• Archives of Pharmacal Research
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• 제17권6호
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• pp.443-451
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• 1994

The binding characteristics of pirenzepine and oxomemazine to muscarinic receptor were studied to evaluate the selectivity of oxomemazine for the muscarinic receptor subtypes in rat cerebral microsomes. Equililbrium dissociation constant $(K_D){\;}of{\;}(-)[^3H]$quinuclidinyl benzilate$([^3H)QNB)$ determined from saturation isotherms was 64-pM. Analysis of the pirenzepine inghibition curve of [$^3H$]QNB binding to cerebral microsome indicatd the presence of two receptor subtypes with high $(K_1 = 16 nM, M_1 receptor)$two receptor subypes with about 20-fold difference in the affinity for high $(k_1 = 84nM, {\;} O_H receptor){\;} and {\;}low{\;} (K_1{\;} ={\;} 1.65\muM, {\;} O_L receptor$) affinity sites. The percentage populations of $M_1{\;} and M_3$, /TEX> receptors to the total receptors were 61 : 39, and those of $O_H{\;} and{\;} O_L$ receptors 39 : 61, resepectively. Both pirenzepine and oxomemazine increaed the $K_D$ value for $[^3H]QNB$ without affecting the binding site concentrations and Hii coefficient for the $[^3H]QNB$ without affecting the binding site concentractions and Hill coefficient for the [$^{3}$H]QNB binding. Oxomemazine had a 10-fold higher affinity at $M_1$ receptors than at $M_3$ receptors, and pirenzepine a 8-fold higher affinity at $O_H$ receptors were of $O_H$ receptors and 71% of $M_3$ receptors. However, $M_3$for oxomemazine and $O_H$for pirenzepine were composed of a uniform population. These results suggest that oxomemazine could be classified as a selective drug for $M_1$ receptors and also demonstrate that rat cerebral microsomes contain three different subtypes of $M_1{\;} M_3$ and the other site which is different from $M_1, {\;} M_2$, /TEX> receptors.

• Molecules and Cells
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• 제39권4호
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• pp.322-329
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• 2016

Voltage-gated $Ca^{2+}$ ($Ca_V$) channels are dynamically modulated by Gprotein-coupled receptors (GPCR). The $M_1$ muscarinic receptor stimulation is known to enhance $Ca_V2.3$ channel gating through the activation of protein kinase C (PKC). Here, we found that $M_1$ receptors also inhibit $Ca_V2.3$ currents when the channels are fully activated by PKC. In whole-cell configuration, the application of phorbol 12-myristate 13-acetate (PMA), a PKC activator, potentiated $Ca_V2.3$ currents by ~two-fold. After the PMA-induced potentiation, stimulation of $M_1$ receptors decreased the $Ca_V2.3$ currents by $52{\pm}8%$. We examined whether the depletion of phosphatidylinositol 4,5-bisphosphate ($PI(4,5)P_2$) is responsible for the muscarinic suppression of $Ca_V2.3$ currents by using two methods: the Danio rerio voltage-sensing phosphatase (Dr-VSP) system and the rapamycin-induced translocatable pseudojanin (PJ) system. First, dephosphorylation of $PI(4,5)P_2$ to phosphatidylinositol 4-phosphate (PI(4)P) by Dr-VSP significantly suppressed $Ca_V2.3$ currents, by $53{\pm}3%$. Next, dephosphorylation of both PI(4)P and $PI(4,5)P_2$ to PI by PJ translocation further decreased the current by up to $66{\pm}3%$. The results suggest that $Ca_V2.3$ currents are modulated by the $M_1$ receptor in a dual mode-that is, potentiation through the activation of PKC and suppression by the depletion of membrane $PI(4,5)P_2$. Our results also suggest that there is rapid turnover between PI(4)P and $PI(4,5)P_2$ in the plasma membrane.

• Tuberculosis and Respiratory Diseases
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• 제49권4호
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• pp.486-494
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• 2000

