Thyroid hormones reduce nicotinic receptor mediated currents in SH-SY5Y neuroblastoma cells.

Background: Thyroid hormones (THs) are crucial for maturation and functioning of mammalian CNS. THs "classical" signaling involves nuclear receptors binding but also their non genomic actions, as rapid modulators of cell activity, are widely recognized. Since THs imbalance affects cognition and the cholinergic system is deeply involved in learning and memory processes we have studied THs effects at the level of the nicotinic acetylcholine receptors (nAchR).

Positive allosteric modulators of α7 nicotinic acetylcholine receptors affect neither the function of other ligand- and voltage-gated ion channels and acetylcholinesterase, nor β-amyloid content.

The activity of positive allosteric modulators (PAMs) of α7 nicotinic acetylcholine receptors (AChRs), including 3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2), 3-furan-2-yl-N-o-tolylacrylamide (PAM-3), and 3-furan-2-yl-N-phenylacrylamide (PAM-4), was tested on a variety of ligand- [i.e., human (h) α7, rat (r) α9α10, hα3-containing AChRs, mouse (m) 5-HT3AR, and several glutamate receptors (GluRs)] and voltage-gated (i.

Pro-cognitive activity in rats of 3-furan-2-yl-N-p-tolyl-acrylamide, a positive allosteric modulator of the α7 nicotinic acetylcholine receptor.

Background And Purpose: α7 nicotinic acetylcholine receptors (α7 nAChRs) may represent useful targets for cognitive improvement. The aim of this study is to compare the pro-cognitive activity of selective α7-nAChR ligands, including the partial agonists, DMXBA and A-582941, as well as the positive allosteric modulator, 3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2).

Experimental Approach: The attentional set-shifting task (ASST) and the novel object recognition task (NORT) in rats, were used to evaluate the pro-cognitive activity of each ligand [i.

PKCε and allopregnanolone: functional cross-talk at the GABAA receptor level.

Changes in GABAergic inhibition occur during physiological processes, during response to drugs and in various pathologies. These changes can be achieved through direct allosteric modifications at the γ-amino butyric acid (GABA) type A (GABAA) receptor protein level, or by altering the synthesis, trafficking and stability of the receptor. Neurosteroids (NSs) and protein kinase C (PKC) are potent modulators of GABAA receptors and their effects are presumably intermingled, even though evidence for this hypothesis is only partially explored.

Effects of neurosteroids on a model membrane including cholesterol: A micropipette aspiration study.

Amphiphilic molecules supposed to affect membrane protein activity could strongly interact also with the lipid component of the membrane itself. Neurosteroids are amphiphilic molecules that bind to plasma membrane receptors of cells in the central nervous system but their effect on membrane is still under debate. For this reason it is interesting to investigate their effects on pure lipid bilayers as model systems.

Effect of neurosteroids on a model lipid bilayer including cholesterol: An Atomic Force Microscopy study.

Amphiphilic molecules which have a biological effect on specific membrane proteins, could also affect lipid bilayer properties possibly resulting in a modulation of the overall membrane behavior. In light of this consideration, it is important to study the possible effects of amphiphilic molecule of pharmacological interest on model systems which recapitulate some of the main properties of the biological plasma membranes. In this work we studied the effect of a neurosteroid, Allopregnanolone (3α,5α-tetrahydroprogesterone or Allo), on a model bilayer composed by the ternary lipid mixture DOPC/bSM/chol.

Design, stereoselective synthesis, configurational stability and biological activity of 7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide.

Chiral 5-arylbenzothiadiazine derivatives have recently attracted particular attention because they exhibit an interesting pharmacological activity as AMPA receptor (AMPAr) positive modulators. However, investigations on their configurational stability suggest a rapid enantiomerization in physiological conditions. In order to enhance configurational stability, preserving AMPAr activity, we have designed the novel compound (R,S)-7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide bearing a pyrrolo moiety coupled with the 5-(furan-3-yl) substituent on benzothiadiazine core.

Simultaneous determination of pregnenolone sulphate, dehydroepiandrosterone and allopregnanolone in rat brain areas by liquid chromatography-electrospray tandem mass spectrometry.

Neurosteroids (NSs) are well known modulators of neuronal activity and by binding to different neuronal receptors are responsible for a broad spectrum of biological and pathophysiological conditions. Here, a sensitive liquid chromatographic-electrospray ionization-tandem mass spectrometric method (LC-ESI-MS/MS) has been developed and validated for the simultaneous determination in rat brain areas of three NSs, i.e.

Novel modulatory effects of neurosteroids and benzodiazepines on excitatory and inhibitory neurons excitability: a multi-electrode array recording study.

