orally bioavailable drug Clozapine N-oxide (CNO).Local field potential and single-neuron recordings revealed that peripheral administration of Clozapine N-oxide(CNO) activated hippocampal neurons selectively in hM3Dq-expressing mice. Behavioral correlates of neuronal activation included increased locomotion, stereotypy, and limbic seizures[10].
References:
[1]: Wess J, Nakajima K, et,al. Novel designer receptors to probe GPCR signaling and physiology. Trends Pharmacol Sci. 2013 Jul;34(7):385-92. doi: 10.1016/j.tips.2013.04.006. Epub 2013 Jun 13. PMID: 23769625; PMCID: PMC3758874.
[2]: Manvich DF, Webster KA, et,al. The DREADD agonist clozapine N-oxide (CNO) is reverse-metabolized to clozapine and produces clozapine-like interoceptive stimulus effects in rats and mice. Sci Rep. 2018 Mar 1;8(1):3840. doi: 10.1038/s41598-018-22116-z. PMID: 29497149; PMCID: PMC5832819.
[3]: Weiner DM, Meltzer HY, et,al. The role of M1 muscarinic receptor agonism of N-desmethylclozapine in the unique clinical effects of clozapine. Psychopharmacology (Berl). 2004 Dec;177(1-2):207-16. doi: 10.1007/s00213-004-1940-5. Epub 2004 Jul 16. PMID: 15258717.
[4]: Bender D, Holschbach M, et,al. Synthesis of n.c.a. carbon-11 labelled clozapine and its major metabolite clozapine-N-oxide and comparison of their biodistribution in mice. Nucl Med Biol. 1994 Oct;21(7):921-5. doi: 10.1016/0969-8051(94)90080-9. PMID: 9234345.
[5]: Silva RR, Parreiras-E-Silva LT, et,al. Evaluation of Functional Selectivity of Haloperidol, Clozapine, and LASSBio-579, an Experimental Compound With Antipsychotic-Like Actions in Rodents, at G Protein and Arrestin Signaling Downstream of the Dopamine D2 Receptor. Front Pharmacol. 2019 Jun 4;10:628. doi: 10.3389/fphar.2019.00628. PMID: 31214037; PMCID: PMC6558205.
[6]: Zorn SH, Jones SB, et,al. Clozapine is a potent and selective muscarinic M4 receptor agonist. Eur J Pharmacol. 1994 Nov 15;269(3):R1-2. doi: 10.1016/0922-4106(94)90047-7. PMID: 7895765.
[7]: Heiser P, Schulte E, et,al. Effects of clozapine and its metabolites on the 5-HT2 receptor system in cortical and hippocampal cells in vitro. Prog Neuropsychopharmacol Biol Psychiatry. 2004 Mar;28(2):297-302. doi: 10.1016/j.pnpbp.2003.10.008. PMID: 14751426.
[8]: Guettier JM, Gautam D, et,al. A chemical-genetic approach to study G protein regulation of beta cell function in vivo. Proc Natl Acad Sci U S A. 2009 Nov 10;106(45):19197-202. doi: 10.1073/pnas.0906593106. Epub 2009 Oct 26. PMID: 19858481; PMCID: PMC2767362.
[9]: Jain S, Ruiz de Azua I, et,al. Chronic activation of a designer G(q)-coupled receptor improves β cell function. J Clin Invest. 2013 Apr;123(4):1750-62. doi: 10.1172/JCI66432. Epub 2013 Mar 8. PMID: 23478411; PMCID: PMC3613926.
[10]:Alexander GM, Rogan SC, et,al. Remote control of neuronal activity in transgenic mice expressing evolved G protein-coupled receptors. Neuron. 2009 Jul 16;63(1):27-39. doi: 10.1016/j.neuron.2009.06.014. PMID: 19607790; PMCID: PMC2751885.
Clozapine N-oxide（CNO）是一种强效的多巴胺拮抗剂,也是一种选择性肌动蛋白M4受体（EC50=11 nM）激动剂。Clozapine N-oxide还是氯氮平的主要代谢产物和人类肌动蛋白设计受体（DREADDs）激动剂。Clozapine N-oxide可以激活DREADD受体hM3Dq和hM4Di。Clozapine N-oxide（CNO）是一种药理学上惰性分子,缺乏对受体的显着亲和力(
Clozapine N-oxide（CNO）显著降低了大鼠皮层细胞中5-HT2受体的密度。在初级皮层细胞中发现5-HT(2)受体密度和5-HT(2A)受体mRNA水平明显下降[7]。
在β-R-q和β-R-s Tg小鼠中,克氏培南氧化物（CNO）治疗导致血糖水平降低和血浆胰岛素浓度增加,表明β细胞G蛋白信号的程度可以根据给予的CNO剂量进行调节。通过口服含有Clozapine N-oxide(CNO)的饮用水给表达rM3Dq的胰岛β细胞小鼠进行处理,产生了强大的代谢表型,这表明从肠道吸收了大量Clozapine N-oxide(CNO)。创建了转基因小鼠,它们表达一种进化后的G蛋白偶联受体（hM3Dq）,只能被药理学上惰性、口服可利用药物Clozapine N-oxide (CNO)激活。局部场电位和单个神经元记录显示,在hM3Dq表达小鼠中外周给予Clozapine N-oxide(CNO)会选择性地激活海马神经元。神经元激活行为相关包括运动增加、刻板行为和边缘癫痫发作。