Behavioural phenotypic characterization of CD-1 mice lacking the neuropeptide S receptor

Efferent projections of Nps-expressing neurons in the parabrachial region

In the brain, connectivity determines function. Neurons in the parabrachial nucleus (PB) relay diverse information to widespread brain regions, but the connections and functions of PB neurons that express Nps (neuropeptide S, NPS) remain mysterious. Here, we use Cre-dependent anterograde tracing and whole-brain analysis to map their output connections. While many other PB neurons project ascending axons through the central tegmental tract, NPS axons reach the forebrain via distinct periventricular and ventral pathways. Along the periventricular pathway, NPS axons target the tectal longitudinal column and periaqueductal gray, then continue rostrally to target the paraventricular nucleus of the thalamus. Along the ventral pathway, NPS axons blanket much of the hypothalamus but avoid the ventromedial and mammillary nuclei. They also project prominently to the ventral bed nucleus of the stria terminalis, A13 cell group, and magnocellular subparafasciular nucleus. In the hindbrain, NPS axons have fewer descending projections, targeting primarily the superior salivatory nucleus, nucleus of the lateral lemniscus, and periolivary region. Combined with what is known already about NPS and its receptor, the output pattern of Nps-expressing neurons in the PB region predicts roles in threat response and circadian behavior.

Pathophysiological and therapeutic implications of neuropeptide S system in neurological disorders

Neuropeptide S (NPS) is a 20 amino acids-containing neuroactive molecule discovered by the reverse pharmacology method. NPS is detected in specific brain regions like the brainstem, amygdala, and hypothalamus, while its receptor (NPSR) is ubiquitously expressed in the central nervous system (CNS). Besides CNS, NPS and NPSR are also expressed in the peripheral nervous system. NPSR is a G-protein coupled receptor that primarily uses Gq and Gs signaling pathways to mediate the actions of NPS. In animal models of Parkinsonism and Alzheimer's disease, NPS exerts neuroprotective effects. NPS suppresses oxidative stress, anxiety, food intake, and pain, and promotes arousal. NPSR facilitates reward, reinforcement, and addiction-related behaviors. Genetic variation and single nucleotide polymorphism in NPSR are associated with depression, schizophrenia, rheumatoid arthritis, and asthma. NPS interacts with several neurotransmitters including glutamate, noradrenaline, serotonin, corticotropin-releasing factor, and gamma-aminobutyric acid. It also modulates the immune system via augmenting pro-inflammatory cytokines and plays an important role in the pathogenesis of rheumatoid arthritis and asthma. In the present review, we discussed the distribution profile of NPS and NPSR, signaling pathways, and their importance in the pathophysiology of various neurological disorders. We have also proposed the areas where further investigations on the NPS system are warranted.

Diverse roles of pontine NPS-expressing neurons in sleep regulation

Neuropeptide S (NPS) was postulated to be a wake-promoting neuropeptide with unknown mechanism, and a mutation in its receptor (NPSR1) causes the short sleep duration trait in humans. We investigated the role of different NPS+ nuclei in sleep/wake regulation. Loss-of-function and chemogenetic studies revealed that NPS+ neurons in the parabrachial nucleus (PB) are wake-promoting, whereas peri-locus coeruleus (peri-LC) NPS+ neurons are not important for sleep/wake modulation. Further, we found that a NPS+ nucleus in the central gray of the pons (CGPn) strongly promotes sleep. Fiber photometry recordings showed that NPS+ neurons are wake-active in the CGPn and wake/REM-sleep active in the PB and peri-LC. Blocking NPS-NPSR1 signaling or knockdown of Nps supported the function of the NPS-NPSR1 pathway in sleep/wake regulation. Together, these results reveal that NPS and NPS+ neurons play dichotomous roles in sleep/wake regulation at both the molecular and circuit levels.

Neuropeptide S Receptor 1 variant (I107N) regulates behavioral characteristics and NPS effect in mice in a sex-dependent manner

Accumulated data demonstrate that the A/T single-nucleotide polymorphism (SNP) rs324981 in the human neuropeptide S receptor 1 (NPSR1) gene, resulting in an amino acid change from asparagine (N) to isoleucine (I) at position 107, is associated with susceptibility to psychiatric disorders. Neuropeptide S (NPS) has also been implicated in modulating these disorders in rodent experiments. However, the effect of this SNP on NPSR1 activity remains unclear. To elucidate the pathophysiological and pharmacological implications of this SNP, we generated a mouse model carrying the human-specific AA variant in NPSR1. This model exhibited sex-specific behavioral differences mirroring human observations, including fear response, anxiety, and depression. Notably, intracerebroventricular administration of NPS (1 nmol) significantly promoted locomotor activity and alleviated looming-stimulated fear and anxiety-like behaviors in NPSR TT mice, but not in NPSR AA mice. NPS also reduced depression-like behavior in a sex and genotype-dependent manner in the forced swim test. Our study in NPSR variant mice enhances our understanding of phenotypic and pharmacological differences due to the NPSR1 SNP, providing an animal model for further investigation of physiological processes in humans carrying this SNP.

Efferent projections of Nps-expressing neurons in the parabrachial region

In the brain, connectivity determines function. Neurons in the parabrachial nucleus (PB) relay diverse information to widespread brain regions, but the connections and functions of PB neurons that express Nps (neuropeptide S) remain mysterious. Here, we use Cre-dependent anterograde tracing and whole-brain analysis to map their output connections. While many other PB neurons project ascending axons through the central tegmental tract, NPS axons reach the forebrain via distinct periventricular and ventral pathways. Along the periventricular pathway, NPS axons target the tectal longitudinal column and periaqueductal gray then continue rostrally to target the paraventricular nucleus of the thalamus. Along the ventral pathway, NPS axons blanket much of the hypothalamus but avoid the ventromedial and mammillary nuclei. They also project prominently to the ventral bed nucleus of the stria terminalis, A13 cell group, and magnocellular subparafasciular nucleus. In the hindbrain, NPS axons have fewer descending projections, targeting primarily the superior salivatory nucleus, nucleus of the lateral lemniscus, and periolivary region. Combined with what is known about NPS and its receptor, the output pattern of Nps-expressing neurons in the PB region predicts a role in threat response and circadian behavior.

