Synthesis and Characterization of the Novel Rodent-Active and CNS-Penetrant P2X7 Receptor Antagonist Lu AF27139.

There remains an insufficient number of P2X7 receptor antagonists with adequate rodent potency, CNS permeability, and pharmacokinetic properties from which to evaluate CNS disease hypotheses preclinically. Herein, we describe the molecular pharmacology, safety, pharmacokinetics, and functional CNS target engagement of Lu AF27139, a novel rodent-active and CNS-penetrant P2X7 receptor antagonist. Lu AF27139 is highly selective and potent against rat, mouse, and human forms of the receptors.

Effects of the 5-HT receptor antagonist idalopirdine on extracellular levels of monoamines, glutamate and acetylcholine in the rat medial prefrontal cortex.

Idalopirdine (Lu AE58054) is a high affinity and selective antagonist for the human serotonin 5-HT receptor (K 0.83nM) in phase III development for mild-to-moderate Alzheimer's disease as an adjunct therapy to acetylcholinesterase inhibitors (AChEIs). We have studied the effects of idalopirdine on extracellular levels of monoamines, glutamate and acetylcholine in the medial prefrontal cortex (mPFC) of freely-moving rats using microdialysis.

Task- and Treatment Length-Dependent Effects of Vortioxetine on Scopolamine-Induced Cognitive Dysfunction and Hippocampal Extracellular Acetylcholine in Rats.

Major depressive disorder (MDD) is a common psychiatric disorder that often features impairments in cognitive function, and these cognitive symptoms can be important determinants of functional ability. Vortioxetine is a multimodal antidepressant that may improve some aspects of cognitive function in patients with MDD, including attention, processing speed, executive function, and memory. However, the cause of these effects is unclear, and there are several competing theories on the underlying mechanism, notably including regionally-selective downstream enhancement of glutamate neurotransmission and increased acetylcholine (ACh) neurotransmission.

Histamine may contribute to vortioxetine's procognitive effects; possibly through an orexigenic mechanism.

Vortioxetine is a novel multimodal antidepressant that acts as a serotonin (5-HT)3, 5-HT7, and 5-HT1D receptor antagonist; 5-HT1B receptor partial agonist; 5-HT1A receptor agonist; and 5-HT transporter inhibitor in vitro. In preclinical and clinical studies vortioxetine demonstrates positive effects on cognitive dysfunction. Vortioxetine's effect on cognitive function likely involves the modulation of several neurotransmitter systems.

Psychological Stress Activates the Inflammasome via Release of Adenosine Triphosphate and Stimulation of the Purinergic Type 2X7 Receptor.

Background: The mechanisms underlying stress-induced inflammation that contribute to major depressive disorder are unknown. We examine the role of the adenosine triphosphate (ATP)/purinergic type 2X7 receptor (P2X7R) pathway and the NLRP3 (nucleotide-binding, leucine-rich repeat, pyrin domain containing 3) inflammasome in interleukin (IL)-1β and depressive behavioral responses to stress.

Methods: The influence of acute restraint stress on extracellular ATP, glutamate, IL-1β, and tumor necrosis factor alpha in hippocampus was determined by microdialysis, and the influence of acute restraint stress on the NLRP3 inflammasome was determined by western blot analysis.

Effects of serotonin in the hippocampus: how SSRIs and multimodal antidepressants might regulate pyramidal cell function.

The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there.

Serotonergic Regulation of Prefrontal Cortical Circuitries Involved in Cognitive Processing: A Review of Individual 5-HT Receptor Mechanisms and Concerted Effects of 5-HT Receptors Exemplified by the Multimodal Antidepressant Vortioxetine.

It has been known for several decades that serotonergic neurotransmission is a key regulator of cognitive function, mood, and sleep. Yet with the relatively recent discoveries of novel serotonin (5-HT) receptor subtypes, as well as an expanding knowledge of their expression level in certain brain regions and localization on certain cell types, their involvement in cognitive processes is still emerging. Of particular interest are cognitive processes impacted in neuropsychiatric and neurodegenerative disorders.

Derivatization for the simultaneous LC/MS quantification of multiple neurotransmitters in extracellular fluid from rat brain microdialysis.

Quantification of amino acid based neurotransmitters in extracellular fluids, such as those in the neuron synapse, presents a challenge to the analytical chemistry because of the absence of UV- or fluorescence-detectable functional groups and the low sensitivity in mass spectrometric detection. This report describes a novel use of the succinimide reagent, N-α-Boc-l-tryptophan hydroxysuccinimide ester (Boc-TRP), for the pre-column derivatization to simultaneously quantify multiple neurotransmitters in the rat brain microdialysis samples. The Boc-TRP derivatization was rapid and quantitative in phosphate the buffer (pH 7.

