Acoustic startle response and sensorimotor gating in a genetic mouse model for the Y1 receptor

Neuropeptide Y in first-episode schizophrenia: is there any sex differences in the pathogeneses of schizophrenia?

Objective

This study investigated relationships between Neuropeptide Y levels and severity of psychiatric symptoms in first-episode schizophrenia patients, and explore the sexual heterogeneity in them.

Methods

We recruited 115 first-episode schizophrenia patients and 58 matched healthy controls, and measured serum Neuropeptide Y levels of them at baseline and again after 10 weeks of risperidone treatment in patient group. Patients were also evaluated with the Positive and Negative Symptoms Scale (PANSS) to reveal the severity of symptoms.

Results

95 patients completed the whole experiment. We find that mean Neuropeptide Y levels at baseline were significantly higher in patients than in controls (p<0.001), no matter in males or females. In males, there are positive correlations between Neuropeptide Y levels and PANSS scores at baseline (p<0.01), and between the change of them (p<0.05). However, we do not find these correlations in female patients. Furthermore, the interaction terms of NPY × sex were highly significant taking PANSS as dependent variable(p<0.001).

Conclusion

Neuropeptide Y plays a significant role in the pathogenesis of schizophrenia. In male patients, Neuropeptide Y is positively correlated with the severity of symptoms, while this correlation is not found in females. Continued efforts are needed to determine the sexual dimorphism in pathogeneses of schizophrenia.

Cross talk about the role of Neuropeptide Y in CNS disorders and diseases

A peptide composed of a 36 amino acid called Neuropeptide Y (NPY) is employed in a variety of physiological processes to manage and treat conditions affecting the endocrine, circulatory, respiratory, digestive, and neurological systems. NPY naturally binds to G-protein coupled receptors, activating the Y-receptors (Y1-Y5 and y6). The findings on numerous therapeutic applications of NPY for CNS disease are presented in this review by the authors. New targets for treating diseases will be revealed by medication combinations that target NPY and its receptors. This review is mainly focused on disorders such as anxiety, Alzheimer's disease, Parkinson's disease, Huntington's disease, Machado Joseph disease, multiple sclerosis, schizophrenia, depression, migraine, alcohol use disorder, and substance use disorder. The findings from the preclinical studies and clinical studies covered in this article may help create efficient therapeutic plans to treat neurological conditions on the one hand and psychiatric disorders on the other. They may also open the door to the creation of novel NPY receptor ligands as medications to treat these conditions.

Impaired hormonal regulation of appetite in schizophrenia: A narrative review dissecting intrinsic mechanisms and the effects of antipsychotics

Cardiometabolic diseases are the main contributor of reduced life expectancy in patients with schizophrenia. It is now widely accepted that antipsychotic treatment plays an important role in the development of obesity and its consequences. However, some intrinsic mechanisms need to be taken into consideration. One of these mechanisms might be related to impaired hormonal regulation of appetite in this group of patients. In this narrative review, we aimed to dissect impairments of appetite-regulating hormones attributable to intrinsic mechanisms and those related to medication effects. Early hormonal alterations that might be associated with intrinsic mechanisms include low levels of leptin and glucagon-like peptide-1 (GLP-1) together with elevated insulin levels in first-episode psychosis (FEP) patients. However, evidence regarding low GLP-1 levels in FEP patients is based on one large study. In turn, multiple-episode schizophrenia patients show elevated levels of insulin, leptin and orexin A together with decreased levels of adiponectin. In addition, patients receiving olanzapine may present with low ghrelin levels. Post mortem studies have also demonstrated reduced number of neuropeptide Y neurons in the prefrontal cortex of patients with schizophrenia. Treatment with certain second-generation antipsychotics may also point to these alterations. Although our understanding of hormonal regulation of appetite in schizophrenia has largely been improved, several limitations and directions for future studies need to be addressed. This is of particular importance since several novel pharmacological interventions for obesity and diabetes have already been developed and translation of these developments to the treatment of cardiometabolic comorbidities in schizophrenia patients is needed.

The genetics of anxiety-related negative valence system traits

NIMH's Research Domain Criteria (RDoC) domain of negative valence systems (NVS) captures constructs of negative affect such as fear and distress traditionally subsumed under the various internalizing disorders. Through its aims to capture dimensional measures that cut across diagnostic categories and are linked to underlying neurobiological systems, a large number of phenotypic constructs have been proposed as potential research targets. Since "genes" represent a central "unit of analysis" in the RDoC matrix, it is important for studies going forward to apply what is known about the genetics of these phenotypes as well as fill in the gaps of existing knowledge. This article reviews the extant genetic epidemiological data (twin studies, heritability) and molecular genetic association findings for a broad range of putative NVS phenotypic measures. We find that scant genetic epidemiological data is available for experimentally derived measures such as attentional bias, peripheral physiology, or brain-based measures of threat response. The molecular genetic basis of NVS phenotypes is in its infancy, since most studies have focused on a small number of candidate genes selected for putative association to anxiety disorders (ADs). Thus, more research is required to provide a firm understanding of the genetic aspects of anxiety-related NVS constructs. © 2016 Wiley Periodicals, Inc.

