Alpha4beta2

The up-regulation of α4β2* nicotinic acetylcholine receptors (nAChRs) by chronic nicotine is a cell-delimited process and may be necessary and sufficient for the initial events of nicotine dependence. Clinical literature documents an inverse relationship between a person's history of tobacco use and his or her susceptibility to Parkinson's disease; this may also result from up-regulation. This study visualizes and quantifies the subcellular mechanisms involved in nicotine-induced nAChR up-regulation by using transfected fluorescent protein (FP)-tagged α4 nAChR subunits and an FP-tagged Sec24D endoplasmic reticulum (ER) exit site marker...

AIM: To establish the whole-cell recording techniques of the neuronal alpha4beta2, alpha4beta4, and alpha7-nicotinic acetylcholine receptors heterologously expressed in SH-EP1 cell line and discuss the electrophysiological characteristics of their open states. METHODS: The cells were cultured with DEME medium(high glucose) and suitable for electrophysiological experiments three days after passage. The receptors were induced from resting states into open states by rapid application of nicotine (alpha4beta2, alpha4beta4) or choline (alpha7)...

Varenicline (Champix) is an alpha4beta2 nicotinic receptor antagonist that is used orally for treatment of nicotine dependence. We conducted a study to examine the sustainable efficacy of varenicline in smoking cessation. The subjects were 148 outpatients (113 men, 35 women; average age; 54.4 +/- 14.0 years) at 6 different hospitals, and their adverse events were monitored in each hospital. The 4-week continuous abstinence rates of smoking cessation were 17.6%, 75.0%, and 84.6% in groups treated for 4 or fewer weeks, 5 to 8 weeks, and 9 to 12 weeks, respectively, with the rate showing a significant increase according to treatment period...

Cognitive disorders in the course of mental illnesses are one of the most important and most difficult therapeutic problems related to those illnesses and they regard attention, memory, learning and sensory modulation. The limited number of nicotinic receptors (subtypes alpha7 and alpha4beta2) seems to cause the incidence and exacerbation of cognitive deficits in such patients. In patients with schizophrenia, the impairment of cognitive processes is also a side-effect of neuroleptics. The characteristics and intensity of the negative effect of antipsychotics on cognitive functions depends on the pharmacological action of those drugs and on the effect on dopamine and serotoninergic receptors in particular...

INTRODUCTION:   Varenicline, a partial agonist/antagonist of the alpha4beta2 nicotinic acetylcholine receptors, is effective in smoking cessation, which was demonstrated by several randomized, controlled clinical trials. OBJECTIVES:   In the present study, we evaluated the practical efficacy of varenicline for smoking cessation in patients who visited a pulmonary clinic at a university-affiliated hospital in South Korea. MATERIALS AND METHODS:   Varenicline was prescribed to smokers after brief, standardized, individual counseling from June 2007 to January 2009...

Polychlorinated biphenyls (PCBs) and the structurally related polybrominated diphenyl ethers (PBDEs) are abundant persistent organic pollutants that exert several comparable neurotoxic effects. Importantly, hydroxylated metabolites of PCBs and PBDEs have an increased neurotoxic potency. Recently, we demonstrated that PCBs can act as (partial) agonist on GABA(A) neurotransmitter receptors, with PCB-47 being the most potent congener. It is, however, unknown whether PBDE-47 and its metabolite 6-OH-PBDE-47 exert similar effects and if these effects are limited to GABA(A) receptors only...

Varenicline (Chantix, Champix) is an orally administered alpha4beta2 nicotinic acetylcholine receptor partial agonist that is indicated as an aid to smoking cessation. Varenicline was an effective aid to smoking cessation and was generally well tolerated in clinical trials, although more data are needed regarding the potential for neuropsychiatric events. The costs associated with varenicline are offset by direct savings associated with the reduction in smoking-related diseases. Indeed, despite their limitations, available pharmacoeconomic analyses from numerous countries support the use of varenicline for 12 or 24 weeks as a cost-effective treatment relative to other smoking cessation therapies in smokers who wish to quit smoking...

Water is an essential component for many biological processes. Pauling proposed that water might play a critical role in general anesthesia by forming water clathrates around anesthetic molecules. To examine potential involvement of water in general anesthesia, we analyzed water within alpha4beta2 nAChR, a putative protein target hypersensitive to volatile anesthetics. Experimental structure-derived closed- and open-channel nAChR systems in a fully hydrated lipid bilayer were examined using all-atom molecular dynamics simulations...

Effects of selective and non-selective neurotoxic compounds on membrane currents mediated by nicotinic acetylcholine receptors (nAChR), natively expressed in cultured cells and artificially expressed in Xenopus oocytes, have been investigated in vitro using voltage clamp techniques. Mammalian neuronal nAChR in cultured mouse N1E-115 cells, muscle type nAChR in cultured mouse BC3H1 cells and insect neuronal nAChR in dissociated locust thoracic ganglion neurons show interspecies differences in sensitivity to neurotoxic compounds...

BACKGROUND AND PURPOSE: A fundamental property of transmitter-gated ion channels is the probability a channel will be open (P(open)) when stimulated by a concentration of agonist that elicits a maximal response. This value is critical for interpreting steady-state concentration-response relationships in terms of channel activation, and for understanding the actions of drugs that potentiate responses. We used analysis of non-stationary noise to estimate the maximal probability the nicotinic alpha4beta2 receptor is open...