Qualification of LSP1-2111 as a Brain Penetrant Group III Metabotropic Glutamate Receptor Orthosteric Agonist.

LSP1-2111 is a group III metabotropic glutamate receptor agonist with preference toward the mGlu4 receptor subtype. This compound has been extensively used as a tool to explore the pharmacology of mGlu4 receptor activation in preclinical animal behavioral models. However, the blood-brain barrier penetration of this amino acid derivative has never been studied.

Vortioxetine, but not escitalopram or duloxetine, reverses memory impairment induced by central 5-HT depletion in rats: evidence for direct 5-HT receptor modulation.

Depressed patients suffer from cognitive dysfunction, including memory deficits. Acute serotonin (5-HT) depletion impairs memory and mood in vulnerable patients. The investigational multimodal acting antidepressant vortioxetine is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, 5-HT1B receptor partial agonist, 5-HT1A receptor agonist and 5-HT transporter (SERT) inhibitor that enhances memory in normal rats in novel object recognition (NOR) and conditioned fear (Mørk et al.

Preclinical pharmacology of AZD2327: a highly selective agonist of the δ-opioid receptor.

In the present article, we summarize the preclinical pharmacology of 4-{(R)-(3-aminophenyl)[4-(4-fluorobenzyl)-piperazin-1-yl]methyl}-N,N-diethylbenzamide (AZD2327), a highly potent and selective agonist of the δ-opioid receptor. AZD2327 binds with sub-nanomolar affinity to the human opioid receptor (K(i) = 0.49 and 0.

Immediate and sustained improvements in working memory after selective stimulation of α7 nicotinic acetylcholine receptors.

Background: Nicotine improves cognition in humans and animal models of neuropsychiatric disorders. Here, we sought to establish whether selective stimulation of the neuronal nicotinic α7 receptor could improve spatial working memory in nonhuman primates.

Methods: Beginning with an estimated dose range from rodent studies, the dose of the α7 agonist AZD0328 was titrated for a significant impact on working memory in rhesus macaques after acute administration.

Self-administered and passive cocaine infusions produce different effects on corticosterone concentrations in the medial prefrontal cortex (MPC) of rats.

Although our lab, as well as several others, has demonstrated a role for corticosterone in cocaine self-administration, there are no studies of the central dynamics of this hormone over the course of a behavioral session when rats are self-administering cocaine or receiving passive injections. The assay of corticosterone in microdialysates collected during such sessions allows for determinations of changes in brain corticosterone during drug-taking behavior. By using the combination of microdialysis in terminal fields for the mesocorticolimbic dopaminergic system and the yoked-triad model, one can distinguish between the direct cocaine-induced activation of the hypothalamo-pituitary-adrenal (HPA) axis from the activation of the HPA axis related to drug-taking.

Selective alpha7 nicotinic receptor activation by AZD0328 enhances cortical dopamine release and improves learning and attentional processes.

AZD0328, a novel spirofuropyridine neuronal nicotinic receptor partial agonist, was used to investigate the role of alpha7 neuronal nicotinic receptor (NNR) activation in the modulation of midbrain dopamine neuron function, cortical dopamine release and on two behavioral tasks known to be dependent on optimal levels of cortical dopamine. In vivo recordings from area 10 (ventral tegmental area) in rat brain showed an increased firing of putative dopamine neurons in response to low (0.00138 mg/kg) doses of AZD0328.

Effects of corticotropin-releasing hormone receptor antagonists on cocaine-induced dopamine overflow in the medial prefrontal cortex and nucleus accumbens of rats.

Recent evidence suggests an important role for corticotropin-releasing hormone (CRH) and CRH receptors in cocaine reinforcement. CRH receptor antagonists reduce cocaine self-administration and attenuate the reinstatement of extinguished cocaine-seeking behavior, but little is known about the mechanisms involved. One possible mechanism for these effects may involve the cocaine-induced activation of CRH located in brain regions outside of the hypothalamus.

Effects of acute and chronic ketoconazole administration on hypothalamo--pituitary--adrenal axis activity and brain corticotropin-releasing hormone.

