E3 ligase carboxyl-terminus of Hsp70-interacting protein (CHIP) suppresses fibrotic properties in oral mucosa.

BACKGROUND/PURPOSE: Oral submucous fibrosis (OSF) represents a precancerous lesion of oral mucosa that may progress into oral cancer and its major etiological factor is areca nut chewing. Carboxyl-terminus of Hsp70-interacting protein (CHIP) functions as an ubiquitin E3 ligase and is associated with fibrosis diseases. In the current study, we sought to investigate whether CHIP participated in the areca nut-mediated OSF development. METHODS: The mRNA expression of CHIP in arecoline-stimulated buccal mucosal fibroblasts (BMFs) and OSF tissues was determined by qRT-PCR. Collagen gel contraction, migration and invasion assays were carried out to evaluate the myofibroblast activation. The protein expression levels of α-SMA and transglutaminase 2 (TGM2) were assessed by Western blot. RESULTS: The expression level of CHIP was reduced in BMFs following arecoline treatment in a dose-dependent manner, which was consistent with the observation of lower CHIP expression in OSF specimen compared to the normal counterparts. Ectopic expression of CHIP mitigated the myofibroblast activities, including elevated collagen gel contractility and cell motility. In addition, we showed that overexpression of CHIP downregulated the α-SMA and TGM-2 expression, which may lead to less fibrosis alteration. CONCLUSION: CHIP may not only function as a key regulator of protein quality control but also a critical deciding factor to oral fibrogenesis. Our findings suggested that CHIP possesses the anti-fibrotic effect, which may be mediated by TGM2 regulation. Restoration of CHIP could be a therapeutic direction to help OSF patients.

The Combination of the M2 Muscarinic Receptor Agonist and Chemotherapy Affects Drug Resistance in Neuroblastoma Cells.

One of the major limits of chemotherapy is depending on the ability of the cancer cells to elude and adapt to different drugs. Recently, we demonstrated how the activation of the M2 muscarinic receptor could impair neuroblastoma cell proliferation. In the present paper, we investigate the possible effects mediated by the preferential M2 receptor agonist arecaidine propargyl ester (APE) on drug resistance in two neuroblastoma cell lines, SK-N-BE and SK-N-BE(2C), a sub-clone presenting drug resistance. In both cell lines, we compare the expression of the M2 receptor and the effects mediated by the M2 agonist APE on cell cycle, demonstrating a decreased percentage of cells in S phase and an accumulation of SK-N-BE cells in G1 phase, while the APE treatment of SK-N-BE(2C) cells induced a block in G2/M phase. The withdrawal of the M2 agonist from the medium shows that only the SK-N-BE(2C) cells are able to rescue cell proliferation. Further, we demonstrate that the co-treatment of low doses of APE with doxorubicin or cisplatin significantly counteracts cell proliferation when compared with the single treatment. Analysis of the expression of ATP-binding cassette (ABC) efflux pumps demonstrates the ability of the M2 agonist to downregulate their expression and that this negative modulation may be dependent on N-MYC decreased expression induced by the M2 agonist. Our data demonstrate that the combined effect of low doses of conventional drugs and the M2 agonist may represent a new promising therapeutic approach in neuroblastoma treatment, in light of its significant impact on drug resistance and the possible reduction in the side effects caused by high doses of chemotherapy drugs.

Arecoline Alters Taste Bud Cell Morphology, Reduces Body Weight, and Induces Behavioral Preference Changes in Gustatory Discrimination in C57BL/6 Mice.

