Neuropeptide S: a neuropeptide promoting arousal and anxiolytic-like effects

Role of the neuropeptide S receptor 1 rs324981 polymorphism in modulating emotionality and cognitive flexibility: Insights from a gene-edited mouse model

The neuropeptide S (NPS) and its receptor (NPSR1) are involved in various physiological processes, including arousal, sleep, anxiety, memory, and stress responses in rodents. Recent attention has focused on the association between the NPS/NPSR1 system and stress-related disorders, particularly involving a specific single nucleotide polymorphism (SNP) in the NPSR1 gene (rs324981). This SNP causes an amino acid change at position 107 in the protein, reducing NPSR1 signalling potency; however, its effects on behavioural, cognitive, and physiological aspects relevant to stress-related disorders remain unclear. Addressing this topic, we characterized the behavioural phenotype of a gene-editing mouse model, expressing either the murine/ancestral NPSR1-I107 variant or the human NPSR1-N107 variant. Both, male and female mice underwent a comprehensive behavioural test battery assessing arousal, exploratory and anxiety-related behaviour under varying levels of novelty stress. Moreover, cognitive functions were evaluated with a special focus on cognitive flexibility using the Attentional Set Shifting Task (ASST). Additionally, markers of behavioural and endocrine stress reactivity were assessed as well as changes in body weight and body composition. Our results showed that NPSR1-N107 mice displayed increased anxiety-related behaviour compared to NPSR1-I107 mice, with no significant differences in arousal, exploratory behaviour or hormonal stress responses. However, NPSR1-N107 mice also exhibited better rule-reversal learning in the ASST, indicating enhanced cognitive flexibility. These findings provide clear evidence for a role of the NPSR1 rs324981 SNP in regulating emotionality and cognitive flexibility, underscoring the potential of the NPSR1-I107N mouse model for further elucidating the molecular mechanisms underlying stress-related disorders.

Pupil size reveals arousal level fluctuations in human sleep

Recent animal research has revealed the intricate dynamics of arousal levels that are important for maintaining proper sleep resilience and memory consolidation. In humans, changes in arousal level are believed to be a determining characteristic of healthy and pathological sleep but tracking arousal level fluctuations has been methodologically challenging. Here we measured pupil size, an established indicator of arousal levels, by safely taping the right eye open during overnight sleep and tested whether pupil size affects cortical response to auditory stimulation. We show that pupil size dynamics change as a function of important sleep events across different temporal scales. In particular, our results show pupil size to be inversely related to the occurrence of sleep spindle clusters, a marker of sleep resilience. Additionally, we found pupil size prior to auditory stimulation to influence the evoked response, most notably in delta power, a marker of several restorative and regenerative functions of sleep. Recording pupil size dynamics provides insights into the interplay between arousal levels and sleep oscillations.

Mesenchymal stem cells overexpressing neuropeptide S promote the recovery of rats with spinal cord injury by activating the PI3K/AKT/GSK3β signaling pathway

BACKGROUND

Transplantation of nasal mucosa-derived mesenchymal stem cells (EMSCs) overexpressing neuropeptide S (NPS) is a promising approach for treating spinal cord injury (SCI). Despite the potential of stem cell therapy, challenges remain regarding cell survival and differentiation control. We aimed to conduct orthotopic transplantation of transected spinal cord to treat rats with complete SCI.

METHODS

In this study, we loaded NPS-overexpressing EMSCs onto hydrogels to enhance cell survival in vivo and promote neuronal differentiation both in vitro and in vivo. However, in vitro co-culture promoted greater neuronal differentiation of neural stem cells (P < 0.01). When transplanted in vivo, NPS-overexpressing EMSCs showed greater cell survival in the transplanted area compared with stem cells without gene modification within 4 weeks after spinal cord implantation in rats (P < 0.01).

RESULTS

Compared with those in the other groups, stable overexpression of NPS-EMSCs in a rat model with SCI significantly improved the treatment effect, reduced glial scar formation, promoted neural regeneration and endogenous neural stem cell proliferation and differentiation into neurons, and improved motor function.

CONCLUSIONS

These results indicate that this effect may be achieved by the overexpression of NPS-EMSCs through the activation of the PI3K/Akt/GSK3β signaling pathway. Overall, the overexpression of EMSCs significantly improved the therapeutic effect of SCI in rats, strongly supporting the potential for gene modification of mesenchymal stem cells in clinical applications.

Arousal-promoting effect of the parabrachial nucleus and the underlying mechanisms: Recent advances

The parabrachial nucleus (PBN) is responsible for integrating both internal and external sensory information and controlling/regulating a wide range of physiological processes, such as feeding, thermogenesis, nociceptive and pruritic sensations, and respiration. Recently, the PBN has been found to be involved in mediating wakefulness maintenance, sleep-wake transition, exogenous neuromodulation of awakening, and arousal-promoting process triggered by drastic changes in the internal environments, such as hypercapnia, hypoxia, and hypertension. Multiple neural pathways and subpopulations of neurons are responsible for arousal-promoting effects of the PBN. The medial PBN seems to be more important for the maintenance of physiological arousal, while the lateral PBN are more crucial in mediating interoception-driven arousal. Glutamatergic projection from the PBN to the basal forebrain (BF) and GABAergic projection from the BF to the cerebral cortex GABAergic neurons are the most pivotal neural pathways for awareness-promotion. Here, we review the relevant literature in this field in recent years and emphasize the potential prospects of PBN stimulation in translational medicine for the rehabilitation of disorders of consciousness.

Central treatment of neuropeptide-S attenuates cognitive dysfunction and hippocampal synaptic plasticity impairment by increasing CaMKII/GluR1 in hemiparkinsonian rats

Neuropeptide-S (NPS) has been demonstrated to mitigate learning and memory deficits in experimental models of Parkinson's Disease (PD). Despite this, the precise mechanisms through which NPS exerts its influence on cognitive functions remain to be fully unknown. This study aims to elucidate the effects of central administration of NPS on learning and memory deficits associated with an experimental rat hemiparkinsonian model, examining both electrophysiological and molecular parameters. The hemiparkinsonian model was established via stereotactic injection of 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle. Central NPS (1 nmol, icv) was administered into the lateral ventricle via a cannula for seven consecutive days following the 6-OHDA lesion. The Morris water maze and object recognition tests were used to evaluate the rat's learning and memory abilities. Long-term potentiation (LTP) recordings were conducted to assess hippocampal synaptic plasticity. Immunohistochemistry was employed to determine the expression levels of phosphorylated CaMKII (pCaMKII), GluR1, and GluR2 in the hippocampus. The 6-OHDA-induced decline in cognitive performance was significantly (p < 0.05) improved in rats that received central NPS. In 6-OHDA-lesioned rats, NPS treatment significantly (p < 0.05) enhanced the amplitude of LTP at the dentate gyrus/perforant path synapses. Furthermore, NPS significantly (p < 0.05) increased the number of pCaMKII and GluR1 immunoreactive cells in the hippocampus, which had been diminished due to 6-OHDA, except for GluR2 levels. These findings provide insight into the mechanisms by which central NPS administration enhances cognitive functions in an experimental model of PD, highlighting its potential therapeutic benefits for addressing cognitive deficits in PD.