The balance between glutamate- and GABA-mediated neurotransmission in the brain is fundamental in the nervous system, but it is regulated by the "tonic" release of a variety of endogenous factors. One such important group of molecules are the neurosteroids (NSs) which, similarly to benzodiazepines (BDZs), enhance GABAergic neurotransmission. The purpose of our work was to investigate, at in vivo physiologically relevant concentrations, the effects of NSs and BDZs as GABA modulators on dissociated neocortical neuron networks grown in long-term culture.

5-Arylbenzothiadiazine Type Compounds as Positive Allosteric Modulators of AMPA/Kainate Receptors.

The potential therapeutic benefit of compounds able to activate AMPA receptors (AMPAr) has led to the search for new AMPAr positive modulators. On the basis of crystallographic data of the benzothiadiazines binding mode in the S1S2 GluA2 dimer interface, a set of 5-aryl-2,3-dihydrobenzothiadiazine type compounds has been synthesized and tested. Electrophysiological results suggested that 5-heteroaryl substituents on the benzothiadiazine core like 3-furanyl and 3-thiophenyl dramatically enhance the activity as positive modulators of AMPAr with respect to IDRA21 and cyclothiazide.

Molecular modeling studies, synthesis, configurational stability and biological activity of 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide.

The potential therapeutic benefit of compounds able to activate AMPA receptors (AMPArs) has led to a search for new AMPAr positive modulators. Among them, 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide (1) has attracted particular attention, because it is one of the most active benzothiadiazine-derived positive modulators of the AMPA receptor. It possesses two stereogenic centers, C3 and C6, thus it can exist as four stereoisomers.

Thyroid hormones modulate GABA(A) receptor-mediated currents in hippocampal neurons.

Thyroid hormones (THs) play a crucial role in the maturation and functioning of mammalian central nervous system. Thyroxine (T4) and 3, 3', 5-L-triiodothyronine (T3) are well known for their genomic effects, but recently attention has been focused on their non genomic actions as modulators of neuronal activity. In the present study we report that T4 and T3 reduce, in a non competitive manner, GABA-evoked currents in rat hippocampal cultures with IC₅₀s of 13±4μM and 12±3μM, respectively.

Evidence that isopropylthioxanthone (ITX) is devoid of anxiolytic and sedative effect.

Isopropylthioxanthone (ITX) is a well-known photo-initiator in ultraviolet light-cured inks frequently used in milk packaging materials, yoghurt, ready-to-feed infant formula, and other drinks. Traces of ITX have been found in milk and, as a consequence, there was considerable interest in studying the biological activity of this molecule and its potential hazard for the human health. Although the ITX genotoxic effects have been excluded by the European Food Safety Authority (EFSA), the US Environmental Protection Agency (USEPA) is still examining its possible toxic potential depending on a dose-effect ratio.

A novel class of allosteric modulators of AMPA/Kainate receptors.

The rapid hydrolysis in vivo of IDRA21 to 2-amino-5-chlorobenzensulfonamide has been demonstrated by microdialysis experiments. The IDRA21 metabolite possess in vitro a biological activity similar to that of IDRA21 itself. Taking 2-amino-5-chlorobenzensulfonamide as lead compound, a novel class of AMPAR positive allosteric modulators has been prepared.

Nongenomic regulation of glutamatergic neurotransmission in hippocampus by thyroid hormones.

Thyroid hormones (THs) are well known for their genomic effects but recently attention has focused also on their nongenomic actions as rapid modulators of membrane receptors. Here we show that thyroxine (T4) and 3,3',5'-l-triiodothyronine (T3) rapidly decrease N-methyl-d-aspartate (NMDA)-evoked currents in rat hippocampal cultures with potency in the micromolar range. The effect is not mediated by glutamate or glycine binding sites as an increase in agonist or glycine concentration does not alter TH potencies.

GABA(A) receptor neurotransmission dysfunction in a mouse model of social isolation-induced stress: possible insights into a non-serotonergic mechanism of action of SSRIs in mood and anxiety disorders.

Protracted social isolation in laboratory animals causes stress, which induces a variety of behavioral abnormalities including increased aggressiveness, anxiety-related behaviors, cognitive deficits and hyper locomotion. Many of these disorders are similar to the symptoms found in psychiatric disorders, such as depression, anxiety, premenstrual dysphoria and posttraumatic stress disorders (PTSD). Recent studies have demonstrated that male mice that have been socially isolated for more than 4 weeks show: (a) reduced responsiveness of GABA(A) receptors (GABA(A)-R) to the administrations of GABA mimetic drugs at GABA(A)-R; (b) downregulated biosynthesis of 3alpha,5alpha-tetrahydroprogesterone (3alpha,5alpha-THP) (allopregnanolone: ALLO), a neurosteroid with a potent positive allosteric modulatory effect on the action of GABA on GABA(A)-R; and (c) alterations in the expression of GABA(A)-R subunits (i.