Peroxisome proliferator-activated receptor-α activation facilitates contextual fear extinction and modulates intrinsic excitability of dentate gyrus neurons

The dentate gyrus (DG) of the hippocampus encodes contextual information associated with fear, and cell activity in the DG is required for acquisition and extinction of contextual fear. However, the underlying molecular mechanisms are not fully understood. Here we show that mice deficient for peroxisome proliferator-activated receptor-α (PPARα) exhibited a slower rate of contextual fear extinction. Furthermore, selective deletion of PPARα in the DG attenuated, while activation of PPARα in the DG by local infusion of aspirin facilitated extinction of contextual fear. The intrinsic excitability of DG granule neurons was reduced by PPARα deficiency but increased by activation of PPARα with aspirin. Using RNA-Seq transcriptome we found that the transcription level of neuropeptide S receptor 1 (Npsr1) was tightly correlated with PPARα activation. Our results provide evidence that PPARα plays an important role in regulating DG neuronal excitability and contextual fear extinction.

Neuropeptide S Encodes Stimulus Salience in the Paraventricular Thalamus

Evaluation of stimulus salience is critical for any higher organism, as it allows for prioritizing of vital information, preparation of responses, and formation of valuable memory. The paraventricular nucleus of the thalamus (PVT) has recently been identified as an integrator of stimulus salience but the neurochemical basis and afferent input regarding salience signaling have remained elusive. Here we report that neuropeptide S (NPS) signaling in the PVT is necessary for stimulus salience encoding, including aversive, neutral and reinforcing sensory input. Taking advantage of a striking deficit of both NPS receptor (NPSR1) and NPS precursor knockout mice in fear extinction or novel object memory formation, we demonstrate that intra-PVT injections of NPS can rescue the phenotype in NPS precursor knockout mice by increasing the salience of otherwise low-intensity stimuli, while intra-PVT injections of NPSR1 antagonist in wild type mice partially replicates the knockout phenotype. The PVT appears to provide stimulus salience encoding in a dose- and NPS-dependent manner. PVT NPSR1 neurons recruit the nucleus accumbens shell and structures in the prefrontal cortex and amygdala, which were previously linked to the brain salience network. Overall, these results demonstrate that stimulus salience encoding is critically associated with NPS activity in the PVT.

Role of the Neuropeptide S System in Emotionality, Stress Responsiveness and Addiction-Like Behaviours in Rodents: Relevance to Stress-Related Disorders

The neuropeptide S (NPS) and its receptor (NPSR1) have been extensively studied over the last two decades for their roles in locomotion, arousal/wakefulness and anxiety-related and fear-related behaviours in rodents. However, the possible implications of the NPS/NPSR1 system, especially those of the single nucleotide polymorphism (SNP) rs324981, in stress-related disorders and substance abuse in humans remain unclear. This is possibly due to the fact that preclinical and clinical research studies have remained separated, and a comprehensive description of the role of the NPS/NPSR1 system in stress-relevant and reward-relevant endpoints in humans and rodents is lacking. In this review, we describe the role of the NPS/NPSR1 system in emotionality, stress responsiveness and addiction-like behaviour in rodents. We also summarize the alterations in the NPS/NPSR1 system in individuals with stress-related disorders, as well as the impact of the SNP rs324981 on emotion, stress responses and neural activation in healthy individuals. Moreover, we discuss the therapeutic potential and possible caveats of targeting the NPS/NPSR1 system for the treatment of stress-related disorders. The primary goal of this review is to highlight the importance of studying some rodent behavioural readouts modulated by the NPS/NPSR1 system and relevant to stress-related disorders.

Neuropeptide S Receptor as an Innovative Therapeutic Target for Parkinson Disease

Parkinson disease (PD) is a neurodegenerative disease mainly characterized by the loss of nigral dopaminergic neurons in the substantia nigra pars compacta. Patients suffering from PD develop severe motor dysfunctions and a myriad of non-motor symptoms. The treatment mainly consists of increasing central dopaminergic neurotransmission and alleviating motor symptoms, thus promoting severe side effects without modifying the disease’s progress. A growing body of evidence suggests a close relationship between neuropeptide S (NPS) and its receptor (NPSR) system in PD: (i) double immunofluorescence labeling studies showed that NPSR is expressed in the nigral tyrosine hydroxylase (TH)-positive neurons; (ii) central administration of NPS increases spontaneous locomotion in naïve rodents; (iii) central administration of NPS ameliorates motor and nonmotor dysfunctions in animal models of PD; (iv) microdialysis studies showed that NPS stimulates dopamine release in naïve and parkinsonian rodents; (v) central injection of NPS decreases oxidative damage to proteins and lipids in the rodent brain; and, (vi) 7 days of central administration of NPS protects from the progressive loss of nigral TH-positive cells in parkinsonian rats. Taken together, the NPS/NPSR system seems to be an emerging therapeutic strategy for alleviating motor and non-motor dysfunctions of PD and, possibly, for slowing disease progress.

Dissociative Effects of Neuropeptide S Receptor Deficiency and Nasal Neuropeptide S Administration on T-Maze Discrimination and Reversal Learning

Cognitive flexibility refers to the ability to modify learned behavior in response to changes in the environment. In laboratory rodents, cognitive flexibility can be assessed in reversal learning, i.e., the change of contingencies, for example in T-maze discrimination learning. The present study investigated the role of the neuropeptide S (NPS) system in cognitive flexibility. In the first experiment, mice deficient of NPS receptors (NPSR) were tested in T-maze discrimination and reversal learning. In the second experiment, C57BL/6J mice were tested in the T-maze after nasal administration of NPS. Finally, the effect of nasal NPS on locomotor activity was evaluated. NPSR deficiency positively affected the acquisition of T-maze discrimination but had no effects on reversal learning. Nasal NPS administration facilitated reversal learning and supported an allocentric learning strategy without affecting acquisition of the task or locomotor activity. Taken together, the present data show that the NPS system is able to modulate both acquisition of T-maze discrimination and its reversal learning. However, NPSR deficiency only improved discrimination learning, while nasal NPS administration only improved reversal learning, i.e., cognitive flexibility. These effects, which at first glance appear to be contradictory, could be due to the different roles of the NPS system in the brain regions that are important for learning and cognitive flexibility.