Heritability and Genome-Wide Association Study of Dog Behavioral Phenotypes in a Commercial Breeding Cohort

Background: Canine behavior plays an important role in the success of the human-dog relationship and the dog's overall welfare, making selection for behavior a vital part of any breeding program. While behaviors are complex traits determined by gene × environment interactions, genetic selection for desirable behavioral phenotypes remains possible. Methods: No genomic association studies of dog behavior to date have been reported on a commercial breeding (CB) cohort; therefore, we utilized dogs from these facilities (n = 615 dogs). Behavioral testing followed previously validated protocols, resulting in three phenotypes/variables [social fear (SF), non-social fear (NSF), and startle response (SR)]. Dogs were genotyped on the 710 K Affymetrix Axiom CanineHD SNP array. Results: Inbreeding coefficients indicated that dogs from CB facilities are statistically less inbred than dogs originating from other breeding sources. Heritability estimates for behavioral phenotypes ranged from 0.042 ± 0.045 to 0.354 ± 0.111. A genome-wide association analysis identified genetic loci associated with SF, NSF, and SR; genes near many of these loci have been previously associated with behavioral phenotypes in other populations of dogs. Finally, genetic risk scores demonstrated differences between dogs that were more or less fearful in response to test stimuli, suggesting that these behaviors could be subjected to genetic improvement. Conclusions: This study confirms several canine genetic behavioral loci identified in previous studies. It also demonstrates that inbreeding coefficients of dogs in CB facilities are typically lower than those in dogs originating from other breeding sources. SF and NSF were more heritable than SR. Risk allele and weighted risk scores suggest that fearful behaviors could be subjected to genetic improvement.

Emerging pharmacological targets for alcohol use disorder

Alcohol Use Disorder (AUD) remains a challenging condition with limited effective treatment options; however new technology in drug delivery and advancements in pharmacology have paved the way for discovery of novel therapeutic targets. This review explores emerging pharmacological targets that offer new options for the management of AUD, focusing on the potential of somatostatin (SST), vasoactive intestinal peptide (VIP), glucagon-like peptide-1 (GLP-1), nociceptin (NOP), and neuropeptide S (NPS). These targets have been selected based on recent advancements in preclinical and clinical research, which suggest their significant roles in modulating alcohol consumption and related behaviors. SST dampens cortical circuits, and targeting both the SST neurons and the SST peptide itself presents promise for treating AUD and various related comorbidities. VIP neurons are modulated by alcohol and targeting the VIP system presents an unexplored avenue for addressing alcohol exposure at various stages of development. GLP-1 interacts with the dopaminergic reward system and reduces alcohol intake. Nociceptin modulates mesolimbic circuitry and agonism and antagonism of nociceptin receptor offers a complex but promising approach to reducing alcohol consumption. NPS stands out for its anxiolytic-like effects, particularly relevant for the anxiety associated with AUD. This review aims to synthesize the current understanding of these targets, highlighting their potential in developing more effective and personalized AUD therapies, and underscores the importance of continued research in identifying and validating novel targets for treatment of AUD and comorbid conditions.

The Influence of the Estrous Cycle on Neuropeptide S Receptor-Mediated Behaviors

The neuropeptide S receptor (NPSR) has been identified as a potential therapeutic target for anxiety and post-traumatic stress disorder. Central administration of neuropeptide S (NPS) in male mice produces anxiolytic-like effects, hyperlocomotion, and memory enhancement. Currently, the literature is limited in the number of studies investigating the effects of NPS in female test subjects despite females facing a higher prevalence of anxiety-related pathology, as well as greater risk for adverse effects while taking psychoactive drugs. Moreover, no previous studies have considered the influence of estrous cycle on the effects of NPS. The present study investigates whether NPS-mediated behavioral phenotypes seen in males translate to females, and whether they are affected by estrous cycle stage. Female C57BL/6NCr mice were intracerebroventricularly cannulated and underwent behavioral paradigms to test locomotion, anxiety, and memory. Estrous cycle stage was determined through examination of vaginal cytology. Our results provide evidence that NPS-mediated behaviors are influenced by the estrous cycle. Administration of NPS decreased anxiety-like behaviors more robustly when the female mice were in high estrogen stages of the estrous cycle. Therefore, the desired anxiolytic-like effects of targeting the NPSR are intact in female mice. However, these effects may to be influenced by the stage of the estrous cycle. The NPSR remains a strong potential drug target for new anxiolytic compounds and based on our initial observations further studies exploring the interaction of estrous cycle and the NPS system are warranted. SIGNIFICANCE STATEMENT: The neuropeptide S (NPS) receptor has been identified as a potential target for treating anxiety, a condition that is most prevalent in females. Therefore, the potential interaction of estrous cycle with the NPS system described in the present study is an important first step in understanding the function of the NPS system in females.

RNA m6A methyltransferase activator affects anxiety-related behaviours, monoamines and striatal gene expression in the rat

Modification of mRNA by methylation is involved in post-transcriptional regulation of gene expression by affecting the splicing, transport, stability and translation of mRNA. Methylation of adenosine at N6 (m6A) is one of the most common and important cellular modification occurring in the mRNA of eukaryotes. Evidence that m6A mRNA methylation is involved in regulation of stress response and that its dysregulation may contribute to the pathogenesis of neuropsychiatric disorders is accumulating. We have examined the acute and subchronic (up to 18 days once per day intraperitoneally) effect of the first METTL3/METTL14 activator compound CHMA1004 (methyl-piperazine-2-carboxylate) at two doses (1 and 5 mg/kg) in male and female rats. CHMA1004 had a locomotor activating and anxiolytic-like profile in open field and elevated zero-maze tests. In female rats sucrose consumption and swimming in Porsolt's test were increased. Nevertheless, CHMA1004 did not exhibit strong psychostimulant-like properties: CHMA1004 had no effect on 50-kHz ultrasonic vocalizations except that it reduced the baseline difference between male and female animals, and acute drug treatment had no effect on extracellular dopamine levels in striatum. Subchronic CHMA1004 altered ex vivo catecholamine levels in several brain regions. RNA sequencing of female rat striata after subchronic CHMA1004 treatment revealed changes in the expression of a number of genes linked to dopamine neuron viability, neurodegeneration, depression, anxiety and stress response. Conclusively, the first-in-class METTL3/METTL14 activator compound CHMA1004 increased locomotor activity and elicited anxiolytic-like effects after systemic administration, demonstrating that pharmacological activation of RNA m6A methylation has potential for neuropsychiatric drug development.

Western diet-induced cognitive and metabolic dysfunctions in aged mice are prevented by rosmarinic acid in a sex-dependent fashion

BACKGROUND & AIMS

Unhealthy lifestyles, such as chronic consumption of a Western Diet (WD), have been associated with increased systemic inflammation and oxidative stress (OS), a condition that may favour cognitive dysfunctions during aging. Polyphenols, such as rosmarinic acid (RA) may buffer low-grade inflammation and OS, characterizing the aging brain that is sustained by WD, promoting healthspan. The aim of this study was to evaluate the ability of RA to prevent cognitive decline in a mouse model of WD-driven unhealthy aging and to gain knowledge on the specific molecular pathways modulated within the brain.

METHODS

Aged male and female C57Bl/6N mice were supplemented either with RA or vehicle for 6 weeks. Following 2 weeks on RA they started being administered either with WD or control diet (CD). Successively all mice were tested for cognitive abilities in the Morris water maze (MWM) and emotionality in the elevated plus maze (EPM). Glucose and lipid homeostasis were assessed in trunk blood while the hippocampus was dissected out for RNAseq transcriptomic analysis.

RESULTS

RA prevented insulin resistance in males while protecting both males and females from WD-dependent memory impairment. In the hippocampus, RA modulated OS pathways in males and immune- and sex hormones-related signalling cascades (Lhb and Lhcgr genes) in females. Moreover, RA overall resulted in an upregulation of Glp1r, recently identified as a promising target to prevent metabolic derangements. In addition, we also found an RA-dependent enrichment in nuclear transcription factors, such as NF-κB, GR and STAT3, that have been recently suggested to promote healthspan and longevity by modulating inflammatory and cell survival pathways.

CONCLUSIONS

Oral RA supplementation may promote brain and metabolic plasticity during aging through antioxidant and immune-modulating properties possibly affecting the post-reproductive hormonal milieu in a sex-dependent fashion. Thus, its supplementation should be considered in the context of precision medicine as a possible strategy to preserve cognitive functions and to counteract metabolic derangements.