연구배경 : 부교감 신경의 자극에 의해 유발된 기관지 수축은 $M_2$ 무스카린성 수용체(muscarinic receptors)에 의해 억제된다. 기관지 과민성을 유발시킨 동물 모델에서는 아세틸콜린 분비를 억제하는 $M_2$ 무스카린성 수용체 기능이 손상되어 아세틸콜린의 분비가 증가되고, 이로 인해 기관지 과민성을 나타낸다. 본 연구에서는 경증, 중등증, 중증 천식 환자를 대상으로 $M_2$ 무스카린성 수용체 기능 이상이 있는지 여부와 천식의 중증도에 따라 $M_2$ 무스카린성 수용체 기능에 차이가 있는지를 알아보고자 연구를 시행하였다. 대상 및 방법 : 고려대학교 안암병원 내과에서 천식으로 진단 받은 27명을 대상으로 하였다. 이 중 경증 천식이 11명, 중등증 천식이 8명, 중증 천식 8명이었다. 천식 발작이 있거나, 2주 이내에 상기도 감염이 있는 환자, 메타콜린 유발 검사에서 음성($PC_{20}{\geq}$16mg/ml)인 환자는 제외하였다. 대상 환자들은 메타콜린 유발 검사를 시행하여 $PC_{20}$을 구하고, 1주일 후에 $M_2$ 무스카린성 수용체 촉진제(agonist) 인 필로카핀(pilocarpine) $180{\mu}g$을 흡입한 후 1차 때와 같은 방법으로 $PC_{20}$을 구해 두 값을 비교하였다. 결과 : 대상 환자의 평균 연령은 39.3$\pm$12.3세였다. 천식의 중증도에 따라 결과를 분석해 보면 경증 천식 환자는 필로카핀 흡입 전 $PC_{20}$은 5.30$\pm$5.23mg/ml(평균$\pm$표준편차)에서 필로카핀 흡입 후 20.82$\pm$22.56mg/ml이었으며(p=0.004), 중등증 천식 환자는 필로카핀 흡입 전 $PC_{20}$은 2.79$\pm$1.51mg/ml에서 필로카핀 흡입 후 4.67$\pm$3.53mg/ml(p=0.012)로 유의하게 증가하였다. 이는 필로카핀에 대한 $M_2$ 무스카린성 수용체 기능이 정상임을 말해준다. 그러나 중증 천식 환자는 필로카핀 흡입 전 $PC_{20}$은 1.76$\pm$1.50mg/ml에서 필로카핀 흡입 후 3.18$\pm$4.03mg/ml(p=0.161)로 필로카핀 흡입 후에 통계적으로 유의한 차이가 없었다. 이는 중증 천식에서는$M_2$ 무스카린성 수용체 기능 이상이 있음을 말해준다. 결론 : 경증, 중등증, 중증을 대상으로 $M_2$ 무스카린성 수용체 기능을 조사해본 결과 경증과 중등증 천식에서는 $M_2$ 무스카린성 수용체 기능 이상이 없었고, 중증 천식에서는 $M_2$ 무스카린성 수용체 기능 이상이 있었다. 이는 천식의 중증도에 따라 $M_2$ 무스카린성 수용체 기능에 차이가 있음을 말해준다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권6호
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• pp.639-645
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• 1997

The purpose of the present study is to determine the role of muscarinic cholinergic receptors of posterior hypothalamus in the central blood pressure regulation when respiration is controlled. In anesthetized and artificially ventilated rats, vasodepressor response was evoked by injection of L-glutamate(10 nmol) neuroexcitatory amino acid into the posterior hypothalamic area. The injection of $carbachol(0.5{\sim}8\;nmol)$ into the same area induced dose-dependent vasodepressor and bradycardic responses. Pretreatment with atropine(4 nmol) completely blocked the vasodepressor response to carbachol(2 nmol). In contrast, in spontaneously breathing rats, the injection of carbachol(8 nmol) into the posterior hypothalamic area induced the vasopressor and tachycardic responses. These results suggest that the muscarinic cholinergic receptors in the posterior hypothalamic area primarily play an inhibitory role in the central regulation of blood pressure and heart rate.

• Biomolecules & Therapeutics
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• 제12권2호
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• pp.101-107
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• 2004

Repeated administration of psychostimulants such as amphetamines increases locomotor activity in rodents. These drugs, including methamphetamine, enhance dopaminergic neurotransmission and result in hyper-locomotion and behavioral sensitization. It is well known that the existence of a complex balance between the cholinergic and dopaminergic systems in the central nervous system. Thus, behavioral sensitization by methamphetamine may be related to the expression of the M1 muscarinic acetylcholine receptors gene. The present study investigated the changes of M1R mRNA in hyperlocomotor activity and behavioral sensitization by methamphetamine (2 mg/kg) in mice. Our results showed that M1R mRNA expression was increased in the frontal cortex and the hippocampus region (the CA2 region) in the acute methamphetamine administered group compared to the saline administered group. In the chronic group, M1R mRNA expression was increased in the frontal cortex ill1d the hippocampus regions (CA2 and DG regions) in melt1amphetamine administered group compared to saline control group. These results indicate that acute or chronic treatment of mathamphetamine leads to the region-specific changes in mRNA expression levels of M1R. Therefore, Therefore, the present result suggests that M1R may play a role in modulating of methamphetamine-induced behavioral sensitization in mice.

• Tuberculosis and Respiratory Diseases
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• 제70권5호
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• pp.384-389
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• 2011

The prevention of and the controlling of symptoms, reductions in the frequency of exacerbations, and disease severity are central to the pharmacologic therapy of chronic obstructive pulmonary disease (COPD). COPD patients are inclined to be older, have more comorbidities, and use polypharmacy as a result. Long-acting inhaled muscarinic antagonists (LAMAs) is a preferred treatment modality. However, the cardiovascular (CV) safety of anti-cholinergics, including LAMA, has been an issue. In contrast, the results of the UPLIFT trial and a pooled analysis of data from 30 trials of tiotropium illustrates the association of tiotropium with reductions in the risk of all cause mortality, CV mortality and CV events. And, the UPLIFT trial provides clues regarding the additive advantages of tiotropium in COPD patients who already are using long-acting inhaled ${\beta}_2$ agonists and inhaled corticosteroids. Following the contribution of tiotropium as a first LAMA, new LAMAs such as aclidinium and glycopyrrolate (NVA-237) seem to be emerging.