Pharmacology, Physiology and Genetics of the Neuropeptide S System

The Neuropeptide S (NPS) system is a rather ‘young’ transmitter system that was discovered and functionally described less than 20 years ago. This review highlights the progress that has been made in elucidating its pharmacology, anatomical distribution, and functional involvement in a variety of physiological effects, including behavior and immune functions. Early on, genetic variations of the human NPS receptor (NPSR1) have attracted attention and we summarize current hypotheses of genetic linkage with disease and human behaviors. Finally, we review the therapeutic potential of future drugs modulating NPS signaling. This review serves as an introduction to the broad collection of original research papers and reviews from experts in the field that are presented in this Special Issue.

Structure-Activity Relationship Studies on Oxazolo[3,4-a]pyrazine Derivatives Leading to the Discovery of a Novel Neuropeptide S Receptor Antagonist with Potent In Vivo Activity

Neuropeptide S modulates important neurobiological functions including locomotion, anxiety, and drug abuse through interaction with its G protein-coupled receptor known as neuropeptide S receptor (NPSR). NPSR antagonists are potentially useful for the treatment of substance abuse disorders against which there is an urgent need for new effective therapeutic approaches. Potent NPSR antagonists in vitro have been discovered which, however, require further optimization of their in vivo pharmacological profile. This work describes a new series of NPSR antagonists of the oxazolo[3,4-a]pyrazine class. The guanidine derivative 16 exhibited nanomolar activity in vitro and 5-fold improved potency in vivo compared to SHA-68, a reference pharmacological tool in this field. Compound 16 can be considered a new tool for research studies on the translational potential of the NPSergic system. An in-depth molecular modeling investigation was also performed to gain new insights into the observed structure-activity relationships and provide an updated model of ligand/NPSR interactions.

Mutant neuropeptide S receptor reduces sleep duration with preserved memory consolidation

Sleep is a crucial physiological process for our survival and cognitive performance, yet the factors controlling human sleep regulation remain poorly understood. Here, we identified a missense mutation in a G protein-coupled neuropeptide S receptor 1 (NPSR1) that is associated with a natural short sleep phenotype in humans. Mice carrying the homologous mutation exhibited less sleep time despite increased sleep pressure. These animals were also resistant to contextual memory deficits associated with sleep deprivation. In vivo, the mutant receptors showed increased sensitivity to neuropeptide S exogenous activation. These results suggest that the NPS/NPSR1 pathway might play a critical role in regulating human sleep duration and in the link between sleep homeostasis and memory consolidation.

Amygdala, neuropeptides, and chronic pain-related affective behaviors

Neuropeptides play important modulatory roles throughout the nervous system, functioning as direct effectors or as interacting partners with other neuropeptide and neurotransmitter systems. Limbic brain areas involved in learning, memory and emotions are particularly rich in neuropeptides. This review will focus on the amygdala, a limbic region that plays a key role in emotional-affective behaviors and pain modulation. The amygdala is comprised of different nuclei; the basolateral (BLA) and central (CeA) nuclei and in between, the intercalated cells (ITC), have been linked to pain-related functions. A wide range of neuropeptides are found in the amygdala, particularly in the CeA, but this review will discuss those neuropeptides that have been explored for their role in pain modulation. Calcitonin gene-related peptide (CGRP) is a key peptide in the afferent nociceptive pathway from the parabrachial area and mediates excitatory drive of CeA neurons. CeA neurons containing corticotropin releasing factor (CRF) and/or somatostatin (SOM) are a source of long-range projections and serve major output functions, but CRF also acts locally to excite neurons in the CeA and BLA. Neuropeptide S (NPS) is associated with inhibitory ITC neurons that gate amygdala output. Oxytocin and vasopressin exert opposite (inhibitory and excitatory, respectively) effects on amygdala output. The opioid system of mu, delta and kappa receptors (MOR, DOR, KOR) and their peptide ligands (β-endorphin, enkephalin, dynorphin) have complex and partially opposing effects on amygdala function. Neuropeptides therefore serve as valuable targets to regulate amygdala function in pain conditions. This article is part of the special issue on Neuropeptides.

Brain neuropeptide S: via GPCR activation to a powerful neuromodulator of socio-emotional behaviors

Neuropeptide S (NPS) has attracted the attention of the scientific community due to its potent anxiolytic-like and fear-attenuating effects studied in rodents. Therefore, NPS might represent a treatment option for neuropsychiatric disorders, such as anxiety disorders, even more so as single nucleotide polymorphisms in the human NPS receptor gene have been associated with increased anxiety traits that contribute to the pathogenesis of fear- and anxiety-related disorders. However, the signaling mechanisms underlying the behavioral effects of NPS and the interaction with other brain neuropeptides are still rather unknown. To illuminate how NPS modulates the expression of selected emotional and social behaviors, the present review focuses on neuroanatomical and electrophysiological studies, as well as intracellular signaling mechanisms following NPS receptor stimulation in rodents. We will also discuss interactions of the NPS system with two well-described neuropeptides, namely corticotropin-releasing factor and oxytocin, which may contribute to the fear- and anxiety-reducing effects.

Peptide welding technology - A simple strategy for generating innovative ligands for G protein coupled receptors

Based on their high selectivity of action and low toxicity, naturally occurring peptides have great potential in terms of drug development. However, the pharmacokinetic properties of peptides, in particular their half life, are poor. Among different strategies developed for reducing susceptibility to peptidases, and thus increasing the duration of action of peptides, the generation of branched peptides has been described. However, the synthesis and purification of branched peptides are extremely complicated thus limiting their druggability. Here we present a novel and facile synthesis of tetrabranched peptides acting as GPCR ligands and their in vitro and vivo pharmacological characterization. Tetrabranched derivatives of nociceptin/orphanin FQ (N/OFQ), N/OFQ related peptides, opioid peptides, tachykinins, and neuropeptide S were generated with the strategy named peptide welding technology (PWT) and characterized by high yield and purity of the desired final product. In general, PWT derivatives displayed a pharmacological profile similar to that of the natural sequence in terms of affinity, pharmacological activity, potency, and selectivity of action in vitro. More importantly, in vivo studies demonstrated that PWT peptides are characterized by increased potency associated with long lasting duration of action. In conclusion, PWT derivatives of biologically active peptides can be viewed as innovative pharmacological tools for investigating those conditions and states in which selective and prolonged receptor stimulation promotes beneficial effects.