Impact of NPSR1 gene variation on the neural correlates of phasic and sustained fear in spider phobia-an imaging genetics and independent replication approach

The functional neuropeptide S receptor 1 (NPSR1) gene A/T variant (rs324981) is associated with fear processing. We investigated the impact of NPSR1 genotype on fear processing and on symptom reduction following treatment in individuals with spider phobia. A replication approach was applied [discovery sample: Münster (MS) nMS = 104; replication sample Würzburg (WZ) nWZ = 81]. Participants were genotyped for NPSR1 rs324981 [T-allele carriers (risk) versus AA homozygotes (no-risk)]. A sustained and phasic fear paradigm was applied during functional magnetic resonance imaging. A one-session virtual reality exposure treatment was conducted. Change of symptom severity from pre to post treatment and within session fear reduction were assessed. T-allele carriers in the discovery sample displayed lower anterior cingulate cortex (ACC) activation compared to AA homozygotes independent of condition. For sustained fear, this effect was replicated within a small cluster and medium effect size. No association with symptom reduction was found. Within-session fear reduction was negatively associated with ACC activation in T-allele carriers in the discovery sample. NPSR1 rs324981 genotype might be associated with fear processing in the ACC in spider phobia. Interpretation as potential risk-increasing function of the NPSR1 rs324981 T-allele via impaired top-down control of limbic structures remains speculative. Potential association with symptom reduction warrants further research.

Alterations of pleiotropic neuropeptide-receptor gene couples in Cetacea

BACKGROUND

Habitat transitions have considerable consequences in organism homeostasis, as they require the adjustment of several concurrent physiological compartments to maintain stability and adapt to a changing environment. Within the range of molecules with a crucial role in the regulation of different physiological processes, neuropeptides are key agents. Here, we examined the coding status of several neuropeptides and their receptors with pleiotropic activity in Cetacea.

RESULTS

Analysis of 202 mammalian genomes, including 41 species of Cetacea, exposed an intricate mutational landscape compatible with gene sequence modification and loss. Specifically for Cetacea, in the 12 genes analysed we have determined patterns of loss ranging from species-specific disruptive mutations (e.g. neuropeptide FF-amide peptide precursor; NPFF) to complete erosion of the gene across the cetacean stem lineage (e.g. somatostatin receptor 4; SSTR4).

CONCLUSIONS

Impairment of some of these neuromodulators may have contributed to the unique energetic metabolism, circadian rhythmicity and diving response displayed by this group of iconic mammals.

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.

A cluster of neuropeptide S neurons regulates breathing and arousal

Neuropeptide S (NPS) is a highly conserved peptide found in all tetrapods that functions in the brain to promote heightened arousal; however, the subpopulations mediating these phenomena remain unknown. We generated mice expressing Cre recombinase from the Nps gene locus (NpsCre) and examined populations of NPS+ neurons in the lateral parabrachial area (LPBA), the peri-locus coeruleus (peri-LC) region of the pons, and the dorsomedial thalamus (DMT). We performed brain-wide mapping of input and output regions of NPS+ clusters and characterized expression patterns of the NPS receptor 1 (NPSR1). While the activity of all three NPS+ subpopulations tracked with vigilance state, only NPS+ neurons of the LPBA exhibited both increased activity prior to wakefulness and decreased activity during REM sleep, similar to the behavioral phenotype observed upon NPSR1 activation. Accordingly, we found that activation of the LPBA but not the peri-LC NPS+ neurons increased wake and reduced REM sleep. Furthermore, given the extended role of the LPBA in respiration and the link between behavioral arousal and breathing rate, we demonstrated that the LPBA but not the peri-LC NPS+ neuronal activation increased respiratory rate. Together, our data suggest that NPS+ neurons of the LPBA represent an unexplored subpopulation regulating breathing, and they are sufficient to recapitulate the sleep/wake phenotypes observed with broad NPS system activation.

RTI-263, a biased neuropeptide S receptor agonist that retains an anxiolytic effect, attenuates cocaine-seeking behavior in rats

Neuropeptide S (NPS) is a neuromodulatory peptide that acts via a G protein-coupled receptor. Centrally administered NPS suppresses anxiety-like behaviors in rodents while producing a paradoxical increase in arousal. In addition, NPS increases drug-seeking behavior when administered during cue-induced reinstatement. Conversely, an NPS receptor (NPSR) antagonist, RTI-118, decreases cocaine-seeking behavior. A biased NPSR ligand, RTI-263, produces anxiolytic-like effects and has memory-enhancing effects similar to those of NPS but without the increase in arousal. In the present study, we show that RTI-263 decreased cocaine seeking by both male and female rats during cue-induced reinstatement. However, RTI-263 did not modulate the animals' behaviors during natural reward paradigms, such as palatable food intake, feeding during a fasting state, and cue-induced reinstatement of sucrose seeking. Therefore, NPSR biased agonists are a potential pharmacotherapy for substance use disorder because of the combined benefits of decreased drug seeking and the suppression of anxiety.

The regulatory role of central neuropeptide-S in locomotion

Central exogenous Neuropeptide-S (NPS) was demonstrated to increase locomotor activity (LMA) in rodent studies. NPS receptor (NPSR) is produced in locomotion-related brain regions including basal ganglia while NPS mediates dopaminergic neurotransmission suggesting that endogenous brain NPS is involved in the regulation of locomotion. Aim of the study was to elucidate whether antagonism of NPSR impairs locomotion and to determine the neurochemical profile of NPSR-expressing cells in basal ganglia network. In the rats received intracerebroventricular injection of selective non-peptide NPSR antagonist ML154 (20 nmol/5 µL) or vehicle, in addition to measurement of catalepsy, motor performance, and motor coordination were evaluated by assessment of LMA and RR test, respectively. The immunoreactivities for NPSR, tyrosine hydroxylase (TH), glutamate decarboxylase 67 (GAD67), and choline acetyltransferase (ChAT) were detected by immunofluorescence in frozen sections. Compared to the control rats, total LMA was significantly declined following ML154 administration. The ML154-injected rats were more prone to fall in rotarod (RR) test, while they exhibited remarkably high catalepsy time. The most robust immunoreactivity for NPSR was detected in globus pallidus externa (GPe), while moderate levels of NPSR expression were observed in substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA), but not in striatum. The NPSR-ir cell bodies were found to express GAD67 in GPe and TH in SNpc and VTA, respectively. NPSR expression was detected in SNpc-projecting pallidal cells. The present findings indicate the regulatory role of central endogenous NPS in the control of locomotion. NPSR may be a potential therapeutic target for the treatment of movement disorders.

Selective breeding of rats for high (HAB) and low (LAB) anxiety-related behaviour: A unique model for comorbid depression and social dysfunctions

Animal models of selective breeding for extremes in emotionality are a strong experimental approach to model psychopathologies. They became indispensable in order to increase our understanding of neurobiological, genetic, epigenetic, hormonal, and environmental mechanisms contributing to anxiety disorders and their association with depressive symptoms or social deficits. In the present review, we extensively discuss Wistar rats selectively bred for high (HAB) and low (LAB) anxiety-related behaviour on the elevated plus-maze. After 30 years of breeding, we can confirm the prominent differences between HAB and LAB rats in trait anxiety, which are accompanied by consistent differences in depressive-like, social and cognitive behaviours. We can further confirm a single nucleotide polymorphism in the vasopressin promotor of HAB rats causative for neuropeptide overexpression, and show that low (or high) anxiety and fear levels are unlikely due to visual dysfunctions. Thus, HAB and LAB rats continue to exist as a reliable tool to study the multiple facets underlying the pathology of high trait anxiety and its comorbidity with depression-like behaviour and social dysfunctions.

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.