Arecoline, a major alkaloid in areca nuts, is involved in the pathogenesis of oral diseases. Mammalian taste buds are the structural unit for detecting taste stimuli in the oral cavity. The effects of arecoline on taste bud morphology are poorly understood. Arecoline was injected intraperitoneally (IP) into C57BL/6 mice twice daily for 1-4 weeks. After arecoline treatment, the vallate papillae were processed for electron microscopy and immunohistochemistry analysis of taste receptor proteins (T1R2, T1R3, T1R1, and T2R) and taste associated proteins (α-gustducin, PLCß2, and SNAP25). Body weight, food intake and water consumption were recorded. A 2-bottle preference test was also performed. The results demonstrated that 1) arecoline treatment didn't change the number and size of the taste buds or taste bud cells, 2) electron microscopy revealed the change of organelles and the accumulation of autophagosomes in type II cells, 3) immunohistochemistry demonstrated a decrease of taste receptor T1R2- and T1R3-expressing cells, 4) the body weight and food intake were markedly reduced, and 5) the sweet preference behavior was reduced. We concluded that the long-term injection of arecoline alters the morphology of type II taste bud cells, retards the growth of mice, and affects discrimination competencies for sweet tastants.

ZEB1 as an indicator of tumor recurrence for areca quid chewing-associated oral squamous cell carcinomas.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is the sixth most prevalent malignancy worldwide and the third most common cancer in developing nation. Most OSCC patients relapse within months after receiving treatment. Therefore, searching the biomarkers of recurrence is urgently required to improve OSCC patient survival. METHODS: We set out to explore whether expression of ZEB1 could be triggered in oral epithelial cells (SG and FaDu) by arecoline in vitro. Control and ZEB1-knockdown arecoline-stimulated SG and FaDu were subjected to migration/invasiveness/anchorage-independent growth assay. Primary and recurrent OSCC tissues from areca quid chewers were analyzed using real-time RT-PCR analysis for ZEB1 expression. RESULTS: Arecoline led to dose-dependent elevation of ZEB1 expression in SG and FaDu cells. Downregulation of ZEB1 by lentiviral infection significantly reversed arecoline-induced oncogenicity including migration ability, cell invasiveness, and anchorage-independent growth in SG and FaDu cells. Clinically, the level of ZEB1 expression was higher in recurrent OSCC tumor samples but lower in primary lesions. CONCLUSIONS: Targeting ZEB1 might offer a new strategy for the treatment of OSCC patients. ZEB1 can serve as a progression and relapse marker in OSCC patients.

Arecoline-induced myofibroblast transdifferentiation from human buccal mucosal fibroblasts is mediated by ZEB1.

Oral submucous fibrosis (OSF) is considered as a pre-cancerous condition of the oral mucosa and is highly associated with habitual areca quid chewing. Arecoline is the major alkaloid in areca quid and is thought to be involved in the pathogenesis of OSF. Our previous studies have demonstrated that arecoline could induce epithelial-mesenchymal transition (EMT)-related factors in primary human buccal mucosal fibroblasts (BMFs). Therefore, we investigated the expression of zinc finger E-box binding homeobox 1 (ZEB1), which is a well-known transcriptional factor in EMT, in OSF tissues and its role in arecoline-induced myofibroblast transdifferentiation from BMFs. The expression of ZEB1, as well as the myofibroblast marker α-smooth muscle actin (α-SMA), was significantly increased in OSF tissues, respectively. With immunofluorescence analysis, arecoline induced the formation of α-SMA-positive stress fibres in BMFs expressing nuclear ZEB1. Arecoline also induced collagen contraction of BMFs in vitro. By chromatin immunoprecipitation, the binding of ZEB1 to the α-SMA promoter in BMFs was increased by arecoline. The promoter activity of α-SMA in BMFs was also induced by arecoline, while knockdown of ZEB1 abolished arecoline-induced α-SMA promoter activity and collagen contraction of BMFs. Long-term exposure of BMFs to arecoline induced the expression of fibrogenic genes and ZEB1. Silencing of ZEB1 in fibrotic BMFs from an OSF patient also suppressed the expression of α-SMA and myofibroblast activity. Inhibition of insulin-like growth factor receptor-1 could suppress arecoline-induced ZEB1 activation in BMFs. Our data suggest that ZEB1 may participate in the pathogenesis of areca quid-associated OSF by activating the α-SMA promoter and inducing myofibroblast transdifferentiation from BMFs.

