The impact of mGlu2 or mGlu5 receptor activators on the production of L-arginine derivatives and the expression of PMRT5 or DDAH1 enzymes in animal models of cognitive decline.

L-arginine derivatives (ADMA, SDMA, NMMA) are endogenous inhibitors of nitric oxide (NO֗) production, which is essential in critical brain processes including blood-brain barrier (BBB) integrity and long-term potentiation (LTP). ADMA and NMMA are degraded by dimethylarginine dimethylaminohydrolase 1 (DDAH1) and protein arginine methyltransferase 5 (PRMT5) is an emerging epigenetic enzyme that mainly represses transcription of target genes via symmetric dimethylation of arginine residues. There is no data concerning the impact of metabotropic glutamate receptors (mGlu) ligands on this aspect of brain physiology.

Prevention of MK-801-induced amnestic effect with combined activation of 5-HT and muscarinic receptors in mice.

Background: Muscarinic or 5-HT receptors are crucial in learning and memory processes, and their expression is evident in the brain areas involved in cognition. The administration of the activators of these receptors prevents the development of cognitive dysfunctions in animal models of schizophrenia induced by MK-801 (N-methyl-d-aspartate receptor antagonist) administration. GABAergic dysfunction is considered as one of the most important causes of MK-801-induced spatial learning deficits.

The Impact of LY487379 or CDPPB on eNOS Expression in the Mouse Brain and the Effect of Joint Administration of Compounds with NO Releasers on MK-801- or Scopolamine-Driven Cognitive Dysfunction in Mice.

The role of endothelial nitric oxide synthase (eNOS) in the regulation of a variety of biological processes is well established, and its dysfunction contributes to brain pathologies, including schizophrenia or Alzheimer's disease (AD). Positive allosteric modulators (PAMs) of metabotropic glutamate (mGlu) receptors were shown to be effective procognitive compounds, but little is known about their impact on eNOS expression and stability. Here, we investigated the influence of the acute and chronic administration of LY487379 or CDPPB (mGlu2 and mGlu5 PAMs), on eNOS expression in the mouse brain and the effect of the joint administration of the ligands with nitric oxide (NO) releasers, spermineNONOate or DETANONOate, in different combinations of doses, on MK-801- or scopolamine-induced amnesia in the novel object recognition (NOR) test.

Activation of Metabotropic Glutamate Receptor (mGlu) and Muscarinic Receptors (M, M, and M), Alone or in Combination, and Its Impact on the Acquisition and Retention of Learning in the Morris Water Maze, NMDA Expression and cGMP Synthesis.

The Morris water maze (MWM) is regarded as one of the most popular tests for detecting spatial memory in rodents. Long-term potentiation and cGMP synthesis seem to be among the crucial factors involved in this type of learning. Muscarinic (M, M, and M receptors) and metabotropic glutamate (mGlu) receptors are important targets in the search for antipsychotic drugs with the potency to treat cognitive disabilities associated with the disorder.

Prenatal stress aggravates age-dependent cognitive decline, insulin signaling dysfunction, and the pro-inflammatory response in the APP mouse model of Alzheimer's disease.

Accumulating evidence indicates that early adverse life experiences may be involved in the pathogenesis of Alzheimer's disease (AD). Prenatal stress (PS) can affect brain maturation and neuroimmune and metabolic interactions, leading to age-dependent cognitive deficits in offspring. However, a multi-faceted cause-and-effect impact of PS on the development of cognitive deficits in the process of physiological ageing and in the APP mouse model of Alzheimer's disease has not yet been evaluated.

A Comparative Study of the Impact of NO-Related Agents on MK-801- or Scopolamine-Induced Cognitive Impairments in the Morris Water Maze.

Learning and memory deficits accompany numerous brain dysfunctions, including schizophrenia and Alzheimer's disease (AD), and many studies point to the role of nitric oxide (NO) in these processes. The present investigations constitute the follow-up of our previous research, in which we investigated the activity of NO releasers and a selective inhibitor of neuronal NO synthase (nNOS) to prevent short-term memory deficits in novel object recognition and T-maze. Here, the ability of the compounds to prevent the induction of long-term memory deficits by MK-801 or scopolamine administration was investigated.

Endothelial dysfunction due to eNOS uncoupling: molecular mechanisms as potential therapeutic targets.

Nitric oxide (NO) is one of the most important molecules released by endothelial cells, and its antiatherogenic properties support cardiovascular homeostasis. Diminished NO bioavailability is a common hallmark of endothelial dysfunction underlying the pathogenesis of the cardiovascular disease. Vascular NO is synthesized by endothelial nitric oxide synthase (eNOS) from the substrate L-arginine (L-Arg), with tetrahydrobiopterin (BH) as an essential cofactor.

Design and Synthesis of New Quinazolin-4-one Derivatives with Negative mGlu Receptor Modulation Activity and Antipsychotic-Like Properties.