Heterogeneous organization of Locus coeruleus: An intrinsic mechanism for functional complexity

Locus coeruleus (LC) is a small nucleus located deep in the brainstem that contains the majority of central noradrenergic neurons, which provide the primary source of noradrenaline (NA) throughout the entire central nervous system (CNS).The release of neurotransmitter NA is considered to modulate arousal, sensory processing, attention, aversive and adaptive stress responses as well as high-order cognitive function and memory, with the highly ramified axonal arborizations of LC-NA neurons sending wide projections to the targeted brain areas. For over 30 years, LC was thought to be a homogeneous nucleus in structure and function due to the widespread uniform release of NA by LC-NA neurons and simultaneous action in several CNS regions, such as the prefrontal cortex, hippocampus, cerebellum, and spinal cord. However, recent advances in neuroscience tools have revealed that LC is probably not so homogeneous as we previous thought and exhibits heterogeneity in various aspects. Accumulating studies have shown that the functional complexity of LC may be attributed to its heterogeneity in developmental origin, projection patterns, topography distribution, morphology and molecular organization, electrophysiological properties and sex differences. This review will highlight the heterogeneity of LC and its critical role in modulating diverse behavioral outcomes.

Correlations between single nucleotide polymorphisms in obsessive-compulsive disorder with the clinical features or response to therapy

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder, in which the patient endures intrusive thoughts or is compelled to perform repetitive or ritualized actions. Many cases of OCD are considered to be familial or heritable in nature. It has been shown that a variety of internal and external risk factors are involved in the pathogenesis of OCD. Among the internal factors, genetic modifications play a critical role in the pathophysiological process. Despite many investigations performed to determine the candidate genes, the precise genetic factors involved in the disease remain largely undetermined. The present review summarizes the single nucleotide polymorphisms that have been proposed to be associated with OCD symptoms, early onset disease, neuroimaging results, and response to therapy. This information could help us to draw connections between genetics and OCD symptoms, better characterize OCD in individual patients, understand OCD prognosis, and design more targeted personalized treatment approaches.

Neuropeptide S (NPS) neurons: Parabrachial identity and novel distributions

Neuropeptide S (NPS) increases wakefulness. A small number of neurons in the brainstem express Nps. These neurons are located in or near the parabrachial nucleus (PB), but we know very little about their ontogeny, connectivity, and function. To identify Nps-expressing neurons within the molecular framework of the PB region, we used in situ hybridization, immunofluorescence, and Cre-reporter labeling in mice. The primary concentration of Nps-expressing neurons borders the lateral lemniscus at far-rostral levels of the lateral PB. Caudal to this main cluster, Nps-expressing neurons scatter through the PB and form a secondary concentration medial to the locus coeruleus (LC). Most Nps-expressing neurons in the PB region are Atoh1-derived, Foxp2-expressing, and mutually exclusive with neurons expressing Calca or Lmx1b. Among Foxp2-expressing PB neurons, those expressing Nps are distinct from intermingled subsets expressing Cck or Pdyn. Examining Nps Cre-reporter expression throughout the brain identified novel populations of neurons in the nucleus incertus, anterior hypothalamus, and lateral habenula. This information will help focus experimental questions about the connectivity and function of NPS neurons.

The association between genetic variability in the NPS/NPSR1 system and chronic stress responses: A gene-environment-(quasi-) experiment

The neuropeptide S (NPS) and its receptor (NPSR1) have been implicated in stress regulation and stress-related disorders. The present study aimed at investigating the association between overall genetic variability in the NPS/NPSR1 system and psychological and cortisol stress regulation in everyday life. Our study was conceptualized as a gene-environment-(quasi-) experiment, a design that facilitates the detection of true GxE interactions. As environmental variable, we used the preparation for the first state examination for law students. In the prospective and longitudinal LawSTRESS project, students were examined at six sampling points over a 13-months period. While students who prepared for the exam and experienced long-lasting and significant stress, formed the stress group, law students experiencing usual study-related workload were assigned to the control group. As phenotypes we assessed changes over time in the cortisol awakening response (CAR; n = 176), perceived stress levels (n = 401), and anxiety symptoms (n = 397). The CAR was assessed at each sampling point immediately upon awakening and 30 as well as 45 min later. Perceived stress levels in daily life were measured by repeated ambulatory assessments and anxiety symptoms were repeatedly assessed with the anxiety subscale of the Hospital Anxiety and Depression Scale. With gene-set analyses we examined the joint association of 936 NPS/NPSR1 single nucleotide polymorphisms with the phenotypes to overcome well known limitations of candidate gene studies. As previously reported, we found a blunted CAR during the exam as well as significant increases in perceived stress levels and anxiety symptoms until the exam in the stress group, compared to the control group. The gene-set analysis did not confirm associations between genetic variability in the NPS/NPSR1 system and changes in perceived stress levels and anxiety symptoms. Regarding the CAR, we found a significant GxE interaction for the area under the curve with respect to the ground (p = .050) and a trend towards a significant effect for the area under the curve with respect to the increase (p = .054). When the analysis was restricted to the SG, associations for both CAR parameters were significant (ps < .050). This finding suggests that the association between genetic variability in the NPS/NPSR1 system and the CAR becomes visible under the environmental condition 'chronic stress exposure'. We conclude that the present study complements findings from animal models and that it provides novel evidence for a modulatory influence of the NPS/NPSR1 system on cortisol regulation in humans.

Neuropeptide S promotes maintenance of newly formed dendritic spines and performance improvement after motor learning in mice

Neuropeptide S (NPS), an endogenous neuropeptide consisting of 20 amino acids, selectively binds and activates G protein-coupled receptor named neuropeptide S receptor (NPSR) to regulate a variety of physiological functions. NPS/NPSR system has been shown to play a pivotal role in regulating learning and memory in rodents. However, it remains unclear that how NPS/NPSR system affects neuronal functions and synaptic plasticity after learning. We found that intracerebroventricular (i.c.v.) injection of NPS promoted performance improvement and reduced sleep duration after motor learning, which could be blocked by pre-treatment with intraperitoneal (i.p.) injection of NPSR antagonist SHA 68. Using intravital two-photon imaging, we examined the effect of NPS on the postsynaptic dendritic spines of layer V pyramidal neurons in the mouse primary motor cortex after motor learning. We found that i.c.v. injection of NPS strengthened learning-induce new spines and facilitated their survival over time. Furthermore, i.c.v. injection of NPS increased calcium activity of apical dendrites and dendritic spines of layer V pyramidal neurons in the mouse primary motor cortex during the running period. These findings suggest that activation of NPSR by NPS increases synaptic calcium activity and learning-related synapse maintenance, thereby contributing to performance improvement after motor learning.

Chronic treatment with escitalopram and venlafaxine affects the neuropeptide S pathway differently in adult Wistar rats exposed to maternal separation

Neuropeptide S (NPS), which is a peptide that is involved in the regulation of the stress response, seems to be relevant to the mechanism of action of antidepressants that have anxiolytic properties. However, to date, there have been no reports regarding the effect of long-term treatment with escitalopram or venlafaxine on the NPS system under stress conditions. This study aimed to investigate the effects of the above-mentioned antidepressants on the NPS system in adult male Wistar rats that were exposed to neonatal maternal separation (MS). Animals were exposed to MS for 360 min. on postnatal days (PNDs) 2-15. MS causes long-lasting behavioral, endocrine and neurochemical consequences that mimic anxiety- and depression-related features. MS and non-stressed rats were given escitalopram or venlafaxine (10mg/kg) IP from PND 69 to 89. The NPS system was analyzed in the brainstem, hypothalamus, amygdala and anterior olfactory nucleus using quantitative RT-PCR and immunohistochemical methods. The NPS system was vulnerable to MS in the brainstem and amygdala. In the brainstem, escitalopram down-regulated NPS and NPS mRNA in the MS rats and induced a tendency to reduce the number of NPS-positive cells in the peri-locus coeruleus. In the MS rats, venlafaxine insignificantly decreased the NPSR mRNA levels in the amygdala and a number of NPSR cells in the basolateral amygdala, and increased the NPS mRNA levels in the hypothalamus. Our data show that the studied antidepressants affect the NPS system differently and preliminarily suggest that the NPS system might partially mediate the pharmacological effects that are induced by these drugs.