M2 receptors exert analgesic action on DRG sensory neurons by negatively modulating VR1 activity.

The peripheral application of the M2 cholinergic agonist arecaidine on sensory nerve endings shows anti-nociceptive properties. In this work, we analyze in vitro, the mechanisms downstream M2 receptor activation causing the analgesic effects, and in vivo the effects produced by M2 agonist arecaidine administration on nociceptive responses in a murine model of nerve growth factor (NGF)-induced pain. Cultured DRG neurons treated with arecaidine showed a decreased level of VR1 and SP transcripts. Conversely, we found an increased expression of VR1 and SP transcripts in DRG from M2/M4(-/-) mice compared to WT and M1(-/-) mice, confirming the inhibitory effect in particular of M2 receptors on SP and VR1 expression. Patch-clamp experiments in the whole-cell configuration showed that arecaidine treatment caused a reduction of the fraction of capsaicin-responsive cells, without altering the mean capsaicin-activated current in responsive cells. We also demonstrated that arecaidine prevents PKCϵ translocation to the plasma membrane after inflammatory agent stimulation, mainly in medium-small sensory neurons. Finally, in mice, we have observed that intraperitoneal injection of arecaidine reduces VR1 expression blocking hyperalgesia and allodynia caused by NGF intraplantar administration. In conclusion, our data demonstrate that in vivo M2 receptor activation induces desensitization to mechanical and heat stimuli by a down-regulation of VR1 expression and by the inhibition of PKCϵ activity hindering its translocation to the plasma membrane, as suggested by in vitro experiments.

Formulation optimization of arecoline patches.

The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline.

The expression of O(6) -methylguanine-DNA methyltransferase in human oral keratinocytes stimulated with arecoline.

BACKGROUND: O(6) -methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that can protect cells from carcinogenic effects of alkylating agents by removing adducts from the O(6) position of guanine. Evidences indicated that areca quid chewing may increase the risk of oral squamous cell carcinoma (OSCC). This study was to investigate the role of MGMT expression in OSCCs and the normal oral tissues. METHODS: Thirty-two OSCCs from areca quid chewers and ten normal oral tissue biopsy samples without areca quid chewing were analyzed by the immunohistochemistry for MGMT. Primary human oral keratinocytes (HOKs) were challenged with arecoline, the major alkaloid of areca nut, by Western blot. Nicotine, an important component of cigarette smoke, was added to find the possible regulatory mechanisms. RESULTS: Significant association was observed between low MGMT expression and advanced clinical stage of OSCCs and lymph node metastasis (P = 0.03). MGMT expression was significantly higher in patients only chewing areca quid than patients both chewing areca quid and smoking (P = 0.028). Arecoline was found to elevate MGMT expression in a dose- and time-dependent manner. The addition of nicotine was found to enhance arecoline-induced MGMT expression. CONCLUSION: Our results indicate that MGMT could be used clinically as a predictive marker for tumor processing, the potential for lymph node metastasis as well as advanced clinical stage. MGMT expression was significantly upregulated by arecoline in HOKs. Nicotine has a synergistic effect of arecoline-induced MGMT expression. The cigarette smoking may act synergistically in the pathogenesis of OSCC in areca quid chewers via the upregulation of MGMT.

Arecoline decreases interleukin-6 production and induces apoptosis and cell cycle arrest in human basal cell carcinoma cells.