Central noradrenergic activity affects analgesic effect of Neuropeptide S

BACKGROUND

Neuropeptide S (NPS) is an endogenous neuropeptide controlling anxiolysis, wakefulness, and analgesia. NPS containing neurons exist near to the locus coeruleus (LC) involved in the descending anti-nociceptive system. NPS interacts with central noradrenergic neurons; thus brain noradrenergic signaling may be involved in NPS-induced analgesia. We tested NPS analgesia in noradrenergic neuron-lesioned rats using a selective LC noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4).

METHODS

A total 66 male Sprague-Dawley rats weighing 350-450 g were used. Analgesic effects of NPS were evaluated using hot-plate and tail-flick test with or without DSP-4. The animal allocated into 3 groups; hot-plate with NPS alone intracerebroventricular (icv) (0.0, 1.0, 3.3, and 10.0 nmol), tail-flick NPS alone icv (0.0 and 10.0 nmol), and hot-plate with NPS and DSP-4 (0 or 50 mg/kg ip). In hot-plate with NPS and DSP-4 group, noradrenaline content in the cerebral cortex, pons, hypothalamus, were measured.

RESULTS

NPS 10 nmol icv prolonged hot plate (%MPE) but not tail flick latency at 30 and 40 min after administration. DSP-4 50 mg/kg decreased noradrenaline content in the all 3 regions. The NA depletion inhibited NPS analgesic effect in the hot plate test but not tail flick test. There was a significant correlation between hot plate latency (percentage of maximum possible effect: %MPE) with NPS 10 nmol and NA content in the cerebral cortex (p = 0.017, r ² = 0.346) which noradrenergic innervation arisen mainly from the LC. No other regions had the correlation.

CONCLUSIONS

NPS analgesia interacts with LC noradrenergic neuronal activity.

Neuropeptide S (NPS) is a neuropeptide with cellular actions in arousal and anxiety-related nuclei: Functional implications for effects of NPS on wakefulness and mood

Neuropeptide S (NPS) is a peptide recently recognized to be present in the CNS, and believed to play a role in vigilance and mood control, as behavioral studies have shown it promotes arousal and has an anxiolytic effect. Although NPS precursor is found in very few neurons, NPS positive fibers are present throughout the brain stem. Given the behavioral actions of this peptide and the wide innervation pattern, we examined the cellular effects of NPS within two brain stem nuclei known to play a critical role in anxiety and arousal: the dorsal raphe (DR) and laterodorsal tegmentum (LDT). In mouse brain slices, NPS increased cytoplasmic levels of calcium in DR and LDT cells. Calcium rises were independent of action potential generation, reduced by low extracellular levels of calcium, attenuated by IP₃ - and ryanodine (RyR)-dependent intracellular calcium store depletion, and eliminated by the receptor (NPSR) selective antagonist, SHA 68. NPS also exerted an effect on the membrane of DR and LDT cells inducing inward and outward currents, which were driven by an increase in conductance, and eliminated by SHA 68. Membrane actions of NPS were found to be dependent on store-mediated calcium as depletion of IP₃ and RyR stores eliminated NPS-induced currents. Finally, NPS also had actions on synaptic events, suggesting facilitation of glutamatergic and GABAergic presynaptic transmission. When taken together, actions of NPS influenced the excitability of DR and LDT neurons, which could play a role in the anxiolytic and arousal-promoting effects of this peptide.

Neuropeptide S precursor knockout mice display memory and arousal deficits

Activation of neuropeptide S (NPS) signaling has been found to produce arousal, wakefulness, anxiolytic-like behaviors, and enhanced memory formation. In order to further study physiological functions of the NPS system, we generated NPS precursor knockout mice by homologous recombination in embryonic stem cells. NPS^-/- mice were viable, fertile, and anatomically normal, when compared to their wild-type and heterozygous littermates. The total number of NPS neurons-although no longer synthesizing the peptide - was not affected by the knockout, as analyzed in NPS^-/- /NPS^EGFP double transgenic mice. Analysis of behavioral phenotypes revealed significant deficits in exploratory activity in NPS^-/- mice. NPS precursor knockout mice displayed attenuated arousal in the hole board test, visible as reduced total nose pokes and number of holes inspected, that was not confounded by increased repetitive or stereotypic behavior. Importantly, long-term memory was significantly impaired in NPS^-/- mice in the inhibitory avoidance paradigm. NPS precursor knockout mice displayed mildly increased anxiety-like behaviors in three different tests measuring responses to stress and novelty. Interestingly, heterozygous littermates often presented behavioral deficits similar to NPS^-/- mice or displayed intermediate phenotype. These observations may suggest limited ligand availability in critical neural circuits. Overall, phenotypical changes in NPS^-/- mice are similar to those observed in NPS receptor knockout mice and support earlier findings that suggest major functions of the NPS system in arousal, regulation of anxiety and stress, and memory formation.

Neuropeptide S receptor ligands: a patent review (2005-2016)

INTRODUCTION

Neuropeptide S (NPS) is a 20-residue peptide and endogenous ligand of the NPS receptor (NPSR). This receptor was a formerly orphan GPCR whose activation increases calcium and cyclic adenosine monophosphate levels. The NPS/NPSR system is expressed in several brain regions where it controls important biological functions including locomotor activity, arousal and sleep, anxiety, food intake, memory, pain, and drug addiction. Areas covered: This review furnishes an updated overview of the patent literature covering NPSR ligands since 2005, when the first example of an NPSR antagonist was disclosed. Expert opinion: Several potent NPSR antagonists are available as valuable pharmacological tools despite showing suboptimal pharmacokinetic properties in vivo. The optimization of these ligands is needed to speed up their potential clinical advancement as pharmaceuticals to treat drug addiction. In order to support the design of novel NPSR antagonists, we performed a ligand-based conformational analysis recognizing some structural requirements for NPSR antagonism. The identification of small-molecule NPSR agonists now represents an unmet challenge to be addressed. These molecules will allow investigation of the beneficial effects of selective NPSR activation in a large panel of psychiatric disorders and to foresee their therapeutic potential as anxiolytics, nootropics, and analgesics.