Relationship of Neuropeptide S (NPS) with Neurocognitive, Clinical, and Electrophysiological Parameters of Patients during Structured Rehabilitation Therapy for Schizophrenia

Introduction: Neuropeptide S is a biomarker related to various neuropsychiatric and neurocognitive functions. Since the need to improve cognitive functions in schizophrenia is unquestionable, it was valuable to investigate the possible relationships of plasma levels of NPS with neurocognitive, psychopathological and EEG parameters in patients with schizophrenia. Aim: Relationships between the serum NPS level and neurocognitive, clinical, and electrophysiological parameters were investigated in patients diagnosed with schizophrenia who underwent structured rehabilitation therapy. Methods: Thirty-three men diagnosed with schizophrenia were randomized into two groups. The REH group (N16) consisted of patients who underwent structured rehabilitation therapy, the CON group (N17) continued its previous treatment. Additionally, the reference NPS serum results were checked in a group of healthy people (N15). In the study several tests assessing various neurocognitive functions were used: d2 Sustained-Attention Test (d2), Color Trails Test (CTT), Beck Cognitive Insight Scale (BCIS), Acceptance of Illness Scale (AIS), and General Self-Efficacy Scale (GSES). The clinical parameters were measured with Positive and Negative Syndrome Scale (PANSS) and electrophysiological parameters were analyzed with auditory evoked potentials (AEPs) and quantitative electroencephalography (QEEG). The NPS, neurocognitive, clinical, and electrophysiological results of REH and CON groups were recorded at the beginning (T1) and after a period of 3 months (T2). Results: A decreased level of NPS was associated with the improvement in specific complex indices of d2 and BCIS neurocognitive tests, as well as the improvement in the clinical state (PANSS). No correlation was observed between the level of NPS and the results of AEPs and QEEG measurements. Conclusions: A decreased level of NPS is possibly related to the improvement in metacognition and social cognition domains, as well as to clinical improvement during the rehabilitation therapy of patients with schizophrenia.

Neuropeptide S and its receptor NPSR enhance the susceptibility of hosts to pseudorabies virus infection

The neuropeptide S (NPS) and its receptor (NPSR) represent a signaling system in the brain. Increased levels of NPS and NPSR have been observed in PK15 cells and murine brains in response to pseudorabies virus (PRV) infection, but it remains unclear whether elevated levels of NPS and NPSR are involved in the pathogenic process of PRV infection. In this study, the activities of both NPS and NPSR during PRV pathogenesis were explored in vitro and in vivo by reverse transcription polymerase chain reaction (RT-PCR), PCR, real-time quantitative RT-PCR (qRT-PCR), qPCR, TCID50, and Western blotting methods. NPSR-deficient cells were less susceptible to PRV infection, as evidenced by decreased viral production and PRV-glycoprotein E (gE) expression. In vitro studies showed that exogenous NPS promoted the expression of interleukin 6 (IL-6) mRNA but inhibited interferon β (IFN-β) mRNA expression in PK15 cells after PRV infection. In vivo studies showed that NPS-treated mice were highly susceptible to PRV infection, with decreased survival rates and body weights. In addition, NPS-treated mice showed elevated levels of IL-6 mRNA and STAT3 phosphorylation. However, the expression of IFN-β mRNA was greatly decreased after virus challenge. Contrasting results were obtained from the NPSR-ir-treated groups, which further highlighted the effects of NPS. This study revealed that NPS-treated hosts are more susceptible to PRV infection than controls. Moreover, excessive IL-6/STAT3 and defective IFN-β responses in NPS-treated mice may contribute to the pathogenesis of PRV.

A Role for Neuropeptide S in Alcohol and Cocaine Seeking

The neuropeptide S (NPS) is the endogenous ligand of the NPS receptor (NPSR). The NPSR is widely expressed in brain regions that process emotional and affective behavior. NPS possesses a unique physio-pharmacological profile, being anxiolytic and promoting arousal at the same time. Intracerebroventricular NPS decreased alcohol consumption in alcohol-preferring rats with no effect in non-preferring control animals. This outcome is most probably linked to the anxiolytic properties of NPS, since alcohol preference is often associated with high levels of basal anxiety and intense stress-reactivity. In addition, NPSR mRNA was overexpressed during ethanol withdrawal and the anxiolytic-like effects of NPS were increased in rodents with a history of alcohol dependence. In line with these preclinical findings, a polymorphism of the NPSR gene was associated with anxiety traits contributing to alcohol use disorders in humans. NPS also potentiated the reinstatement of cocaine and ethanol seeking induced by drug-paired environmental stimuli and the blockade of NPSR reduced reinstatement of cocaine-seeking. Altogether, the work conducted so far indicates the NPS/NPSR system as a potential target to develop new treatments for alcohol and cocaine abuse. An NPSR agonist would be indicated to help individuals to quit alcohol consumption and to alleviate withdrawal syndrome, while NPSR antagonists would be indicated to prevent relapse to alcohol- and cocaine-seeking behavior.

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.

Relationship of Neuropeptide S with Clinical and Metabolic Parameters of Patients during Rehabilitation Therapy for Schizophrenia

Neuropeptide S (NPS) is a factor associated with the central regulation of body weight, stress, anxiety, learning, memory consolidation, wakefulness-sleep cycle, and anti-inflammatory and neuroplastic effects. Its stress-reducing, anti-anxiety, arousal without anxiety, and pro-cognitive effects represent an interesting option for the treatment of neuropsychiatric disorders. The purpose of the study was to examine the potential associations of NPS levels in the blood with clinical and metabolic parameters during the rehabilitation therapy of patients with schizophrenia. Thirty-three male subjects diagnosed with schizophrenia were randomly divided into two groups. The rehabilitation group (REH, N16) consisted of patients who were subjected to structured, 3-month intensive rehabilitation therapy, and the control group (CON, N17) consisted of patients who were subjected to a standard support mechanism. Both groups continued their pharmacological treatment as usual. The NPS concentration, as well as clinical and metabolic parameters, were compared in both groups. Additionally, a group of healthy (H) males (N15) was tested for NPS reference scores. To look for the specificity and selectivity of the NPS relationship with clinical results, various factor models of the positive and negative syndrome scale (PANSS) were analyzed, including the original PANSS 2/3 model, its modified four-factor version, the male-specific four-factor model, and two five-factorial models validated in large groups in clinical and multi-ethnic studies. Results and conclusions: (1) Structured rehabilitation therapy, compared to unstructured supportive therapy, significantly reduced the level of schizophrenia disorders defined by various factor models derived from PANSS. (2) The clinical improvement within the 3-month rehabilitation therapy course was correlated with a significant decrease in neuropeptide S (NPS) serum level. (3) The excitement/Hostility (E/H) factor, which included schizophrenic symptoms of the psychotic disorganization, was specific and selective for the reduction in serum NPS, which was stable across all analyzed factor models. (4) The long-term relationship between serum NPS and clinical factors was not accompanied by basic metabolic parameters.