Arecoline, the most abundant areca alkaloid, has been reported to decrease interleukin-6 (IL-6) levels in epithelial cancer cells. Since IL-6 overexpression contributes to the tumorigenic potency of basal cell carcinoma (BCC), this study was designed to investigate whether arecoline altered IL-6 expression and its downstream regulation of apoptosis and the cell cycle in cultured BCC-1/KMC cells. BCC-1/KMC cells and a human keratinocyte cell line, HaCaT, were treated with arecoline at concentrations ranging from 10 to 100µg/ml, then IL-6 production and expression of apoptosis- and cell cycle progress-related factors were examined. After 24h exposure, arecoline inhibited BCC-1/KMC cell growth and decreased IL-6 production in terms of mRNA expression and protein secretion, but had no effect on HaCaT cells. Analysis of DNA fragmentation and chromatin condensation showed that arecoline induced apoptosis of BCC-1/KMC cells in a dose-dependent manner, activated caspase-3, and decreased expression of the anti-apoptotic protein Bcl-2. In addition, arecoline induced progressive and sustained accumulation of BCC-1/KMC cells in G2/M phase as a result of reducing checkpoint Cdc2 activity by decreasing Cdc25C phosphatase levels and increasing p53 levels. Furthermore, subcutaneous injection of arecoline led to decreased BCC-1/KMC tumor growth in BALB/c mice by inducing apoptosis. This study demonstrates that arecoline has potential for preventing BCC tumorigenesis by reducing levels of the tumor cell survival factor IL-6, increasing levels of the tumor suppressor factor p53, and eliciting cell cycle arrest, followed by apoptosis.

Effect of magnesium chloride on psychomotor activity, emotional status, and acute behavioural responses to clonidine, d-amphetamine, arecoline, nicotine, apomorphine, and L-5-hydroxytryptophan.

BACKGROUND: The beneficial effects of magnesium (Mg) salts on central manifestations of Mg deficiency are well known. Mg replacement therapy can be effective to prevent some of the serious depression-like and anxiety-related behaviour sequelae of Mg deficiency. However, few experimental studies have been undertaken on Mg-deficiency-induced behavioural changes. Even fewer studies have been carried out on acute behavioural responses to clonidine, D-amphetamine, arecoline, nicotine, apomorphine, and L-5-hydroxytryptophan (HTP), which might characterize possible neuromediator changes in Mg deficiency. The effects of correcting Mg deficiency by magnesium chloride (MgCl2 · 6H2O) and the combination of this salt with vitamin B6, on the behavioural manifestations of Mg deficiency have never been described as well. OBJECTIVE: The aims of this study were: to estimate effect of MgCl2 · 6H2O alone and in combination with vitamin B6 on acute behavioural responses to agonists or blockers of the main neurotransmitter systems in CNS, psychomotor activity and emotional status of rats fed with Mg-deficient diet for 49 days. In our study open field test has shown that in Mg-deficient rats locomotor activity and vertical activity, number of visiting and residence time in central squares were decreased significantly. In the elevated plus maze test, the number of visiting open arms and residence time of rats were significantly less as compared with the control group. In the forced swimming test, time immobile was significantly increased by 44.29% and time of swimming was decreased by 52.79% compared to control. RESULTS: In our study Mg-deficient rats were more sensitive to d-amphetamine-induced motor stereotypes. Mg deficiency antagonized 5-hydroxytryptophan-induced head-twitch response and arecoline-induced tremor. Supplement of MgCl2 · 6H2O with vitamin B6 administered to a Mg-deficient rat increased the Mg level in plasma and erythrocytes. Furthermore, this increase was in relation to vitamin B6 given to the animal. Mg supplementation alone and in combination with pyridoxine normalized acute behavioural responses to d-amphetamine, 5-hydroxytryptophan, and arecoline in Mg deficient rats with a return to pre-deficient levels observed in the Mg sufficient group. DISCUSSION: Combination of Mg salts and pyridoxine hydrochloride can be effective at treating some behavior form of primary Mg deficiency.

Imaging decreased brain docosahexaenoic acid metabolism and signaling in iPLA(2)ß (VIA)-deficient mice.