Evidence that the beta-acids fraction of hops reduces central GABAergic neurotransmission.

Humulus lupulus (hops) is traditionally used as a tranquilizing herbal remedy. Here, we investigated the in vivo and in vitro effect of hop beta-acids on central nervous system function. Oral administration of beta-acids (5-10mg/kg) in rats produced an increased exploratory activity in the open field, a reduction in the pentobarbital hypnotic activity and a worsening of picrotoxin-induced seizures.

Functional in vitro characterization of CR 3394: a novel voltage dependent N-methyl-D-aspartate (NMDA) receptor antagonist.

Using the patch-clamp technique, we studied the effect of two novel adamantane derivatives, N-[2-(3,5-dimethyl-1-adamantyl)ethyl] guanidine (CR 3391) and N-[2-(3,5-dimethyl-1-adamantyl) ethyl]acetamidine (CR 3394), on NMDA receptors expressed in cortical neuron cultures. Our data show that CR 3391 and CR 3394 reduce NMDA-evoked currents (IC50 = 1.7 +/- 0.

Social isolation stress-induced aggression in mice: a model to study the pharmacology of neurosteroidogenesis.

Long-term social isolation of laboratory animals is a model to study the behavioral and neurochemical consequences of the absence of social interaction in rodents. Many of the symptoms induced by isolation resemble depression and anxiety disorder symptomatology. Our studies have revealed that male mice socially isolated for more than 4 weeks, exhibit increased aggressiveness, a reduced responsiveness to GABA(A) receptor acting drugs, and a downregulation of brain levels of 3alpha,5alpha-tetrahydroprogesterone (allopregnanolone: 3alpha,5alpha-THP), a neurosteroid endowed with potent positive allosteric modulatory activity of the action of GABA at various GABA(A) receptor subtypes.

Apigenin modulates GABAergic and glutamatergic transmission in cultured cortical neurons.

Using the patch-clamp technique, we studied the modulation of ionotropic gamma-aminobutyric acid (GABA) and glutamate neurotransmission by apigenin, a flavonoid with sedative and antidepressant activity. Apigenin reversibly reduced GABA-evoked currents mediated by alpha1beta2gamma2 receptors expressed in HEK293 cells. Amplitude and frequency of spontaneous postsynaptic inhibitory currents (sIPSCs) mediated by GABA(A) receptors were also decreased by apigenin in cultured cortical neurons.

Design of 1-substituted 2-arylmethyl-4,5-methylenedioxybenzene derivatives as antiseizure agents.

A series of 1-substituted 2-[(4-aryl)-methyl]-4,5-methylenedioxybenzene derivatives (13-25), structurally related to model compound 5 (2-[(4-aminophenyl)-(4-methylsemicarbazono)-methyl]-4,5-methylenedioxyphenylacetic acid methyl ester), were synthesized and tested as anticonvulsant agents in DBA/2 mice against sound-induced seizures. The new compounds possess anticonvulsant properties lower than those of prototype 5 but, in some instances, comparable to that of GYKI 52466, a well-known noncompetitive AMPA receptor antagonist.

IDRA-21, a positive AMPA receptor modulator, inhibits synaptic and extrasynaptic NMDA receptor mediated events in cultured cerebellar granule cells.

IDRA-21 (7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide) reduces alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) receptors desensitisation in vitro and restores learning and cognitive impairment in vivo. In this study, we show that in cerebellar granule cells (CGCs) in culture IDRA-21 reduces N-methyl-d-aspartate receptor (NMDAR) whole-cell currents. The effect is neither competitive nor voltage-dependent.

On the putative physiological role of allopregnanolone on GABA(A) receptor function.

To obtain definitive evidence for a physiological allosteric modulatory role for endogenous brain ALLO on GABA(A) receptor function, we studied GABA(A) receptor activity under conditions in which the concentration of endogenous brain ALLO was decreased by about 80% for longer than 5 h following the administration of SKF 105111- 17beta-17-[bis (1methylethyl) amino carbonyl] androstane-3,5-diene-3-carboxylic acid (SKF), a potent inhibitor of 5alpha-reductases Type I and II. We used the in situ patch-clamp technique to record GABA-evoked currents and spontaneous inhibitory postsynaptic currents (sIPSCs) from pyramidal neurons in neocortical slices of vehicle- or SKF-treated mice. The potency, but not the efficacy, of exogenously applied GABA was decreased in slices from mice treated with SKF.