Relationship of Neuropeptide S with Clinical and Metabolic Parameters of Patients during Rehabilitation Therapy for Schizophrenia

Neuropeptide S (NPS) is a factor associated with the central regulation of body weight, stress, anxiety, learning, memory consolidation, wakefulness–sleep cycle, and anti-inflammatory and neuroplastic effects. Its stress-reducing, anti-anxiety, arousal without anxiety, and pro-cognitive effects represent an interesting option for the treatment of neuropsychiatric disorders. The purpose of the study was to examine the potential associations of NPS levels in the blood with clinical and metabolic parameters during the rehabilitation therapy of patients with schizophrenia. Thirty-three male subjects diagnosed with schizophrenia were randomly divided into two groups. The rehabilitation group (REH, N16) consisted of patients who were subjected to structured, 3-month intensive rehabilitation therapy, and the control group (CON, N17) consisted of patients who were subjected to a standard support mechanism. Both groups continued their pharmacological treatment as usual. The NPS concentration, as well as clinical and metabolic parameters, were compared in both groups. Additionally, a group of healthy (H) males (N15) was tested for NPS reference scores. To look for the specificity and selectivity of the NPS relationship with clinical results, various factor models of the positive and negative syndrome scale (PANSS) were analyzed, including the original PANSS 2/3 model, its modified four-factor version, the male-specific four-factor model, and two five-factorial models validated in large groups in clinical and multi-ethnic studies. Results and conclusions: (1) Structured rehabilitation therapy, compared to unstructured supportive therapy, significantly reduced the level of schizophrenia disorders defined by various factor models derived from PANSS. (2) The clinical improvement within the 3-month rehabilitation therapy course was correlated with a significant decrease in neuropeptide S (NPS) serum level. (3) The excitement/Hostility (E/H) factor, which included schizophrenic symptoms of the psychotic disorganization, was specific and selective for the reduction in serum NPS, which was stable across all analyzed factor models. (4) The long-term relationship between serum NPS and clinical factors was not accompanied by basic metabolic parameters.

Relationship of Neuropeptide S with Clinical and Metabolic Parameters of Patients during Rehabilitation Therapy for Schizophrenia

Neuropeptide S (NPS) is a factor associated with the central regulation of body weight, stress, anxiety, learning, memory consolidation, wakefulness–sleep cycle, and anti-inflammatory and neuroplastic effects. Its stress-reducing, anti-anxiety, arousal without anxiety, and pro-cognitive effects represent an interesting option for the treatment of neuropsychiatric disorders. The purpose of the study was to examine the potential associations of NPS levels in the blood with clinical and metabolic parameters during the rehabilitation therapy of patients with schizophrenia. Thirty-three male subjects diagnosed with schizophrenia were randomly divided into two groups. The rehabilitation group (REH, N16) consisted of patients who were subjected to structured, 3-month intensive rehabilitation therapy, and the control group (CON, N17) consisted of patients who were subjected to a standard support mechanism. Both groups continued their pharmacological treatment as usual. The NPS concentration, as well as clinical and metabolic parameters, were compared in both groups. Additionally, a group of healthy (H) males (N15) was tested for NPS reference scores. To look for the specificity and selectivity of the NPS relationship with clinical results, various factor models of the positive and negative syndrome scale (PANSS) were analyzed, including the original PANSS 2/3 model, its modified four-factor version, the male-specific four-factor model, and two five-factorial models validated in large groups in clinical and multi-ethnic studies. Results and conclusions: (1) Structured rehabilitation therapy, compared to unstructured supportive therapy, significantly reduced the level of schizophrenia disorders defined by various factor models derived from PANSS. (2) The clinical improvement within the 3-month rehabilitation therapy course was correlated with a significant decrease in neuropeptide S (NPS) serum level. (3) The excitement/Hostility (E/H) factor, which included schizophrenic symptoms of the psychotic disorganization, was specific and selective for the reduction in serum NPS, which was stable across all analyzed factor models. (4) The long-term relationship between serum NPS and clinical factors was not accompanied by basic metabolic parameters.

Escitalopram alters local expression of noncanonical stress-related neuropeptides in the rat brain via NPS receptor signaling

BACKGROUND

Neuropeptide S (NPS) is a multifunctional regulatory factor that exhibits a potent anxiolytic activity in animal models. However, there are no reports dealing with the potential molecular relationships between the anxiolytic activity of selective serotonin reuptake inhibitors (SSRIs) and NPS signaling, especially in the context of novel stress-related neuropeptides action. The present work therefore focused on gene expression of novel stress neuropeptides in the rat brain after acute treatment with escitalopram and in combination with neuropeptide S receptor (NPSR) blockade.

METHODS

Studies were carried out on adult, male Sprague-Dawley rats that were divided into five groups: animals injected with saline (control) and experimental rats treated with escitalopram (at single dose 10 mg/kg daily), escitalopram and SHA-68, a selective NPSR antagonist (at a single dose of 40 mg/kg), SHA-68 alone and corresponding vehicle (solvent SHA-68) control. To measure anxiety-like behavior and locomotor activity the open field test was performed. All individuals were killed under anaesthesia and the whole brain was excised. Total mRNA was isolated from homogenized samples of the amygdala, hippocampus, hypothalamus, thalamus, cerebellum, and brainstem. Real-time PCR was used for estimation of related NPS, NPSR, neuromedin U (NMU), NMU receptor 2 (NMUR2) and nesfatin-1 precursor nucleobindin-2 (NUCB2) gene expression.

RESULTS

Acute escitalopram administration affects the local expression of the examined neuropeptides mRNA in a varied manner depending on brain location. An increase in NPSR and NUCB2 mRNA expression in the hypothalamus and brainstem was abolished by SHA-68 coadministration, while NMU mRNA expression was upregulated after NPSR blockade in the hippocampus and cerebellum.

CONCLUSIONS

The pharmacological effects of escitalopram may be connected with local NPSR-related alterations in NPS/NMU/NMUR2 and nesfatin-1 gene expression at the level of selected rat brain regions. A novel alternative mode of SSRI action can be therefore cautiously proposed.

Effect of Escitalopram on the Number of DCX-Positive Cells and NMUR2 Receptor Expression in the Rat Hippocampus under the Condition of NPSR Receptor Blockade

BACKGROUND

Neuropeptide S (NPS) is a multifunctional regulatory factor that exhibits a potent anxiolytic activity in animal models. However, there are no reports dealing with the potential molecular interactions between the activity of selective serotonin reuptake inhibitors (SSRIs) and NPS signaling, especially in the context of adult neurogenesis and the expression of noncanonical stress-related neuropeptides such as neuromedin U (NMU). The present work therefore focused on immunoexpression of neuromedin U receptor 2 (NMUR2) and doublecortin (DCX) in the rat hippocampus after acute treatment with escitalopram and in combination with selective neuropeptide S receptor (NPSR) blockade.

METHODS

Studies were carried out on adult, male Sprague-Dawley rats that were divided into five groups: animals injected with saline (control) and experimental individuals treated with escitalopram (at single dose 10 mg/kg daily), escitalopram + SHA-68, a selective NPSR antagonist (at single dose 40 mg/kg), SHA-68 alone, and corresponding vehicle control. All animals were sacrificed under halothane anaesthesia. The whole hippocampi were quickly excised, fixed, and finally sliced for general qualitative immunohistochemical assessment of the NPSR and NMUR2 expression. The number of immature neurons was enumerated using immunofluorescent detection of doublecortin (DCX) expression within the subgranular zone (SGZ).

RESULTS

Acute escitalopram administration affects the number of DCX and NMUR2-expressing cells in the adult rat hippocampus. A decreased number of DCX-expressing neuroblasts after treatment with escitalopram was augmented by SHA-68 coadministration.

CONCLUSIONS

Early pharmacological effects of escitalopram may be at least partly connected with local NPSR-related alterations of neuroblast maturation in the rat hippocampus. Escitalopram may affect neuropeptide and DCX-expression starting even from the first dose. Adult neurogenesis may be regulated via paracrine neuropeptide S and NMU-related signaling.

Can Neuropeptide S Be an Indicator for Assessing Anxiety in Psychiatric Disorders?

