Search results for "Nicotinic Receptor"

Na+ ions binding to the bradykinin B2 receptor suppress agonist-independent receptor activation.

1996

Control of the balance between receptor activation and inactivation is a prerequisite for seven transmembrane domain (7TM) receptor function. We asked for a mechanism to stabilize the inactive receptor conformation which prevents agonist-independent receptor activation. Na+ ions have reciprocal effects on agonist versus antagonist interaction with various 7TM receptors. To investigate the Na+ dependence of receptor activation we chose the bradykinin B2 receptor as a prototypic 7TM receptor. Decrease of the intracellular Na+ content from 40 mM to 10 mM of COS-1 cells transiently expressing rat B2 receptors activated the B2 receptor in the absence of agonist as shown by a 3-fold increase in t…

Minireview: Nicotinic Acetylcholine Receptors on Hippocampal Neurons: Distribution on the Neuronal Surface and Modulation of Receptor Activity

1997

The recent development of a technique that uses infrared microscopy for the visualization of well-defined areas on the surface of neurons, and a computerized system of micromanipulators led to the discovery that functional nicotinic acetylcholine receptors (nAChRs) are expressed at higher density on the dendrites than on the soma of rat hippocampal neurons. The finding that the expression of alpha-bungarotoxin-sensitive, alpha 7-bearing, nAChRs and dihydro-beta-erythroidine-sensitive, alpha 4 beta 2 nAChRs tends to increase along the dendritic length suggests that these receptors may be highly involved in the integration of synaptic functions in hippocampal neurons. The present report also …

Modulatory control by non-competitive agonists of nicotinic cholinergic neurotransmission in the central nervous system

1995

Abstract Several exogenous and endogenous compounds have been discovered that act on nicotinic acetylcholine receptors as non-competitive agonists (NCA) of low efficacy, and probably also as allosteric regulators of the receptor's sensitivity to acetylcholine. Nicotinic NCAs may be viewed as another facet in the increasingly complex picture of vertebrate brain organization, i.e. they may be part of a higher level ‘chemical’ network that overlays the neuronal network of the CNS. Furthermore, exogenous NCAs may provide a new therapeutic approach to Alzheimer's dementia.

Expression of the α4 isoform of the nicotinic acetylcholine receptor in the fetal human cerebral cortex

2001

Nicotinic acetylcholine receptors are likely to play an important role in neuronal migration during development. Furthermore, the alpha4 receptor subunit gene is related to a hereditary juvenile form of epilepsy. Only little information is available, however, on the expression of cerebrocortical nicotinic acetylcholine receptors during human fetal development. Using non-isotopic in situ hybridization and immunohistochemistry, we have studied the distribution of the alpha4 subunit of the nicotinic acetylcholine receptor mRNA and protein in the human frontal cortex at middle (17-24 weeks of gestation) and late (34-42 weeks of gestation) fetal stages. Both, alpha4 receptor mRNA and alpha4 rece…

The nicotinic acetylcholine receptor agonist (±)-epibatidine increases FGF-2 mRNA and protein levels in the rat brain

2000

Abstract In a previous work, we showed that acute intermittent nicotine treatment up-regulates the level of fibroblast growth factor-2 (FGF-2) mRNA in brain regions of tel- and mesencephalon of rats suggesting that neuroprotective effect of (−)nicotine may, at least in part, involve an activation of the neuronal FGF-2 signalling. The present experiments were designed to extend the study on the nicotinic receptor mediated up-regulation of FGF-2 mRNA levels to the use of the potent nicotinic acetylcholine receptor (nAChR) agonist (±)-epibatidine. The (±)-epibatidine treatment led to a strong and long lasting up-regulation of FGF-2 mRNA expression in the cerebral cortex, in the hippocampal for…

Neurotrophic effects of central nicotinic receptor activation

2000

A growing number of data have shown that compounds interacting with neuronal nicotinic acetylcholine receptors (nAChRs) have, both in vivo and in vitro, the potential to be neuroprotective and that treatment with nAChR agonists elicit long-lasting improvement of cognitive performance in a variety of behavioural tests in rats, monkeys and humans. Epidemiological and clinical studies suggested also a potential neuroprotective/trophic role of (-)-nicotine in neurodegenerative disease, such as Alzheimer's disease and Parkinson's disease. This neuroprotective/trophic role of nAChR activation has been mainly mediated by alpha7 and alpha4beta2 nAChR subtypes, as evidenced using selective nAChR ant…

Increased sensitivity of the alpha-2 neuronal nicotinic receptor causes familial epilepsy with nocturnal wandering and ictal fear

2006

α7 Nicotinic acetylcholine receptors and modulation of gabaergic synaptic transmission in the hippocampus

2000

The present report provides new findings regarding modulation of gamma-aminobutyric acid (GABA) transmission by alpha7 nicotinic receptor activity in CA1 interneurons of rat hippocampal slices. Recordings were obtained from tight-seal cell-attached patches of the CA1 interneurons, and agonists were delivered to the neurons via a modified U-tube. Application for 6 s of the alpha7 nicotinic receptor-selective agonist choline (or =1 mM) to all CA1 interneurons tested triggered action potentials that were detected as fast current transients. The activity triggered by choline terminated well before the end of the agonist pulse, was blocked by the alpha7 nicotinic receptor antagonist methyllycaco…

Murine embryonic stem cell line CGR8 expresses all subtypes of muscarinic receptors and multiple nicotinic receptor subunits: Down-regulation of α4- …

2015

Non-neuronal acetylcholine mediates its cellular effects via stimulation of the G-protein-coupled muscarinic receptors and the ligand-gated ion channel nicotinic receptors. The murine embryonic stem cell line CGR8 synthesizes and releases non-neuronal acetylcholine. In the present study a systematic investigation of the expression of nicotinic receptor subunits and muscarinic receptors was performed, when the stem cells were grown in the presence or absence of LIF, as the latter condition induces early differentiation. CGR8 cells expressed multiple nicotinic receptor subtypes (α3, α4, α7, α9, α10, β1, β2, β3, β4, γ, δ, e) and muscarinic receptors (M1, M3, M4, M5); M2 was detected only in 2 …

Modulation of Hippocampal Circuits by Muscarinic and Nicotinic Receptors

2017

This article provides a review of the effects of activation of muscarinic and nicotinic receptors on the physiological properties of circuits in the hippocampal formation. Previous articles have described detailed computational hypotheses about the role of cholinergic neuromodulation in enhancing the dynamics for encoding in cortical structures and the role of reduced cholinergic modulation in allowing consolidation of previously encoded information. This article will focus on addressing the broad scope of different modulatory effects observed within hippocampal circuits, highlighting the heterogeneity of cholinergic modulation in terms of the physiological effects of activation of muscarin…