Ca(2+)-independent phospholipase A(2)ß (iPLA(2)ß) selectively hydrolyzes docosahexaenoic acid (DHA, 22:6n-3) in vitro from phospholipid. Mutations in the PLA2G6 gene encoding this enzyme occur in patients with idiopathic neurodegeneration plus brain iron accumulation and dystonia-parkinsonism without iron accumulation, whereas mice lacking PLA2G6 show neurological dysfunction and neuropathology after 13 months. We hypothesized that brain DHA metabolism and signaling would be reduced in 4-month-old iPLA(2)ß-deficient mice without overt neuropathology. Saline or the cholinergic muscarinic M(1,3,5) receptor agonist arecoline (30 mg/kg) was administered to unanesthetized iPLA(2)ß(-/-), iPLA(2)ß(+/-), and iPLA(2)ß(+/+) mice, and [1-(14)C]DHA was infused intravenously. DHA incorporation coefficients k* and rates J(in), representing DHA metabolism, were determined using quantitative autoradiography in 81 brain regions. iPLA(2)ß(-/-) or iPLA(2)ß(+/-) compared with iPLA(2)ß(+/+) mice showed widespread and significant baseline reductions in k* and J(in) for DHA. Arecoline increased both parameters in brain regions of iPLA(2)ß(+/+) mice but quantitatively less so in iPLA(2)ß(-/-) and iPLA(2)ß(+/-) mice. Consistent with iPLA(2)ß's reported ability to selectively hydrolyze DHA from phospholipid in vitro, iPLA(2)ß deficiency reduces brain DHA metabolism and signaling in vivo at baseline and following M(1,3,5) receptor activation. Positron emission tomography might be used to image disturbed brain DHA metabolism in patients with PLA2G6 mutations.

Systemic administration of arecoline reduces ethanol-induced sleeping through activation of central muscarinic receptor in mice.

BACKGROUND: Epidemiological evidence of co-use of alcohol and areca nuts suggests a potential central interaction between arecoline, a major alkaloid of areca and a muscarinic receptor agonist, and ethanol. Moreover, the central cholinergic system plays an important role in the depressant action of ethanol and barbiturates. The purpose of this study was to investigate the effects of arecoline on pentobarbital- and ethanol-induced hypnosis in mice. METHODS: Male ICR mice were tested for locomotor activity following acute systemic administration of ethanol alone, arecoline alone, or ethanol plus arecoline. For the loss of the righting reflex (LORR) induced by pentobarbital and ethanol, sleep latency and sleeping duration were evaluated in mice treated with arecoline alone or the combination of arecoline and scopolamine or methscopolamine. RESULTS: Ethanol (1.0 to 3.0 g/kg, i.p.) reduced locomotor activity significantly and a declining trend was observed after treatment with arecoline (0.25 to 1.0 mg/kg, i.p.), but there were no synergistic effects of ethanol and arecoline on locomotor activity. The experiments on LORR demonstrated that arecoline (0.125 to 1.0 mg/kg, s.c.) shortened the duration of sleeping induced by ethanol (4.0 g/kg, i.p.), but not pentobarbital (45 mg/kg, i.p.). In addition, alterations of sleep latency were not obvious in both pentobarbital- and ethanol-induced LORR. Statistical analyses revealed that scopolamine (centrally acting), but not methscopolamine (peripherally acting), could antagonize the effect of arecoline on the duration of ethanol-induced LORR in mice. CONCLUSIONS: These results suggest that central muscarinic receptor is a pharmacological target for the action of arecoline to modulate ethanol-induced hypnosis.

The metronomic combination of paclitaxel with cholinergic agonists inhibits triple negative breast tumor progression. Participation of M2 receptor subtype.

Triple negative tumors are more aggressive than other breast cancer subtypes and there is a lack of specific therapeutic targets on them. Since muscarinic receptors have been linked to tumor progression, we investigated the effect of metronomic therapy employing a traditional anti-cancer drug, paclitaxel plus muscarinic agonists at low doses on this type of tumor. We observed that MDA-MB231 tumor cells express muscarinic receptors, while they are absent in the non-tumorigenic MCF-10A cell line, which was used as control. The addition of carbachol or arecaidine propargyl ester, a non-selective or a selective subtype 2 muscarinic receptor agonist respectively, plus paclitaxel reduces cell viability involving a down-regulation in the expression of ATP "binding cassette" G2 drug transporter and epidermal growth factor receptor. We also detected an inhibition of tumor cell migration and anti-angiogenic effects produced by those drug combinations in vitro and in vivo (in NUDE mice) respectively. Our findings provide substantial evidence about subtype 2 muscarinic receptors as therapeutic targets for the treatment of triple negative tumors.