Neuropeptide S (NPS) is a neuropeptide primarily produced within three brainstem regions including locus coeruleus, trigeminal nerve nucleus, and lateral parabrachial nucleus. NPS is involved in the central regulation of stress, fear, and cognitive integration. NPS is a mediator of behavior, seeking food, and the proliferation of new adipocytes in the setting of obesity. So far, current research of NPS is only limited to animal models; data regarding its functions in humans is still scarce. Animal studies showed that anxiety and appetite might be suppressed by the action of NPS. The discovery of this neuromodulator peptide is effective considering its strong anxiolytic action, which has the potential to be an interesting therapeutic option in treating neuropsychiatric disorders. In this article, we aimed to analyze the pharmaceutical properties of NPS as well as its influence on several neurophysiological aspects-modulation of behavior, association with obesity, as well as its potential application in rehabilitation and treatment of psychiatric disorders.

Roles of Neuropeptides in Sleep-Wake Regulation

Sleep and wakefulness are basic behavioral states that require coordination between several brain regions, and they involve multiple neurochemical systems, including neuropeptides. Neuropeptides are a group of peptides produced by neurons and neuroendocrine cells of the central nervous system. Like traditional neurotransmitters, neuropeptides can bind to specific surface receptors and subsequently regulate neuronal activities. For example, orexin is a crucial component for the maintenance of wakefulness and the suppression of rapid eye movement (REM) sleep. In addition to orexin, melanin-concentrating hormone, and galanin may promote REM sleep. These results suggest that neuropeptides play an important role in sleep–wake regulation. These neuropeptides can be divided into three categories according to their effects on sleep–wake behaviors in rodents and humans. (i) Galanin, melanin-concentrating hormone, and vasoactive intestinal polypeptide are sleep-promoting peptides. It is also noticeable that vasoactive intestinal polypeptide particularly increases REM sleep. (ii) Orexin and neuropeptide S have been shown to induce wakefulness. (iii) Neuropeptide Y and substance P may have a bidirectional function as they can produce both arousal and sleep-inducing effects. This review will introduce the distribution of various neuropeptides in the brain and summarize the roles of different neuropeptides in sleep–wake regulation. We aim to lay the foundation for future studies to uncover the mechanisms that underlie the initiation, maintenance, and end of sleep–wake states.

The influence of early-life and adulthood stressors on brain neuropeptide-S system

Central administered neuropeptide-S (NPS) was shown to reduce stress response in rodents. This study aimed to investigate the alterations in NPS system upon chronic exposure to early-life and adulthood stressors. Newborn pups underwent maternal separation (MS) from postnatal day 1 to 14 comprised of daily 3-h separations. In the adulthood, 90-min of restraint stress was loaded to males as an acute stress (AS) model. For chronic homotypic stress (CHS), same stressor was applied for 5 consecutive days. The changes in the expression and the release of NPS were monitored by immunohistochemistry and microdialysis, respectively. Throughout the CHS, heart rate variability (HRV) was analyzed on a daily basis. The immunoreactivity for NPS receptor (NPSR) was detected in basolateral amygdala (BLA) and hypothalamic paraventricular nucleus (PVN) by immunofluorescence staining. The NPS expression in the brainstem was increased upon AS which was more prominent following CHS, whereas these responses were found to be blunted in MS counterparts. Similar to histological data, the stress-induced release of NPS in BLA was attenuated in MS rats. CHS-induced elevations in sympatho-vagal balance were alleviated in control rats; which was not observed in MS rats. The expression of NPSR in BLA and PVN was down-regulated in MS rats. The brain NPS/NPSR system appears to be susceptible to the early-life stressors and the subsequent chronic stress exposure in adulthood which results in altered autonomic outflow.

Exploring the role of neuropeptides in depression and anxiety

Depression is one of the most prevalent forms of mental disorders and is the most common cause of disability in the Western world. Besides, the harmful effects of stress-related mood disorders on the patients themselves, they challenge the health care system with enormous social and economic impacts. Due to the high proportion of patients not responding to existing drugs, finding new treatment strategies has become an important topic in neurobiology, and there is much evidence that neuropeptides are not only involved in the physiology of stress but may also be clinically important. Based on preclinical trial data, new neuropharmaceutical candidates may target neuropeptides and their receptors and are expected to be essential and valuable tools in the treatment of psychiatric disorders. In the current article, we have summarized data obtained from animal models of depressive disorder and transgenic mouse models. We also focus on previously published research data of clinical studies on corticotropin-releasing hormone (CRH), galanin (GAL), neuropeptide Y (NPY), neuropeptide S (NPS), Oxytocin (OXT), vasopressin (VP), cholecystokinin (CCK), and melanin-concentrating hormone (MCH) stress research fields.

Neuropeptide S Attenuates the Alarm Pheromone-Evoked Defensive and Risk Assessment Behaviors Through Activation of Cognate Receptor-Expressing Neurons in the Posterior Medial Amygdala

Neuropeptide S (NPS) acts by activating its cognate receptor (NPSR). High level expression of NPSR in the posterior medial amygdala suggests that NPS-NPSR system should be involved in regulation of social behaviors induced by social pheromones. The present study was undertaken to investigate the effects of central administration of NPS or with NPSR antagonist on the alarm pheromone (AP)-evoked defensive and risk assessment behaviors in mice. Furthermore, H129-H8, a novel high-brightness anterograde multiple trans-synaptic virus, c-Fos and NPSR immunostaining were employed to reveal the involved neurocircuits and targets of NPS action. The mice exposed to AP displayed an enhancement in defensive and risk assessment behaviors. NPS (0.1–1 nmol) intracerebroventricular (i.c.v.) injection significantly attenuated the AP-evoked defensive and risk assessment behaviors. NPSR antagonist [D-Val⁵]NPS at the dose of 40 nmol completely blocked the effect of 0.5 nmol of NPS which showed the best effective among dose range. The H129-H8-labeled neurons were observed in the bilateral posterodorsal medial amygdala (MePD) and posteroventral medial amygdala (MePV) 72 h after the virus injection into the unilateral olfactory bulb (OB), suggesting that the MePD and MePV receive olfactory information inputs from the OB. The percentage of H129-H8-labeled neurons that also express NPSR were 90.27 ± 3.56% and 91.67 ± 2.46% in the MePD and MePV, respectively. NPS (0.5 nmol, i.c.v.) remarkably increased the number of Fos immunoreactive (-ir) neurons in the MePD and MePV, and the majority of NPS-induced Fos-ir neurons also expressed NPSR. The behavior characteristic of NPS or with [D-Val⁵]NPS can be better replicated in MePD/MePV local injection within lower dose. The present findings demonstrated that NPS, via selective activation of the neurons bearing NPSR in the posterior medial amygdala, attenuates the AP-evoked defensive and risk assessment behaviors in mice.

Centrally Administered Neuropeptide-S Alleviates Gastrointestinal Dysmotility Induced by Neonatal Maternal Separation

BACKGROUND

Neuropeptide-S (NPS) regulates autonomic outflow, stress response, and gastrointestinal (GI) motor functions. This study aimed to investigate the effects of NPS on GI dysmotility induced by neonatal maternal separation (MS).

METHODS

MS was conducted by isolating newborn pups from dams from postnatal day 1 to day 14. In adulthood, rats were also exposed to chronic homotypic stress (CHS). Visceral sensitivity was assessed by colorectal distension-induced abdominal contractions. Gastric emptying (GE) was measured following CHS, whereas fecal output was monitored daily. NPS or NPS receptor (NPSR) antagonist was centrally applied simultaneously with electrocardiography and gastric motility recording. Immunoreactivities for NPS, NPSR, corticotropin-releasing factor (CRF), choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), and c-Fos were assessed by immunohistochemistry.