• 생약학회지
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• 제32권3호통권126호
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• pp.219-225
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• 2001

The water extracts of 82 Korean medicinal herbs were examined for the binding affinity on the recombinant human muscarinic acetylcholine receptor subtype 1 $(mAChR-M_1)$ produced from the CHO (Chinese Hamster Ovary) cell line. Of those tested, the extracts of Coptidis Rhizoma, Phellodendri Cortex, Hedyotis Herba and of Terminariae Fructus were found to exhibit a significant competition with $[^3H]$ N-methyl-scopolamine for the specific binding to $mAChR-M_1$ in a dose dependent manner, respectively.

• Molecules and Cells
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• 제25권4호
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• pp.504-509
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• 2008

Three G-protein-linked acetylcholine receptors (GARs) exist in the nematode C. elegans. GAR-3 is pharmacologically most similar to mammalian muscarinic acetylcholine receptors (mAChRs). We observed that carbachol stimulated ERK1/2 activation in Chinese hamster ovary (CHO) cells stably expressing GAR-3b, the predominant alternatively spliced isoform of GAR-3. This effect was substantially reduced by the phospholipase C (PLC) inhibitor U73122 and the protein kinase C (PKC) inhibitor GF109203X, implying that PLC and PKC are involved in this process. On the other hand, GAR-3b-mediated ERK1/2 activation was inhibited by treatment with forskolin, an adenylate cyclase (AC) activator. This inhibitory effect was blocked by H89, an inhibitor of cAMP-dependent protein kinase A (PKA). These results suggest that GAR-3b-mediated ERK1/2 activation is negatively regulated by cAMP through PKA. Together our data show that GAR-3b mediates ERK1/2 activation in CHO cells and that GAR-3b can couple to both stimulatory and inhibitory pathways to modulate ERK1/2.

• 약학회지
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• 제39권6호
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• pp.645-653
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• 1995

Dibenamine inhibited [$^{3}$H]quinuclidinyl benzilate ([$^{3}$H]QNB) binding in both concentration and incubation time-dependent manners. The $IC_{50}$/ value of dibenamine for the inhibition of the specific binding of 100 pM [$^{3}$'H]QNB following incubation of cerebral microsomes with dibenamine at 37.deg. C for 15 min was 20.mu.M. Dibenamine irreversibly decreased the binding site concentration for [$^{3}$H]QNB binding without affecting the affinity of [$^{3}$H]QNB for the muscarinic receptor. Analysis of the pirenzepine inhibition curve of [$^{3}$H]QNB binding to cerebral microsomes indicated the presence of two receptor subtypes with high(M$_{1}$ receptor, Ki=5nM) and low (M$_{2}$ receptor, Ki=160nM) affinity for pirenzepine. However, dibenamine(20.mu.M) treatment under the condition employed in these experiments caused steepening of the pirenzepine competition curve. The Ki value for pirenzepine in dibenamine treated-microsomes was approximately 120nM. suggesting a selective decrease in the number of M$_{1}$ receptor. Although dibenamine also inhibited [$^{3}$H]QNB binding to ventricular microsomes with $IC_{50}$/ value of 120.mu.M, the sensitivity for dibenamine in the ventricle was much lower than that in the cerebrum. These results indicate that dibenamine at low concentrations welectively inactivates the muscarinic M$_{1}$ receptor.

• International Journal of Oral Biology
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• 제44권2호
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• pp.62-70
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• 2019

Xylitol is well-known to have an anti-caries effect by inhibiting the replication of cariogenic bacteria. In addition, xylitol enhances saliva secretion. However, the precise molecular mechanism of xylitol on saliva secretion is yet to be elucidated. Thus, in this study, we aimed to investigate the stimulatory effect of xylitol on saliva secretion and to further evaluate the involvement of xylitol in muscarinic type 3 receptor (M3R) signaling. For determining these effects, we measured the saliva flow rate following xylitol treatment in healthy individuals and patients with dry mouth. We further tested the effects of xylitol on M3R signaling in human salivary gland (HSG) cells using real-time quantitative reverse-transcriptase polymerase chain reaction, immunoblotting, and immunostaining. Xylitol candy significantly increased the salivary flow rate and intracellular calcium release in HSG cells via the M3R signaling pathway. In addition, the expressions of M3R and aquaporin 5 were induced by xylitol treatment. Lastly, we investigated the distribution of M3R and aquaporin 5 in HSG cells. Xylitol was found to activate M3R, thereby inducing increases in $Ca^{2+}$ concentration. Stimulation of the muscarinic receptor induced by xylitol activated the internalization of M3R and subsequent trafficking of aquaporin 5. Taken together, these findings suggest a molecular mechanism for secretory effects of xylitol on salivary epithelial cells.