Li and Steinbach apply nonstationary noise analysis to the whole-cell current responses of low sensitivity alpha4beta2 nAChR stably-expressed in HEK cells. These receptors represent one of the most important nAChR subtypes in brain, and also one of the most difficult to study in native tissues. They found the activating properties of the full agonists ACh and nicotine to be similar with regard to P(open) and single channel conductance, whereas the weak alpha4beta2 partial agonist cytisine caused channels to open with low probability but increased single channel conductance...

Alcohol abuse and alcoholism are serious and costly problem in USA. Thus, the development of anti-alcoholism agents could be very significant. The understanding of the neurochemical basis underlying the addictive properties of drugs of abuse is imperative for the development of new pharmacological means to reverse the addictive state, prevent relapse or to reduce the intake of addictive compounds. The nicotinic acetylcholine receptors (nAChRs) are important therapeutic targets for various diseases. Recent studies have revealed that the alpha3beta2, alpha3beta3, and alpha6 subunits of nAChR protein family might be pharmacological targets for developing new drugs in the treatment of alcoholism...

Nicotine has been well established as an impulsive action-inducing agent, but it remains unknown whether endogenous acetylcholine affects impulsive action via nicotinic acetylcholine receptors. In the present study, the 3-choice serial reaction time task (3-CSRTT), a simple and valid assessment of impulsive action, was employed. Male Wistar/ST rats were trained to detect and respond to 1-s flashes of light presented in one of three holes until stable performance was achieved. Following training on the 3-CSRTT, rats received intracerebroventricular injections of the preferential alpha4beta2 nicotinic acetylcholine receptor antagonist dihydro-beta-erythroidine (DHbetaE; 0, 3, 10, and 30 microg) or the selective alpha7 nicotinic acetylcholine receptor antagonist methyllycaconitine (MLA; 0, 3, 10, and 30 microg) 5 min before test sessions...

Positive allosteric modulators of centrally expressed nicotinic acetylcholine receptors have therapeutic potentials in areas of cognition, motor function and reward. Several chemical classes of allosteric modulators that are selective for alpha7 nicotinic receptors have been characterised, but potentiators for the most widely expressed alpha4beta2 nicotinic receptor subtype are few and less defined, owing probably to the difficulty to achieve selectivity over other heteromeric receptor subtypes. 2087101 (2-amino-5-keto)thiazole) is a potent potentiator of both alpha7 and alpha4beta2 receptors and it has selectivity against the alpha3beta4 subtype, which may be responsible for the undesirable peripheral side effects...

Pharmacophore models for nicotinic agonists have been proposed for four decades. Central to these models is the presence of a cationic nitrogen and a hydrogen bond acceptor. It is now well-established that the cationic center makes an important cation-pi interaction to a conserved tryptophan, but the donor to the proposed hydrogen bond acceptor has been more challenging to identify. A structure of nicotine bound to the acetylcholine binding protein predicted that the binding partner of the pharmacophore's second component was a water molecule, which also hydrogen bonds to the backbone of the complementary subunit of the receptors...

Many patients with depression fail to derive sufficient benefit from available treatment options, with up to a third never reaching remission despite multiple trials of appropriate treatment. Novel antidepressant agents are needed, and drugs targeting nicotinic acetylcholine receptors (nAChRs) appear to hold promise in this regard. nAChRs are involved in a variety of neurobiological systems implicated in the pathophysiology of depression. In addition to their role in cholinergic neurotransmission, they modulate dopamine function and influence inflammation and hypothalamic-pituitary-adrenal axis activity...

The nicotinic acetylcholine receptors (nAChR) assembled from alpha4 and beta2 subunits are the most densely expressed subtype in the brain. Concentration-effect curves for agonist activation of alpha4beta2*-nAChR are biphasic. This biphasic agonist sensitivity is ascribed to differences in subunit stoichiometry. The studies described here evaluated desensitization elicited by low concentrations of epibatidine, nicotine, cytisine or methylcarbachol of brain alpha4beta2-nAChR function measured with acetylcholine-stimulated (86)Rb(+) efflux from mouse thalamic synaptosomes...

Carbamazepine (5H-dibenz[b,f]azepine-5-carboxamide) and oxcarbazepine (10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide) are widely used for the treatment of partial epilepsy. Recent work indicates that these drugs, in addition to targeting voltage-gated Na(+) channels, can modulate ligand-gated channels. These compounds appear to be particularly effective for treatment of nocturnal frontal lobe epilepsy, which can be caused by mutant neuronal nicotinic receptors. We compared the effects of carbamazepine and oxcarbazepine on heteromeric nicotinic receptors to better understand the underlying mechanism of the effect of these drugs in epileptic patients...

Allosteric modulation of neuronal nicotinic acetylcholine receptors (nAChRs) is considered to be one of the most promising approaches for therapeutics. We have previously reported on the pharmacological activity of several compounds that act as negative allosteric modulators (NAMs) of nAChRs. In the following studies, the effects of 30 NAMs from our small chemical library on both human alpha4beta2 (Halpha4beta2) and human alpha3beta4 (Halpha3beta4) nAChRs expressed in human embryonic kidney ts201 cells were investigated...

The Erythrina alkaloids erysodine and dihydro-beta-erythroidine (DHbetaE) are potent and selective competitive inhibitors of alpha4beta2 nicotinic acetylcholine receptors (nAChRs), but little is known about the molecular determinants of the sensitivity of this receptor subtype to inhibition by this class of antagonists. We addressed this issue by examining the effects of DHbetaE and a range of aromatic Erythrina alkaloids on [(3)H]cytisine binding and receptor function in conjunction with homology models of the alpha4beta2 nAChR, mutagenesis, and functional assays...