Arecoline-regulated ataxia telangiectasia mutated expression level in oral cancer progression.

BACKGROUND: Ataxia telangiectasia mutated (ATM) regulates DNA repair and cell cycle. The present study analyzed arecoline-induced ATM expression during oral cancer progression. METHODS: In vitro studies were performed using oral squamous cell carcinoma (OSCC) cell lines treated with arecoline to analyze cell response and ATM regulation. in vivo studies were performed using immunohistochemistry to detect ATM expression in normal, oral potentially malignant disorder (OPMD), and OSCC tissues. RESULTS: Low-dose arecoline induced cell proliferation, ATM promoter activity, and DNA repair. High-dose arecoline induced cell cycle arrest, apoptosis, and DNA damage. ATM was overexpressed in OPMD tissues but was downregulated in OSCC tissues. ATM expression level was associated with the risk of developing dysplasia, buccal-OSCC, and with OSCC survival rate. CONCLUSION: High ATM expression helps DNA repair mechanisms to maintain the cells in the OPMD stage, but low ATM expression causes DNA damage accumulation to increase cell malignancy.

Periodontal health status in pan chewers with or without the use of tobacco.

BACKGROUND: Betel nut and tobacco chewing is a common practice in south-east Asia. In India, betel nut is commonly chewed in the form of pan, with or without tobacco. Numerous studies have shown the carcinogenic potential of betel nut and tobacco. Betel nut and tobacco are also known to have deleterious effects on the oral tissues. PURPOSE: The aim of our study was to evaluate and compare the periodontal effects of pan chewing with or without the use of tobacco as an ingredient. MATERIALS AND METHODS: The periodontal status of 300 subjects (150 subjects were pan chewers with tobacco and 150 subjects were pan chewers without tobacco) was evaluated using the community periodontal index (CPI). The subjects were selected by the stratified random sampling method. The oral hygiene status of the subjects was evaluated using the simplified oral hygiene index. RESULTS: CPI code-4, with a probing depth of 6 mm or more, was seen in 30% of pan chewers with tobacco compared with 7.3% of pan chewers without tobacco. It was found that pan chewers with tobacco had 4.7 times more risk of having pockets than pan chewers without tobacco. The higher codes of loss of attachment were seen in pan chewers with tobacco compared with pan chewers without tobacco. It was found that pan chewers with tobacco had 7 times more risk of having loss of attachment when compared with the pan chewers without tobacco. CONCLUSIONS: The results show higher incidence of periodontal diseases in pan chewers who use tobacco compared with pan chewers who do not use tobacco. Based on the results, it was concluded that, although betel nut has deleterious effects on the periodontium, the addition of tobacco leads to a synergistic effect between betel nut and tobacco on the periodontal tissues.

Arecoline cannot alter testicular dysfunction and pineal activation caused by noise in wistar rat.

Millions of people consume betel nut for increased capacity to work and for stress reduction. The nut contains arecoline, which has multiple side effects on endocrine functions. Objective of the work is to investigate pineal-testicular responses to noise and after arecoline treatment in noise in rats. Noise exposure (100 dB, 6 h daily, 10 days) caused pineal stimulation ultrastructurally and at indoleamines level. Leydig cell dysfunction with fall of testosterone level and suppression of sex accessories were noticed. In contrast, pineal activity was inhibited and reproductive functions were stimulated after arecoline administration, confirmed from reversed changes to those of noise. Arecoline treatment in noise exposure showed same results as in noise both in pineal and in reproductive functions. It is concluded that noise causes testicular dysfunction probably by gonadotropin suppression induced by pineal melatonin in noise. Furthermore, arecoline cannot prevent it in noise in rats.

