Neuropeptide S reduces propofol- or ketamine-induced slow wave states through activation of cognate receptors in the rat

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.

Roles of Neuropeptide S in Anesthesia, Analgesia, and Sleep

Neuropeptide S (NPS) is an endogenous peptide that regulates various physiological functions, such as immune functions, anxiety-like behaviors, learning and memory, the sleep–wake rhythm, ingestion, energy balance, and drug addiction. These processes include the NPS receptor (NPSR1). The NPS–NPSR1 system is also significantly associated with the onset of disease, as well as these physiologic functions. For example, NPS is involved in bronchial asthma, anxiety and awakening disorders, and rheumatoid arthritis. In this review, among the various functions, we focus on the role of NPS in anesthesia-induced loss of consciousness; analgesia, mainly by anesthesia; and sleep–wakefulness. Progress in the field regarding the functions of endogenous peptides in the brain, including NPS, suggests that these three domains share common mechanisms. Further NPS research will help to elucidate in detail how these three domains interact with each other in their functions, and may contribute to improving the quality of medical care.

Gene polymorphisms (rs324957, rs324981) in NPSR1 are associated with increased risk of primary insomnia: A cross-sectional study

Neuropeptide S and neuropeptide S receptor (NPSR1) are associated with sleep regulation. Herein, the possible contribution of 6 polymorphisms in NPSR1 on the chromosome to primary insomnia (PI) and objective sleep phenotypes was investigated.The study included 157 patients with PI and 133 age- and sex-matched controls. All subjects were investigated by polysomnography for 3 consecutive nights. The genotyping of 6 polymorphisms was carried out by polymerase chain reaction-restriction fragment length polymorphism method.A significant difference was detected for rs324957 and rs324981 between PI and controls. The PI patients had a higher frequency of AA than controls in rs324957 (P = .02) and rs324981 (P = .04). However, for other single nucleotide polymorphisms (rs323922, rs324377, rs324396, and rs324987), no significant differences were observed between PI patients and controls. There were 2 different allelic combinations that were associated with PI susceptibility (CATGTC, GCCAAT) and its risk factor. A significant difference in sleep latency was observed among 3 genotype carriers of NPSR1 gene polymorphism rs324957 in PI group (P = .04), with carriers of the A/A genotype having the longest sleep latency (mean ± SD: 114.80 ± 58.27), followed by the A/G genotype (112.77 ± 46.54) and the G/G genotype (92.12 ± 42.72).This study provided the evidence that the NPSR1 gene polymorphisms (rs324957, rs324981) might be susceptibility loci for PI. Further studies are needed to explore the role of NPSR1 gene polymorphisms in molecular mechanisms of PI in a larger sample size.

Neuropeptide S Displays as a Key Neuromodulator in Olfactory Spatial Memory

Neuropeptide S (NPS) is an endogenous peptide recently recognized to be presented in the brainstem and believed to play an important role in maintaining memory. The deletion of NPS or NPS receptor (NPSR) in mice shows a deficit in memory formation. Our recent studies have demonstrated that central administration of NPS facilitates olfactory function and ameliorates olfactory spatial memory impairment induced by muscarinic cholinergic receptor antagonist and N-methyl-D-aspartate receptor antagonist. However, it remains to be determined if endogenous NPS is an indispensable neuromodulator in the control of the olfactory spatial memory. In this study, we examined the effects of NPSR peptidergic antagonist [D-Val5]NPS (10 and 20 nmol, intracerebroventricular) and nonpeptidergic antagonist SHA 68 (10 and 50 mg/kg, intraperitoneal) on the olfactory spatial memory using computer-assisted 4-hole-board olfactory spatial memory test in mice. Furthermore, immunofluorescence was employed to identify the distributions of c-Fos and NPSR immunoreactive (-ir) neurons in olfactory system and hippocampal formation known to closely relate to the olfactory spatial memory. [D-Val5]NPS dosing at 20 nmol and SHA 68 dosing at 50 mg/kg significantly decreased the number of visits to the 2 odorants interchanged spatially, switched odorants, in recall trial, and simultaneously reduced the percentage of Fos-ir in NPSR-ir neurons, which were densely distributed in the anterior olfactory nucleus, piriform cortex, subiculum, presubiculum, and parasubiculum. These findings suggest that endogenous NPS is a key neuromodulator in olfactory spatial memory.

Association of NPSR1 rs324981 polymorphism and treatment response to antidepressants in Chinese Han population with generalized anxiety disorder

In previous studies, neuropeptide S (NPS) and its cognate receptor (NPSR) have been involved in the pathogenesis of anxiety disorders in previous studies. Here, we aimed to investigate the association of NPSR1 polymorphism with generalized anxiety disorder (GAD) and its treatment response in Chinese Han population. Three hundred and thirty seven patients and one hundred and seventy seven healthy controls were involved in our study for 8 weeks. Further, Hamilton Anxiety Scale (HAMA) was used to assess anxiety symptom at baseline and the 1st, 2nd, 4th, 8th week. And all participants were genotyped for NPSR1 (rs324981) variants by polymerase chain reaction. Using Repeated-measures analysis, it showed significant reduction on HAMA scores in patients treated with escitalopram (F = 1.03, P = 0.362) and venlafaxine (F = 0.27, P = 0.763) respectively through 8 weeks treatment. Additionally, patients with AA and TT homozygous genotypes treated with venlafaxine XR had a higher reduction of HAMA scores compared to AT heterozygotic carriers (F = 4.18, P = 0.004), while no significant differences were found in patients treated with escitalopram (F = 1.05, P = 0.383). Thus, our study provides preliminary evidence that NPSR1 AA and TT homozygous genotypes have better treatment responses to venlafaxine XR in Chinese GAD patients, but not to escitalopram. Further studies are needed to verify the observation.

The ventromedial hypothalamic nucleus plays an important role in anxiolytic-like effect of neuropeptide S

Neuropeptide S (NPS), the endogenous neuropeptide ligand of NPSR, has been reported to regulate anxiety-related behavior involved in multiple brain regions, including amygdale, locus coeruleus and Barrington's nucleus. However, little research has been conducted on the anxiolytic-like behaviors of NPS on the hypothalamus, which was an important area in defensive behavior. Here, we investigated a role of hypothalamus in anxiolytic-like behaviors of NPS. We found that NPSR protein of mouse distributed mainly in the ventromedial hypothalamus (VMH). And in the single prolonged stress model (SPS), the results showed that NPS mRNA of the mice exposed to SPS was significantly higher than control, while NPSR mRNA was remarkable lower than control in hypothalamus. Further studies found that NPS intra-VMH infusion dose-dependently (1, 10 and 100pmol) induced anxiolytic effects, using elevated plus maze and open field tests. These anxiolytic effects could be blocked by NPSR antagonist (SHA68), but not by picrotoxin (a GABA_A receptor antagonist) and sacolfen (a GABA_B receptor antagonist). Meanwhile, our data showed that the expression of c-Fos was significantly increased in VMH after NPS delivered into the lateral ventricles. These results cast a new light on the hypothalamic nucleus in the anxiolytic-like effect of NPS system.

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.