Selective breeding for high anxiety introduces a synonymous SNP that increases neuropeptide S receptor activity

Neuropeptide S (NPS) has generated substantial interest due to its anxiolytic and fear-attenuating effects in rodents, while a corresponding receptor polymorphism associated with increased NPS receptor (NPSR1) surface expression and efficacy has been implicated in an increased risk of panic disorder in humans. To gain insight into this paradox, we examined the NPS system in rats and mice bred for high anxiety-related behavior (HAB) versus low anxiety-related behavior, and, thereafter, determined the effect of central NPS administration on anxiety- and fear-related behavior. The HAB phenotype was accompanied by lower basal NPS receptor (Npsr1) expression, which we could confirm via in vitro dual luciferase promoter assays. Assessment of shorter Npsr1 promoter constructs containing a sequence mutation that introduces a glucocorticoid receptor transcription factor binding site, confirmed via oligonucleotide pull-down assays, revealed increased HAB promoter activity-an effect that was prevented by dexamethasone. Analogous to the human NPSR1 risk isoform, functional analysis of a synonymous single nucleotide polymorphism in the coding region of HAB rodents revealed that it caused a higher cAMP response to NPS stimulation. Assessment of the behavioral consequence of these differences revealed that intracerebroventricular NPS reversed the hyperanxiety of HAB rodents as well as the impaired cued-fear extinction in HAB rats and the enhanced fear expression in HAB mice, respectively. These results suggest that alterations in the NPS system, conserved across rodents and humans, contribute to innate anxiety and fear, and that HAB rodents are particularly suited to resolve the apparent discrepancy between the preclinical and clinical findings to date.

Neuropeptide S reduces mouse aggressiveness in the resident/intruder test through selective activation of the neuropeptide S receptor

Neuropeptide S (NPS) regulates various biological functions by selectively activating the NPS receptor (NPSR). In particular NPS evokes robust anxiolytic-like effects in rodents together with a stimulant and arousal promoting action. The aim of the study was to investigate the effects of NPS on the aggressiveness of mice subjected to the resident/intruder test. Moreover the putative role played by the endogenous NPS/NPSR system in regulating mice aggressiveness was investigating using mice lacking the NPSR receptor (NPSR(-/-)) and the NPSR selective antagonists [(t)Bu-D-Gly(5)]NPS and SHA 68. NPS (0.01-1 nmol, icv) reduced, in a dose dependent manner, both the time that resident mice spent attacking the intruder mice and their number of attacks, producing pharmacological effects similar to those elicited by the standard anti-aggressive drug valproate (300 mg/kg, ip). This NPS effect was evident in NPSR wild type (NPSR(+/+)) mice but completely disappeared in NPSR(-/-) mice. Moreover, NPSR(-/-) mice displayed a significantly higher time spent attacking than NPSR(+/+) mice. [(t)Bu-D-Gly(5)]NPS (10 nmol, icv) did not change the behavior of mice in the resident/intruder test but completely counteracted NPS effects. SHA 68 (50 mg/kg, ip) was inactive per se and against NPS. In conclusion, this study demonstrated that NPS produces anti-aggressive effects in mice through the selective activation of NPSR and that the endogenous NPS/NPSR system can exert a role in the control of aggressiveness levels under the present experimental conditions.

From neural to genetic substrates of panic disorder: Insights from human and mouse studies

Fear is an ancestral emotion, an intrinsic defensive response present in every organism. Although fear is an evolutionarily advantageous emotion, under certain pathologies such as panic disorder it might become exaggerated and non-adaptive. Clinical and preclinical work pinpoints that changes in cognitive processes, such as perception and interpretation of environmental stimuli that rely on brain regions responsible for high-level function, are essential for the development of fear-related disorders. This review focuses on the involvement of cognitive function to fear circuitry disorders. Moreover, we address how animal models are contributing to understand the involvement of human candidate genes to pathological fear and helping achieve progress in this field. Multidisciplinary approaches that integrate human genetic findings with state of the art genetic mouse models will allow to elucidate the mechanisms underlying pathology and to develop new strategies for therapeutic targeting.

In vitro and in vivo pharmacological characterization of a neuropeptide S tetrabranched derivative

The peptide welding technology (PWT) is a novel chemical strategy that allows the synthesis of multibranched peptides with high yield, purity, and reproducibility. With this approach, a tetrabranched derivative of neuropeptide S (NPS) has been synthesized and pharmacologically characterized. The in vitro activity of PWT1-NPS has been studied in a calcium mobilization assay. In vivo, PWT1-NPS has been investigated in the locomotor activity (LA) and recovery of the righting reflex (RR) tests. In calcium mobilization studies, PWT1-NPS behaved as full agonist at the mouse NPS receptor (NPSR) being threefold more potent than NPS. The selective NPSR antagonists [ (t) Bu-D-Gly(5)]NPS and SHA 68 displayed similar potency values against NPS and PWT1-NPS. In vivo, both NPS (1-100 pmol, i.c.v.) and PWT1-NPS (0.1-100 pmol, i.c.v.) stimulated mouse LA, with PWT1-NPS showing higher potency than NPS. In the RR assay, NPS (100 pmol, i.c.v.) was able to reduce the percentage of mice losing the RR after diazepam administration and their sleep time 5 min after the i.c.v. injection, but it was totally inactive 2 h after the injection. On the contrary, PWT1-NPS (30 pmol, i.c.v.), injected 2 h before diazepam, displayed wake-promoting effects. This PWT1-NPS stimulant effect was no longer evident in mice lacking the NPSR receptor. The PWT1 technology can be successfully applied to the NPS sequence. PWT1-NPS displayed in vitro a pharmacological profile similar to NPS. In vivo PWT1-NPS mimicked NPS effects showing higher potency and long-lasting action.

Amygdala pain mechanisms

A limbic brain area, the amygdala plays a key role in emotional responses and affective states and disorders such as learned fear, anxiety, and depression. The amygdala has also emerged as an important brain center for the emotional-affective dimension of pain and for pain modulation. Hyperactivity in the laterocapsular division of the central nucleus of the amygdala (CeLC, also termed the "nociceptive amygdala") accounts for pain-related emotional responses and anxiety-like behavior. Abnormally enhanced output from the CeLC is the consequence of an imbalance between excitatory and inhibitory mechanisms. Impaired inhibitory control mediated by a cluster of GABAergic interneurons in the intercalated cell masses (ITC) allows the development of glutamate- and neuropeptide-driven synaptic plasticity of excitatory inputs from the brainstem (parabrachial area) and from the lateral-basolateral amygdala network (LA-BLA, site of integration of polymodal sensory information). BLA hyperactivity also generates abnormally enhanced feedforward inhibition of principal cells in the medial prefrontal cortex (mPFC), a limbic cortical area that is strongly interconnected with the amygdala. Pain-related mPFC deactivation results in cognitive deficits and failure to engage cortically driven ITC-mediated inhibitory control of amygdala processing. Impaired cortical control allows the uncontrolled persistence of amygdala pain mechanisms.