Following the glutamatergic theory of schizophrenia and based on our previous study regarding the antipsychotic-like activity of mGlu NAMs, we synthesized a new compound library containing 103 members, which were examined for NAM mGlu activity in the T-REx 293 cell line expressing a recombinant human mGlu receptor. Out of the twenty-two scaffolds examined, active compounds were found only within the quinazolinone chemotype. 2-(2-Chlorophenyl)-6-(2,3-dimethoxyphenyl)-3-methylquinazolin-4(3)-one (, , mGlu IC = 6.

The mGlu receptor in schizophrenia - An update and future perspectives.

The mGlu receptor belongs to the III group of metabotropic glutamatergic (mGlu) receptors and physiologically serves as an "emergency" receptor that is activated by high, almost pathological, glutamate concentrations. Of all mGlu receptors, this receptor is most highly expressed in the brain. Additionally, relatively intense expression of the receptor was found at the periphery, for example in the bowels or in the reproductive system of male mice, but this review will be focused predominantly on its role in the brain.

Procognitive activity of nitric oxide inhibitors and donors in animal models.

Nitric oxide is a small gaseous molecule that plays important roles in the majority of biological functions. Impairments of NO-related pathways contribute to the majority of neurological disorders, such as Alzheimer's disease (AD), and mental disorders, such as schizophrenia. Cognitive decline is one of the most serious impairments accompanying both AD and schizophrenia.

New 1,2,4-oxadiazole derivatives with positive mGlu receptor modulation activity and antipsychotic-like properties.

Considering the allosteric regulation of mGlu receptors for potential therapeutic applications, we developed a group of 1,2,4-oxadiazole derivatives that displayed mGlu receptor positive allosteric modulatory activity (EC = 282-656 nM). Selectivity screening revealed that they were devoid of activity at mGlu, mGlu and mGlu receptors, but modulated mGlu and mGlu receptors, thus were classified as group III-preferring mGlu receptor agents. None of the compounds was active towards hERG channels or in the mini-AMES test.

Nitric Oxide-Dependent Mechanisms Underlying MK-801- or Scopolamine-Induced Memory Dysfunction in Animals: Mechanistic Studies.

MK-801, an NMDA receptor antagonist, and scopolamine, a cholinergic receptor blocker, are widely used as tool compounds to induce learning and memory deficits in animal models to study schizophrenia or Alzheimer-type dementia (AD), respectively. Memory impairments are observed after either acute or chronic administration of either compound. The present experiments were performed to study the nitric oxide (NO)-related mechanisms underlying memory dysfunction induced by acute or chronic (14 days) administration of MK-801 (0.

Serotonergic-Muscarinic Interaction within the Prefrontal Cortex as a Novel Target to Reverse Schizophrenia-Related Cognitive Symptoms.

Recent studies revealed that the activation of serotonergic 5-HT and muscarinic M, M, or M receptors prevent MK-801-induced cognitive impairments in animal models. In the present study, the effectiveness of the simultaneous activation of 5-HT and muscarinic receptors at preventing MK-801-induced cognitive deficits in novel object recognition (NOR) or Y-maze tests was investigated. Activators of 5-HT (F15599), M (VU0357017), M (VU0152100), or M (VU0238429) receptors administered at top doses for seven days reversed MK-801-induced deficits in the NOR test, similar to the simultaneous administration of subeffective doses of F15599 (0.

Nitric Oxide-Dependent Pathways as Critical Factors in the Consequences and Recovery after Brain Ischemic Hypoxia.

Brain ischemia is one of the leading causes of disability and mortality worldwide. Nitric oxide (NO), a molecule that is involved in the regulation of proper blood flow, vasodilation, neuronal and glial activity constitutes the crucial factor that contributes to the development of pathological changes after stroke. One of the early consequences of a sudden interruption in the cerebral blood flow is the massive production of reactive oxygen and nitrogen species (ROS/RNS) in neurons due to NO synthase uncoupling, which leads to neurotoxicity.

Neurochemical changes underlying cognitive impairment in olfactory bulbectomized rats and the impact of the mGlu-positive allosteric modulator CDPPB.

The olfactory bulbectomized (OBX) rat model is a well-established model of depression in which antidepressant drugs reverse deficits in the passive avoidance test 14 days after administration. Recently, the olfactory bulbectomized rat model has been proposed to be a model of Alzheimer's disease (AD), and the available data indicate similarities between the changes that typically occur in AD and those observed in OBX animals. In the present study, the occurrence of neurochemical impairments related to AD were investigated 8 months after OB ablation.

Regulation of Glutamatergic Activity via Bidirectional Activation of Two Select Receptors as a Novel Approach in Antipsychotic Drug Discovery.

