Search results for "Transmitter"
showing 10 items of 348 documents
Chapter 9 Nicotinic acetylcholine receptors on hippocampal neurons: cell compartment-specific expression and modulatory control of channel activity
1996
Publisher Summary The neuronal nicotinic acetylcholine receptors (nAChRs) are differentially expressed on the somato-dendritic surface of hippocampal neurons. This chapter demonstrates that various ions and drugs play a crucial role in modulating the activity of neuronal nAChRs. Considering the diversity of the neurotransmitter receptors and their binding sites and the diversity of substances, which can act simultaneously as a primary agonist of one receptor and an allosteric modulator of a different receptor, an enormous variety of combinatorial possibilities can be achieved in the brain giving rise to very complex neuronal networks. The characterization of the diversity of many receptors …
Histaprodifens: synthesis, pharmacological in vitro evaluation, and molecular modeling of a new class of highly active and selective histamine H(1)-r…
2000
A new class of histamine analogues characterized by a 3, 3-diphenylpropyl substituent at the 2-position of the imidazole nucleus has been prepared outgoing from 4,4-diphenylbutyronitrile (4b) via cyclization of the corresponding methyl imidate 5b with 2-oxo-4-phthalimido-1-butyl acetate or 2-oxo-1,4-butandiol in liquid ammonia, followed by standard reactions. The title compounds displayed partial agonism on contractile H(1) receptors of the guinea-pig ileum and endothelium-denuded aorta, respectively, except 10 (histaprodifen; 2-[2-(3, 3-diphenylpropyl)-1H-imidazol-4-yl]ethanamine) which was a full agonist in the ileum assay. While 10 was equipotent with histamine (1), methylhistaprodifen (…
Anxiolytic-like effects of acute and chronic GABA transporter inhibition in rats.
2002
Acute GABA transporter inhibition can induce anxiolytic-like behaviors. The present analysis addressed whether chronic treatment (23 days via drinking water) with a GABA transporter inhibitor affects rat behavior similar to acute treatment and interferes with additional benzodiazepine-receptor agonistic treatment. Seventy-one rats divided into seven groups were acutely treated with either vehicle, diazepam (2 mg/kg), zolpidem (0.05 mg/kg), tiagabine (19 mg/kg) or chronically with tiagabine with or without acute diazepam or zolpidem. Animals were behaviorally characterized in an elevated plus-maze. None of the treatments induced changes in the activity of the animals. Acute and chronic treat…
Intra-Nasally Administered Oligopeptide Lunasin Acts as a Possible Anti-Psychotic Agent in Mice Models
2019
Background and Objectives: Previously we have shown that synthetic lunasin, a 43 amino acid residue-containing peptide, after its central (intracisternal) administration in mice demonstrated antagonism against dopaminergic drug behavioural effects, indicating a putative antipsychotic/anti-schizophrenic profile of lunasin. The aims of the present studies were: to test whether lunasin would show an influence on the dopaminergic system after intranasal administration, and to examine the effect(s) of lunasin on serotonin and glutamatergic systems, which could play an essential role in antipsychotic action. Materials and Methods: Lunasin was administered intra-nasally at doses 0.1 and 1 nmol/mou…
Structural Mechanism of N-Methyl-D-Aspartate Receptor Type 1 Partial Agonism
2012
N-methyl-D-aspartate (NMDA) receptors belong to a family of ionotropic glutamate receptors that contribute to the signal transmission in the central nervous system. NMDA receptors are heterotetramers that usually consist of two GluN1 and GluN2 monomers. The extracellular ligand-binding domain (LBD) of a monomer is comprised of discontinuous segments that form the functional domains D1 and D2. While the binding of a full agonist glycine to LBD of GluN1 is linked to cleft closure and subsequent ion-channel opening, partial agonists are known to activate the receptor only sub-maximally. Although the crystal structures of the LBD of related GluA2 receptor explain the mechanism for the partial a…
Agonist potency differentiates G protein activation and Ca2+ signalling by the orexin receptor type 1.
2005
The G protein coupling characteristics of a flag epitope-tagged orexin receptor type 1 (OX1R) was investigated in HEK293 cells. Immunoprecipitation of the OX1R and immunoblotting revealed interactions with Gq/G11 proteins as well as with Gs and Gi proteins. Stimulation with orexin-A did not affect the ability of the OX1R to coprecipitate Gq/G11 proteins, but it robustly elevated the intracellular concentration of Ca2+, [Ca2+]i. No changes in cAMP levels could be detected upon receptor stimulation. To get further insight into the functional correlation of G protein activation and Ca2+ signalling, we used baculovirus transduction to express chimeric G proteins, containing the Galphas protein …
Biogenic Amines Modulate Olfactory Receptor Neurons Firing Activity in Mamestra brassicae
2001
The modulatory effects of the biogenic amines octopamine and serotonin on pheromonal receptor neurons of Mamestra brassicae were investigated. The responses to sex pheromone components of two cells types (A and B) in single male long sensilla trichodea were monitored. Cell types A and B do not respond to the same compound. The response of type A to a pulse of the major sex pheromone component increased 5 min after octopamine injection. Responses of type B to other odorants increased after 30 min. In the absence of any pheromone stimulation the background firing activity of type A increased following octopamine injection. This background activity was used to evaluate the kinetics of octopami…
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…
Characterization of sensory neurotransmission and its inhibition via alpha 2B-adrenoceptors and via non-alpha 2-receptors in rabbit iris.
1993
To find out whether, and which type of, adrenoceptors mediate prejunctional inhibition of sensory neurotransmitter release from trigeminal fibres, the modulation of twitch response to electrical field stimulation on rabbit isolated iris was investigated. Evoked iris sphincter contractions consisted of a minor fast cholinergic and a large slow component. The latter was unaffected by atropine and guanethidine, hence nonadrenergic noncholinergic in nature (NANC), but nearly completely abolished by capsaicin pretreatment and by the neurokinin receptor antagonist spantide. The response was probably not mediated by NK2 receptors as SR 48,968, an NK2 selective nonpeptide antagonist, failed to redu…