Nociceptin/orphanin FQ induces simultaneously anxiolytic and amnesic effects in the mouse elevated T-maze task

Studies have shown a close relationship between anxiety and aversive memory processing, but few animal models are suitable for investigating the effects of a given compound on anxiety and memory simultaneously. A growing body of evidence suggests anxiolytic and amnesic effects of nociceptin/orphanin FQ (N/OFQ). The mouse elevated T-maze (ETM) has been shown to detect the effects of drugs on anxiety and memory at the same time. In this study, the effects of intracerebroventricular N/OFQ injected before or immediately after training session were assessed in the ETM task. When pretraining injected, N/OFQ 0.1 nmol significantly decreased the latency to enter an open arm in the training session compared to control, which is suggestive of anxiolysis. In addition, N/OFQ (0.1 and 1 nmol) significantly reduced the latency to enter an open arm during the test session compared to control, thus suggesting memory impairments. However, when N/OFQ was administered posttraining, it did not affect memory retrieval. No alterations in locomotion were detected in N/OFQ-treated mice in the open field test. In conclusion, these findings are discussed considering the simultaneous anxiolytic and amnesic effects of N/OFQ.

Central adenosine A1 and A2A receptors mediate the antinociceptive effects of neuropeptide S in the mouse formalin test

AIMS

The present study aimed to investigate the intraplantar (ipl) and central (icv) effects of neuropeptide S (NPS) in the formalin test and to evaluate the role of adenosine receptors, mainly A1 and A2A, in mediating such effects.

MAIN METHODS

The ipl injection of formalin was used to assess the nociceptive activity. Moreover, by pretreating mice with non-selective and selective antagonists of adenosine receptors, the effects of icv NPS on formalin-induced ongoing nociception were assessed.

KEY FINDINGS

Morphine-induced antinociceptive effects were observed during phases 1 and 2 of the test, while indomethacin was active only at the later nociceptive phase. The ipl injection of NPS (alone or combined with formalin) did not modify the nociceptive response. However, icv NPS significantly reduced formalin-induced nociception during both phases. Caffeine (3 mg/kg, ip), a non-selective adenosine receptor antagonist, prevented NPS-induced antinociceptive effects. Similar to caffeine, icv ZM241385 (0.01 nmol), an A2A receptor antagonist, prevented the antinociceptive effects of NPS. Moreover, icv DPCPX (0.001 nmol), an A1 receptor antagonist, blocked the effects of NPS only during phase 1.

SIGNIFICANCE

The above findings suggest that: (i) NPS evokes central antinociceptive effects by activating both A1 and A2A receptors during phase 1, but (ii) only the adenosine A2A receptor during phase 2 of the formalin test.

Paradoxical response to the sedative effects of diazepam and alcohol in C57BL/6J mice lacking the neuropeptide S receptor

The neuropeptide S (NPS) system is characterized by a unique pharmacology because it has anxiolytic-like effects and promotes arousal and wakefulness. To shed light on this peptidergic system, we tested the sedative effect of the central depressants diazepam and ethanol on the loss of righting reflex in mice lacking the neuropeptide S receptor (NPSR), NPSR(-/-). Furthermore, we tested the effect of the intracerebroventricular (ICV) administration of NPS on the sedative effect of diazepam and ethanol in NPSR(-/-) and their wild type counterpart NPSR(+/+). Finally, we evaluated the effect of the pro-arousal neuropeptides CRF and Hcrt-1/Ox-A in NPSR-deficient mice. Contrary to our expectations, the results showed that the NPSR(-/-) were less sensitive to the hypnotic effects of both diazepam and ethanol compared with their wild type littermates. ICV NPS was able to attenuate the sedative effect of both alcohol and diazepam in wild type mice, but not in the NPSR(-/-) line. The administration of CRF and Hcrt-1/Ox-A, two classic pro-arousal peptides, elicited the same effects in both NPSR(-/-) and wild type mice, ruling out the possibility that adaptive mechanisms occurring at the level of these two systems could have occurred during NPSR(-/-) development to compensate for the lack of NPSR receptors. Our findings demonstrated that the deletion of NPSR leads to minor changes in the arousal behavior of mice. Moreover, we demonstrated that the deletion of NPSR did not lead to compensatory changes in the vigilance-promoting effects of the CRF and Hcrt-1/Ox-A systems.

Endogenous neuropeptide S tone influences sleep-wake rhythm in rats

Neuropeptide S (NPS) is an endogenous peptide that exerts wakefulness promoting, analgesic, and anxiolytic effects when administered exogenously. However, it remains to be determined if endogenous NPS tone is involved in the control of the diurnal sleep-wake cycle, or spontanous behavior. In this study, we examined the effects of the NPS receptor antagonist [D-Cys((t)Bu)(5)]NPS (2 and 20 nmol, icv) on physiological sleep and spontaneous locomotor behavior. The higher dose of [D-Cys((t)Bu)(5)]NPS decreased the amount of time spent in wakefulness [control 782.5 ± 25.5 min, treatment 751.7 ± 28.1 min; p<0.05] and increased the time spent in NREMS [control 572.6 ± 17.2 min, treatment 600.2 ± 26.1 min; p<0.05]. There was no statistically significant difference in time spent in REMS. There were no behavioral changes including abnormal gross motor behavior in response to [D-Cys((t)Bu)(5)]NPS administration. Collectively these data suggest an involvement of the endogenous NPS/NPS receptor system in physiological sleep architecture.

Nasal application of neuropeptide S inhibits arthritis pain-related behaviors through an action in the amygdala

Recently discovered neuropeptide S (NPS) has anxiolytic and pain-inhibiting effects in rodents. We showed previously that NPS increases synaptic inhibition of amygdala output to inhibit pain behaviors. The amygdala plays a key role in emotional-affective aspects of pain. Of clinical significance is that NPS can be applied nasally to exert anxiolytic effects in rodents. This study tested the novel hypothesis that nasal application of NPS can inhibit pain-related behaviors in an arthritis model through NPS receptors (NPSR) in the amygdala. Behaviors and electrophysiological activity of amygdala neurons were measured in adult male Sprague Dawley rats. Nasal application of NPS, but not saline, inhibited audible and ultrasonic vocalizations and had anxiolytic-like effects in the elevated plus-maze test in arthritic rats (kaolin/carrageenan knee joint arthritis model) but had no effect in normal rats. Stereotaxic application of a selective non-peptide NPSR antagonist (SHA68) into the amygdala by microdialysis reversed the inhibitory effects of NPS. NPS had no effect on hindlimb withdrawal thresholds. We showed previously that intra-amygdala application of an NPSR antagonist alone had no effect. Nasal application of NPS or stereotaxic application of NPS into the amygdala by microdialysis inhibited background and evoked activity of amygdala neurons in arthritic, but not normal, anesthetized rats. The inhibitory effect was blocked by a selective NPSR antagonist ([D-Cys(tBu)5]NPS). In conclusion, nasal application of NPS can inhibit emotional-affective, but not sensory, pain-related behaviors through an action in the amygdala. The beneficial effects of non-invasive NPS application may suggest translational potential.