Schizophrenia is a mental disorder that affects approximately 1-2% of the population and develops in early adulthood. The disease is characterized by positive, negative, and cognitive symptoms. A large percentage of patients with schizophrenia have a treatment-resistant disease, and the risk of developing adverse effects is high.

The Trace Kynurenine, Cinnabarinic Acid, Displays Potent Antipsychotic-Like Activity in Mice and Its Levels Are Reduced in the Prefrontal Cortex of Individuals Affected by Schizophrenia.

Cinnabarinic acid (CA) is a kynurenine metabolite that activates mGlu4 metabotropic glutamate receptors. Using a highly sensitive ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS-MS) method, we found that CA is present in trace amounts in human brain tissue. CA levels were largely reduced in the prefrontal cortex (PFC) of individuals affected by schizophrenia.

Simultaneous activation of mGlu and muscarinic receptors reverses MK-801-induced cognitive decline in rodents.

The activity of an allosteric agonist of muscarinic M receptor, VU0357017, and a positive allosteric modulator (PAM) of M receptor, VU0238429, were investigated alone or in combination with the mGlu receptor PAM, LY487379 using the following behavioural tests: prepulse inhibition (PPI), novel object recognition (NOR), and spatial delayed alternation (SDA). VU0357017 (10 and 20 mg/kg) and VU0238429 (5 and 10 mg/kg) reversed deficits in PPI while VU0238429 (2.5 and 5 mg/kg) was effective in SDA.

Reversal of MK-801-Induced Disruptions in Social Interactions and Working Memory with Simultaneous Administration of LY487379 and VU152100 in Mice.

Negative and cognitive symptoms of schizophrenia contribute to an impaired social and professional life for schizophrenic patients, and in most cases, these symptoms are treatment resistant. Therefore, identification of new treatment strategies is sorely needed. Metabotropic glutamate receptors (mGlu) and muscarinic (M) receptors for acetylcholine have been considered promising targets for novel antipsychotics.

Search for a 5-CT alternative. and evaluation of novel pharmacological tools: 3-(1-alkyl-1-imidazol-5-yl)-1-indole-5-carboxamides, low-basicity 5-HT receptor agonists.

Close structural analogues of 5-carboxamidotryptamine (5-CT) based on the newly discovered indole-imidazole scaffold were synthesized and evaluated to search for a 5-HT receptor agonist of higher selectivity. drug-likeness studies and pharmacological evaluation of potent and selective low-basicity 5-HT receptor agonists, previously published (3-(1-ethyl-1-imidazol-5-yl)-1-indole-5-carboxamide, AH-494) and (3-(1-methyl-1-imidazol-5-yl)-1-indole-5-carboxamide), have supported their usefulness as pharmacological tools. Comprehensive comparison studies between , and the commonly used 5-CT showed their very similar ADMET properties.

Simultaneous activation of muscarinic and GABA receptors as a bidirectional target for novel antipsychotics.

Recent preclinical studies point to muscarinic and GABA receptors as novel therapeutic targets for the treatment of schizophrenia. This study was aimed to assess the role of muscarinic and GABA receptor interactions in animal models of schizophrenia, using positive allosteric modulators (PAMs) of GABA receptor (GS39783), muscarinic M (VU0152100) and M (VU0238429) receptor, and partial allosteric agonist of M receptor (VU0357017). DOI-induced head twitches, social interaction and novel object recognition tests were used as the models of schizophrenia.

Depression and schizophrenia viewed from the perspective of amino acidergic neurotransmission: Antipodes of psychiatric disorders.

Depression and schizophrenia are burdensome, costly serious and disabling mental disorders. Moreover the existing treatments are not satisfactory. As amino-acidergic (AA) neurotransmitters built a vast majority of brain neurons, in this article we plan to focus on drugs influencing AA neurotransmission in both diseases: we will discuss several facts concerning glutamatergic and GABA-ergic neurotransmission in these diseases, based mainly on preclinical experiments that used stimulators and/or blockers of both neurotransmitter systems.

Mutual activation of glutamatergic mGlu and muscarinic M receptors reverses schizophrenia-related changes in rodents.

Rationale: Metabotropic glutamate receptors and muscarinic M receptors have been proposed as novel targets for various brain disorders, including schizophrenia. Both receptors are coupled to G proteins and are expressed in brain circuits that are important in schizophrenia. Therefore, their mutual activation may be an effective treatment and allow minimizing the doses of ligands required for optimal activity.

Neurochemical changes underlying schizophrenia-related behavior in a modified forced swim test in mice.

The modified forced swim test (MFST) has excellent predictive validity for investigating the antipsychotic activity of drugs, with particular emphasis on their activity toward negative symptoms of schizophrenia. However, its face and construct validity are less understood. Therefore, in the present study, some biochemical changes within GABAergic and serotonergic neurotransmission that could be related to observed MK-801-induced disturbances and the activity of compounds active at those neurotransmitters were investigated.