The metabolomics of (+/-)-arecoline 1-oxide in the mouse and its formation by human flavin-containing monooxygenases.

The alkaloid arecoline is a main constituent of areca nuts that are chewed by approximately 600 million persons worldwide. A principal metabolite of arecoline is arecoline 1-oxide whose metabolism has been poorly studied. To redress this, synthetic (+/-)-arecoline 1-oxide was administered to mice (20mg/kg p.o.) and a metabolomic study performed on 0-12h urine using ultra-performance liquid chromatography-coupled time-of-flight mass spectrometry (UPLC-TOFMS) with multivariate data analysis. A total of 16 mass/retention time pairs yielded 13 metabolites of (+/-)-arecoline 1-oxide, most of them novel. Identity of metabolites was confirmed by tandem mass spectrometry. The principal pathways of metabolism of (+/-)-arecoline 1-oxide were mercapturic acid formation, with catabolism to mercaptan and methylmercaptan metabolites, apparent CC double-bond reduction, carboxylic acid reduction to the aldehyde (a novel pathway in mammals), N-oxide reduction, and de-esterification. Relative percentages of metabolites were determined directly from the metabolomic data. Approximately, 50% of the urinary metabolites corresponded to unchanged (+/-)-arecoline 1-oxide, 25% to other N-oxide metabolites, while approximately, 30% corresponded to mercapturic acids or their metabolites. Many metabolites, principally mercapturic acids and their derivatives, were excreted as diastereomers that could be resolved by UPLC-TOFMS. Arecoline was converted to arecoline 1-oxide in vitro by human flavin-containing monooxygenases FMO1 (K(M): 13.6+/-4.9muM; V(MAX): 0.114+/-0.01nmolmin(-1)microg(-1) protein) and FMO3 (K(M): 44.5+/-8.0microM; V(MAX): 0.014+/-0.001nmolmin(-1)microg(-1) protein), but not by FMO5 or any of 11 human cytochromes P450. This report underscores the power of metabolomics in drug metabolite mining.

Multiple-dose arecoline infusions in Alzheimer's disease.

Twelve patients with dementia of the Alzheimer type received two-hour infusions of placebo and the muscarinic cholinergic agonist arecoline hydrobromide at rates of 1, 2, and 4 mg/h in a double-blind, randomized fashion. These infusions resulted in dose-dependent physiologic and neuroendocrine effects consistent with central cholinergic stimulation. Infusions were generally well tolerated. No statistically significant improvement in performance on most cognitive tasks assessing knowledge memory and episodic learning and memory was observed at any dose, although marginal improvement in picture recognition ability and in ratings of word-finding were observed at the lower doses. Psychomotor activation and slightly improved affect were reliably observed at the lower doses, whereas increasing psychomotor retardation was observed at the highest dose. The data support a role for central cholinergic modulation of some aspects of cognition, behavior, and affect in this population. The apparent greater behavioral sensitivity of patients with Alzheimer's disease in comparison with subject populations previously studied, as well as the altered dose responsiveness, merit further study in relationship to normal aging.

The cholinergic rapid eye movement induction test with arecoline in depression.

The cholinergic rapid eye movement (REM) induction test using arecoline hydrobromide, a cholinergic muscarinic receptor agonist, was studied in patients with affective disorder and in normal controls to determine whether or not depression is associated with enhanced induction of REM sleep by muscarinic agonists. Arecoline induced REM sleep in a dose-dependent fashion in both patients and controls compared with placebo infusions. Compared with normal controls, patients entered REM sleep significantly more rapidly following intravenous administration of 1.0 mg of arecoline hydrobromide than they did following administration of 0.5 mg of arecoline hydrobromide or placebo. These results, as well as those of previous studies, support the hypothesis that patients with affective disorder show a functional supersensitive induction of REM sleep in response to muscarinic receptor agonists and may be consistent with the hypothesis that functional muscarinic receptor "up regulation" is associated with depression.