Persistent nociception induces anxiety-like behavior in rodents: role of endogenous neuropeptide S

Anxiety disorder is a comorbid condition of chronic pain. Analgesics and anxiolytics, subject to addiction and abuse, are currently used to manage pain and anxiety symptoms. However, the cellular mechanism underlying chronic pain and anxiety interaction remains to be elucidated. We report that persistent nociception following peripheral nerve injury induced anxiety-like behavior in rodents. Brain expression and release of neuropeptide S (NPS), a proposed endogenous anxiolytic peptide, was diminished in rodents with coexisting nociceptive and anxiety-like behaviors. Intracerebroventricular administration of exogenous NPS concurrently improved both nociceptive and anxiety-like behaviors. At the cellular level, NPS enhanced intra-amygdaloidal inhibitory transmission by increasing presynaptic gamma-aminobutyric acid (GABA) release from interneurons. These findings indicate that the interaction between nociceptive and anxiety-like behaviors in rodents may be regulated by the altered NPS-mediated intra-amygdaloidal GABAergic inhibition. The data suggest that enhancing the brain NPS function may be a new strategy to manage comorbid pain and anxiety.

Neuropeptide S and BDNF gene expression in the amygdala are influenced by social decision-making under stress

In a newly developed conceptual model of stressful social decision-making, the Stress-Alternatives Model (SAM; used for the 1st time in mice) elicits two types of response: escape or remain submissively. Daily (4d) aggressive social interaction in a neutral arena between a C57BL6/N test mouse and a larger, novel aggressive CD1 mouse, begin after an audible tone (conditioned stimulus; CS). Although escape holes (only large enough for smaller test animals) are available, and the aggressor is unremittingly antagonistic, only half of the mice tested utilize the possibility of escape. During training, for mice that choose to leave the arena and social interaction, latency to escape dramatically decreases over time; this is also true for control C57BL6/N mice which experienced no aggression. Therefore, the open field of the SAM apparatus is intrinsically anxiogenic. It also means that submission to the aggressor is chosen despite this anxiety and the high intensity of the aggressive attacks and defeat. While both groups that received aggression displayed stress responsiveness, corticosterone levels were significantly higher in animals that chose submissive coexistence. Although both escaping and non-escaping groups of animals experienced aggression and defeat, submissive animals also exhibited classic fear conditioning, freezing in response to the CS alone, while escaping animals did not. In the basolateral amygdala (BLA), gene expression of brain-derived neurotrophic factor (BDNF) was diminished, at the same time neuropeptide S (NPS) expression was significantly elevated, but only in submissive animals. This increase in submission-evoked NPS mRNA expression was greatest in the central amygdala (CeA), which coincided with decreased BDNF expression. Reduced expression of BDNF was only found in submissive animals that also exhibit elevated NPS expression, despite elevated corticosterone in all socially interacting animals. The results suggest an interwoven relationship, linked by social context, between amygdalar BDNF, NPS and plasma corticosterone.

Role of neuropeptides in anxiety, stress, and depression: from animals to humans

Major depression, with its strikingly high prevalence, is the most common cause of disability in communities of Western type, according to data of the World Health Organization. Stress-related mood disorders, besides their deleterious effects on the patient itself, also challenge the healthcare systems with their great social and economic impact. Our knowledge on the neurobiology of these conditions is less than sufficient as exemplified by the high proportion of patients who do not respond to currently available medications targeting monoaminergic systems. The search for new therapeutical strategies became therefore a "hot topic" in neuroscience, and there is a large body of evidence suggesting that brain neuropeptides not only participate is stress physiology, but they may also have clinical relevance. Based on data obtained in animal studies, neuropeptides and their receptors might be targeted by new candidate neuropharmacons with the hope that they will become important and effective tools in the management of stress related mood disorders. In this review, we attempt to summarize the latest evidence obtained using animal models for mood disorders, genetically modified rodent models for anxiety and depression, and we will pay some attention to previously published clinical data on corticotropin releasing factor, urocortin 1, urocortin 2, urocortin 3, arginine-vasopressin, neuropeptide Y, pituitary adenylate-cyclase activating polypeptide, neuropeptide S, oxytocin, substance P and galanin fields of stress research.

In vitro and in vivo pharmacological characterization of the novel neuropeptide S receptor ligands QA1 and PI1

The pharmacological activity of the novel neuropeptide S (NPS) receptor (NPSR) ligands QA1 and PI1 was investigated. In vitro QA1 and PI1 were tested in calcium mobilization studies performed in HEK293 cells expressing the recombinant mouse (HEK293mNPSR) and human (HEK293hNPSRIle107 and HEK293hNPSRAsn107) NPSR receptors. In vivo the compounds were studied in mouse righting reflex (RR) and locomotor activity (LA) tests. NPS caused a concentration dependent mobilization of intracellular calcium in the three cell lines with high potency (pEC50 8.73-9.14). In inhibition response curve and Schild protocol experiments the effects of NPS were antagonized by QA1 and PI1. QA1 displayed high potency (pKB 9.60-9.82) behaving as a insurmountable antagonist. However in coinjection experiments QA1 produced a rightward swift of the concentration response curve to NPS without modifying its maximal effects; this suggests that QA1 is actually a slow dissociating competitive antagonist. PI1 displayed a competitive type of antagonism and lower values of potencies (pA2 7.74-8.45). In vivo in mice NPS (0.1 nmol, i.c.v.) elicited arousal promoting action in the RR assay and stimulant effects in the LA test. QA1 (30 mgkg(-1)) was able to partially counteract the arousal promoting NPS effects, while PI1 was inactive in the RR test. In the LA test QA1 and PI1 only poorly blocked the NPS stimulant action. The present data demonstrated that QA1 and PI1 act as potent NPSR antagonists in vitro, however their usefulness for in vivo investigations in mice seems limited probably by pharmacokinetic reasons.