KEY RESULTS

NPS alleviated the MS-induced visceral hypersensitivity. Under basal conditions, central exogenous or endogenous NPS had no effect on GE and gastric motility. NPS restored CHS-induced gastric and colonic dysmotility in MS rats while increasing sympatho-vagal balance without affecting vagal outflow. NPSR expression was detected in CRF-producing cells of hypothalamic paraventricular nucleus, and central amygdala, but not in Barrington's nucleus. Moreover, NPSR was present in ChAT-expressing neurons in dorsal motor nucleus of the vagus (DMV), and nucleus ambiguus (NAmb) in addition to the TH-positive neurons in C1/A1, and locus coeruleus (LC). Neurons adjacent to the adrenergic cells in LC were found to produce NPS. NPS administration caused c-Fos expression in C1/A1 cells, while no immunoreactivity was detected in DMV or NAmb.

CONCLUSIONS

NPS/NPSR system might be a novel target for the treatment of stress-related GI dysmotility.

Neuropeptides and Behaviors: How Small Peptides Regulate Nervous System Function and Behavioral Outputs

One of the reasons that most multicellular animals survive and thrive is because of the adaptable and plastic nature of their nervous systems. For an organism to survive, it is essential for the animal to respond and adapt to environmental changes. This is achieved by sensing external cues and translating them into behaviors through changes in synaptic activity. The nervous system plays a crucial role in constantly evaluating environmental cues and allowing for behavioral plasticity in the organism. Multiple neurotransmitters and neuropeptides have been implicated as key players for integrating sensory information to produce the desired output. Because of its simple nervous system and well-established neuronal connectome, C. elegans acts as an excellent model to understand the mechanisms underlying behavioral plasticity. Here, we critically review how neuropeptides modulate a wide range of behaviors by allowing for changes in neuronal and synaptic signaling. This review will have a specific focus on feeding, mating, sleep, addiction, learning and locomotory behaviors in C. elegans. With a view to understand evolutionary relationships, we explore the functions and associated pathophysiology of C. elegans neuropeptides that are conserved across different phyla. Further, we discuss the mechanisms of neuropeptidergic signaling and how these signals are regulated in different behaviors. Finally, we attempt to provide insight into developing potential therapeutics for neuropeptide-related disorders.

Neuropeptide S (NPS) and its receptor (NPSR1) in chickens: cloning, tissue expression, and functional analysis

Neuropeptide S (NPS) and its receptor neuropeptide S receptor 1 (NPSR1) have been suggested to regulate many physiological processes in the central nervous system (CNS), such as arousal, anxiety, and food intake in mammals and birds, however, the functionality and tissue expression of this NPS-NPSR1 system remain unknown in birds. Here, we cloned NPS and NPSR1 cDNAs from the chicken brain and reported their functionality and tissue expression. The cloned chicken NPS is predicted to encode a mature NPS peptide of 20 amino acids, which shows a remarkable sequence identity (∼94%) among tetrapod species examined, while NPSR1 encodes a receptor of 373 amino acids conserved across vertebrates. Using cell-based luciferase reporter systems, we demonstrated that chicken NPS could potently activate NPSR1 expressed in vitro and thus stimulates multiple signaling pathways, including calcium mobilization, cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathways, indicating that NPS actions could be mediated by NPSR1 in birds. Quantitative real-time PCR revealed that NPS and NPSR1 are widely expressed in chicken tissues, including the hypothalamus, and NPSR1 expression is likely controlled by a promoter upstream exon 1, which shows strong promoter activities in cultured DF-1 cells. Taken together, our data provide the first proof that the avian NPS-NPSR1 system is functional and helps to explore the conserved role of NPS and NPSR1 signaling in tetrapods.

Central neuropeptide-S administration alleviates stress-induced impairment of gastric motor functions through orexin-A

BACKGROUND/AIMS

The novel brain peptide neuropeptide-S (NPS) is produced exclusively by a small group of cells adjacent to the noradrenergic locus coeruleus. The NPSR mRNA has been detected in several brain areas involved in stress response and autonomic outflow, such as amygdala and hypothalamus, suggesting that central NPS may play a regulatory role in stress-induced changes in gastrointestinal (GI) motor functions. In rodents, exogenous central NPS was shown to inhibit stress-stimulated fecal output. Moreover, exogenous NPS was demonstrated to activate hypothalamic neurons that produce orexin-A (OXA), which has been shown to stimulate postprandial gastric motor functions via central vagal pathways. Therefore, we tested whether OXA mediates the NPS-induced alterations in gastric motor functions under stressed conditions.

MATERIALS AND METHODS

We investigated the effect of central exogenous NPS on solid gastric emptying (GE) and gastric postprandial motility in acute restraint stress (ARS)-loaded conscious rats. The OXA receptor antagonist SB-334867 was administered centrally prior to the central NPS injection. The expression of NPSR in the hypothalamus and dorsal vagal complex was analyzed by immunofluorescence.

RESULTS

Central administration of NPS restored the ARS-induced delayed GE and uncoordinated postprandial antro-pyloric contractions. The alleviative effect of NPS on GE was abolished by pretreatment of the OX1R antagonist SB-334867. In addition to hypothalamus, NPSR was detected in the dorsal motor nucleus of vagus, which suggest a direct stimulatory action of exogenous NPS on gastric motility.

CONCLUSION

NPS may be a novel candidate for the treatment of stress-related gastric disorders.

Identification of a Novel Neuropeptide S Receptor Antagonist Scaffold Based on the SHA-68 Core

Activation of the neuropeptide S receptor (NPSR) system has been shown to produce anxiolytic-like actions, arousal, and enhance memory consolidation, whereas blockade of the NPSR has been shown to reduce relapse to substances of abuse and duration of anesthetics. We report here the discovery of a novel core scaffold (+) N-benzyl-3-(2-methylpropyl)-1-oxo-3-phenyl-1H,3H,4H,5H,6H,7H-furo[3,4-c]pyridine-5-carboxamide with potent NPSR antagonist activity in vitro. Pharmacokinetic parameters demonstrate that 14b reaches pharmacologically relevant levels in plasma and the brain following intraperitoneal (i.p.) administration, but is cleared rapidly from plasma. Compound 14b was able to block NPS (0.3 nmol)-stimulated locomotor activity in C57/Bl6 mice at 3 mg/kg (i.p.), indicating potent in vivo activity for the structural class. This suggests that 14b can serve as a useful tool for continued mapping of the pharmacological functions of the NPS receptor system.

Some Twist of Molecular Circuitry Fast Forwards Overnight Sleep Hours: A Systematic Review of Natural Short Sleepers' Genes

This systematic review focuses on different genetic mutations identified in studies on natural short sleepers, who would not be ill-defined as one type of sleep-related disorder. The reviewed literature is from databases such as PubMed, PMC, Scopus, and ResearchGate. Due to the rare prevalence, the number of studies conducted on natural short sleepers is limited. Hence, searching the search of databases was done without any date restriction and included animal studies, since mouse and fly models share similarities with human sleep behaviors. Of the 12 articles analyzed, four conducted two types of studies, animal and human (cross-sectional or randomized-controlled studies), to testify the effects of human mutant genes in familial natural short sleepers via transgenic mouse or fly models. The remaining eight articles mainly focused on one type of study each: animal study (four articles), cross-sectional study (two articles), review (one article), and case report (one article). Hence, those articles brought different perspectives on the natural short sleep phenomenon by identifying intrinsic factors like DEC2, NPSR1, mGluR1, and β1-AR mutant genes. Natural short sleep traits in either point-mutations or single null mutations in those genes have been examined and confirmed its intrinsic nature in affected individuals without any related health concerns. Finally, this review added a potential limitation in these studies, mainly highlighting intrinsic causes since one case study reported an extrinsically triggered short sleep behavior in an older man without any family history. The overall result of the review study suggests that the molecular mechanisms tuned by identified sleep genes can give some potential points of therapeutic intervention in future studies.

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.