We have been investigating the effects of ketoconazole on cocaine reward in rats for several years now. However, we recently confirmed that ketoconazole-induced changes in cocaine self-administration and reinstatement do not always correspond with decreases in plasma corticosterone, which suggests that other mechanisms must be underlying the behavioral effects that we observe. This experiment was therefore designed to determine the effects of acute, repeated and chronic ketoconazole administration on corticotropin-releasing hormone (CRH) content in hypothalamic and extra-hypothalamic brain sites in rats following the same dosing regimen that we use in our behavioral studies.

Changes in rat adipocyte and liver glucose metabolism following repeated restraint stress.

Rats exposed to repeated restraint weigh less than controls even 8 weeks after stress. Stress-induced weight loss is lean tissue, but the post-stress difference in weight between control and restrained rats is lean and fat mass. Whole-body glucose clearance is enhanced 1 day after stress, but adipocyte glucose utilization is inhibited and muscle glucose transport is unchanged.

The role of CRH in behavioral responses to stress.

Corticotropin-releasing hormone (CRH) and urocortin in the central nervous system affect behavior and can enhance behavioral responses to stressors. The action of CRH-related peptides is mediated through multiple receptors that differ markedly in their pharmacological profiles and anatomical distribution. Comparative pharmacology of CRH receptor agonists suggests that CRH, urocortin, sauvagine and urotensin consistently mimic, and CRH receptor antagonists consistently lessen, functional consequences of stressor exposure.

The role of CRF receptor subtypes in stress-induced behavioural responses.

The actions of corticotropin-releasing factor (CRF) and CRF-related peptides in the brain and periphery are mediated through multiple receptors. Two CRF receptor subtypes that differ markedly in their pharmacological profiles and anatomical distribution have been identified and characterized. Important advances have been made in understanding CRF and its actions through the development of specific CRF receptor antagonists, application of antisense oligonucleotides, and the production of transgenic mice lacking functional CRF(1) receptors.

The effects of paradoxical sleep deprivation and valine on spatial learning and brain 5-HT metabolism.

We have previously reported that rapid eye movement sleep deprivation (REMSD), induced by the flower pot technique, causes a deficit in reference spatial memory and increases rates of serotonin (5-HT) metabolism in the brain. In this study we used increased concentrations of dietary valine to inhibit tryptophan (TRP) transport across the blood-brain barrier in an attempt to modify the REMSD-induced increase of 5-HT metabolism. Rats were fed either a control diet or the same diet supplemented to 2% by weight valine, and were allocated to one of three experimental groups: cage control (CC), stress tank control (TC), or REMSD.

Prevention of stress-induced weight loss by third ventricle CRF receptor antagonist.

We previously reported that rats exposed to repeated restraint (3 h/day for 3 days) experience temporary hypophagia and a sustained reduction in body weight compared with nonrestrained controls. Studies described here determined the involvement of central corticotropin-releasing factor (CRF) receptors in the initiation of this chronic response to acute stress. In experiment 1, Sprague-Dawley rats were fitted with cannulas in the lateral ventricle and infused with 50 micrograms of alphahCRF-(9-41) or saline immediately before restraint on each of the 3 days of restraint.

Effect of repeated stress on body weight and body composition of rats fed low- and high-fat diets.

Exposure to the moderate stressor of 3-h restraint for 3 consecutive days causes a temporary drop in food intake but a permanent reduction in body weight in adult rats. Young rats did not show the same response. Food intake of adult rats exposed to repeated restraint was significantly lower than that of controls for 4 days after the end of stress, and there was no rebound hyperphagia.

The role of CRF2 receptors in corticotropin-releasing factor- and urocortin-induced anorexia.

The experiments presented in this study were designed to assess corticotropin-releasing factor (CRF) receptor subtype mediation of CRF- and urocortin (UCN)-induced decrease in food intake. Male Sprague-Dawley rats were treated with antisense and sense oligonucleotides (ON) to CRF2 receptor mRNAs for 36 h and then received an intracerebroventricular (i.c.

Cortical catecholamine secretion following intravenous nitroprusside infusion: a voltammetric study.

Intravenous administration of sodium nitroprusside (NP) decreases blood pressure and activates noradrenergic neurons in the locus coeruleus (LC). Microdialysis studies have shown that NP infusion is accompanied by increased extracellular concentrations of norepinephrine (NE) in the medial prefrontal cortex. The present study used in vivo voltammetry to obtain a finer temporal analysis of the NP-induced changes in the extracellular concentrations of catecholamine-like compounds in the LC terminal fields in the rat medial prefrontal cortex.