Neuropeptide S: a novel regulator of pain-related amygdala plasticity and behaviors

Amygdala plasticity is an important contributor to the emotional-affective dimension of pain. Recently discovered neuropeptide S (NPS) has anxiolytic properties through actions in the amygdala. Behavioral data also suggest antinociceptive effects of centrally acting NPS, but site and mechanism of action remain to be determined. This is the first electrophysiological analysis of pain-related NPS effects in the brain. We combined whole cell patch-clamp recordings in brain slices and behavioral assays to test the hypothesis that NPS activates synaptic inhibition of amygdala output to suppress pain behavior in an arthritis pain model. Recordings of neurons in the laterocapsular division of the central nucleus (CeLC), which serves pain-related amygdala output functions, show that NPS inhibited the enhanced excitatory drive [monosynaptic excitatory postsynaptic currents (EPSCs)] from the basolateral amygdala (BLA) in the pain state. As shown by miniature EPSC analysis, the inhibitory effect of NPS did not involve direct postsynaptic action on CeLC neurons but rather a presynaptic, action potential-dependent network mechanism. Indeed, NPS increased external capsule (EC)-driven synaptic inhibition of CeLC neurons through PKA-dependent facilitatory postsynaptic action on a cluster of inhibitory intercalated (ITC) cells. NPS had no effect on BLA neurons. High-frequency stimulation (HFS) of excitatory EC inputs to ITC cells also inhibited synaptic activation of CeLC neurons, providing further evidence that ITC activation can control amygdala output. The cellular mechanisms by which EC-driven synaptic inhibition controls CeLC output remain to be determined. Administration of NPS into ITC, but not CeLC, also inhibited vocalizations and anxiety-like behavior in arthritic rats. A selective NPS receptor antagonist ([d-Cys(tBu)(5)]NPS) blocked electrophysiological and behavioral effects of NPS. Thus NPS is a novel tool to control amygdala output and pain-related affective behaviors through a direct action on inhibitory ITC cells.

Neuropeptide S enhances memory and mitigates memory impairment induced by MK801, scopolamine or Aβ₁₋₄₂ in mice novel object and object location recognition tasks

Neuropeptide S (NPS), the endogenous ligand of NPSR, has been shown to promote arousal and anxiolytic-like effects. According to the predominant distribution of NPSR in brain tissues associated with learning and memory, NPS has been reported to modulate cognitive function in rodents. Here, we investigated the role of NPS in memory formation, and determined whether NPS could mitigate memory impairment induced by selective N-methyl-D-aspartate receptor antagonist MK801, muscarinic cholinergic receptor antagonist scopolamine or Aβ₁₋₄₂ in mice, using novel object and object location recognition tasks. Intracerebroventricular (i.c.v.) injection of 1 nmol NPS 5 min after training not only facilitated object recognition memory formation, but also prolonged memory retention in both tasks. The improvement of object recognition memory induced by NPS could be blocked by the selective NPSR antagonist SHA 68, indicating pharmacological specificity. Then, we found that i.c.v. injection of NPS reversed memory disruption induced by MK801, scopolamine or Aβ₁₋₄₂ in both tasks. In summary, our results indicate that NPS facilitates memory formation and prolongs the retention of memory through activation of the NPSR, and mitigates amnesia induced by blockage of glutamatergic or cholinergic system or by Aβ₁₋₄₂, suggesting that NPS/NPSR system may be a new target for enhancing memory and treating amnesia.

The role of the neuropeptide S system in addiction: focus on its interaction with the CRF and hypocretin/orexin neurotransmission

Recent behavioral, pharmacological and molecular findings have linked the NPS system to drug dependence. Most of the evidence supports the possibility that increased NPS activity may contribute to shaping vulnerability to addiction, especially relapse. However, data suggesting that the anxiolytic-like properties of NPS may have protective effects on addiction have been also published. In addition, evidence from conditioned place preference experiments, though not unequivocal, suggests that NPS per se is devoid of motivational properties. Intriguingly, several effects of NPS on drugs of abuse appear to be mediated by downstream activation of brain corticotrophin releasing factor (CRF) and hypocretin-1/orexin-A (Hcrt-1/Ox-A) systems. The major objective of the present article is to review the existing work on NPS and addiction. Particular attention is devoted to the interpretation of findings revealing complex neuroanatomical and functional interactions between NPS, CRF, and the Hcrt-1/Ox-A systems. Original data aimed at shedding light on the role of NPS in reward processing are also shown. Finally, existing findings are discussed within the framework of addiction theories, and the potential of the NPS system as a treatment target for addiction is analyzed.

Anxiolytic- and panicolytic-like effects of Neuropeptide S in the mouse elevated T-maze

Neuropeptide S (NPS) regulates various biological functions by selectively activating the NPS receptor (NPSR). Recently, epidemiological studies revealed an association between NPSR single nucleotide polymorphisms and susceptibility to panic disorders. Here we investigated the effects of NPS in mice subjected to the elevated T maze (ETM), an assay which has been proposed to model anxiety and panic. Diazepam [1 mg/kg, intraperitoneally (i.p.)] elicited clear anxiolytic effects reducing the latency to emerge from the closed to the open (CO) arm without modifying the latencies from the open to the closed (OC) arm. By contrast, chronic fluoxetine (10 mg/kg i.p., once a day for 21 days) selectively increased OC latency, suggesting a panicolytic-like effect. NPS given intracerebroventricularly at 0.001-1 nmol elicited both anxiolytic- and panicolytic-like effects. However, although the NPS anxiolytic dose-response curve displayed the classical sigmoidal shape, the dose-response curve of the putative panicolytic-like effect was bell shaped with peak effect at 0.01 nmol. The behaviour of wild-type [NPSR(+/+)] and receptor knock out [NPSR(-/-)] mice in the ETM task was superimposable. NPS at 0.01 nmol elicited anxiolytic- and panicolytic-like effects in NPSR(+/+) but not in NPSR(-/-) mice. In conclusion, this study demonstrated that NPS, via selective activation of the NPSR, promotes both anxiolytic- and panicolytic-like actions in the mouse ETM.