First Behavioural Characterisation of a Knockout Mouse Model for the Transforming Growth Factor (TGF)-β Superfamily Cytokine, MIC-1/GDF15

Macrophage inhibitory cytokine-1 (MIC-1), also known as growth differentiation factor 15 (GDF15), is a stress response cytokine. MIC-1/GDF15 is secreted into the cerebrospinal fluid and increased levels of MIC-1/GDF15 are associated with a variety of diseases including cognitive decline. Furthermore, Mic-1/Gdf15 knockout mice (Mic-1 KO) weigh more, have increased adiposity, associated with increased spontaneous food intake, and exhibit reduced basal energy expenditure and physical activity. The current study was designed to comprehensively determine the role of MIC-1/GDF15 on behavioural domains of male and female knockout mice including locomotion, exploration, anxiety, cognition, social behaviours, and sensorimotor gating. Mic-1 KO mice exhibited a task-dependent increase in locomotion and exploration and reduced anxiety-related behaviours across tests. Spatial working memory and social behaviours were not affected by Mic-1/Gdf15 deficiency. Interestingly, knockout mice formed an increased association with the conditioned stimulus in fear conditioning testing and also displayed significantly improved prepulse inhibition. Overall sex effects were evident for social behaviours, fear conditioning, and sensorimotor gating. This is the first study defining the role of Mic-1/Gdf15 in a number of behavioural domains. Whether the observed impact is based on direct actions of Mic-1/Gdf15 deficiency on the CNS or whether the behavioural effects are mediated by indirect actions on e.g. other neurotransmitter systems must be clarified in future studies.

Targeting the Neuropeptide Y System in Stress-related Psychiatric Disorders

Repeated, extreme, or traumatic stressors can elicit pathological effects leading to many negative physical and psychological outcomes. Stressors can precipitate the onset of psychiatric diseases, or exacerbate pre-existing disorders including various anxiety and mood disorders. As stressors can negatively impact human psychiatric health, it is essential to identify neurochemicals that may confer protection from the negative sequelae of repeated or extreme stress exposure. Elucidating the neurobiological underpinnings of stress resilience will enhance our ability to promote resilience to, or recovery from, stress-related psychiatric disease. Herein, we will review the evidence for neuropeptide Y as an endogenous mediator of resilience and its potential relevance for the treatment of stress-related psychiatric diseases.

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Overview of neuropeptide Y and receptor subtypes in the central nervous system.

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Alterations of neuropeptide Y in human stress-related psychiatric disorders.

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Evidence for neuropeptide Y in resilience to stress-related emotionality in rodent behavioral models.

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Pharmacotherapeutic implications for neuropeptide Y in the treatment of stress-related psychiatric disorders.

Serum neuropeptide Y in accident survivors with depression or posttraumatic stress disorder

Although neuropeptide Y (NPY) has received attention for its potential anti-depressive and anti-anxiety effect, evidence in humans has been limited. This study aimed to clarify the relationships between serum NPY and depressive disorders, and posttraumatic stress disorder (PTSD) in accident survivors. Depressive disorders and PTSD were diagnosed by structural interviews at 1-month follow-up, and serum NPY was measured at the first assessment and 1-month follow-up. Analysis of variance was used to investigate significance of the differences identified. Furthermore, resilience was measured by self-report questionnaires. Multiple linear regression analyses were used to examine the relationship between resilience and serum NPY. Three hundred accident survivors participated in the assessment at the first assessment, and 138 completed the assessment at 1-month follow-up. Twenty-six participants had major depressive disorder and 6 had minor depressive disorder. Nine participants had PTSD and 16 had partial PTSD. No relationship existed between serum NPY and depressive disorders, PTSD, and resilience. The results of cannot be compared with those of NPY in the central nervous system (CNS), but these findings might be due to the nature of depression and PTSD in accident survivors. Further studies are needed to examine the relationships between NPY in CNS and depression and PTSD.

Neuropeptide Y and posttraumatic stress disorder

Resiliency to the adverse effects of extraordinary emotional trauma on the brain varies within the human population. Accordingly, some people cope better than others with traumatic stress. Neuropeptide Y (NPY) is a 36-amino-acid peptide transmitter abundantly expressed in forebrain limbic and brain stem areas that regulate stress and emotional behaviors. Studies largely in rodents demonstrate a role for NPY in promoting coping with stress. Moreover, accruing data from the genetic to the physiological implicate NPY as a potential 'resilience-to-stress' factor in humans. Here, we consolidate findings from preclinical and clinical studies of NPY that are of relevance to stress-associated syndromes, most prototypically posttraumatic stress disorder (PTSD). Collectively, these data suggest that reduced central nervous system (CNS) NPY concentrations or function may be associated with PTSD. We also link specific symptoms of human PTSD with extant findings in the NPY field to reveal potential physiological contributions of the neuropeptide to the disorder. In pursuit of understanding the physiological basis and treatment of PTSD, the NPY system is an attractive target.

A neuropeptide Y variant (rs16139) associated with major depressive disorder in replicate samples from Chinese Han population

Objective

This study aimed to investigate the single nucleotide polymorphisms (SNPs) of neuropeptide Y (NPY) and major depressive disorder (MDD) in Chinese Han population.

Design

Prospective and randomized studies were carried out.

Patients

A total of 700 patients (324 male and 376 female; mean age = 40±14.9 years) with depression who met the diagnostic criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and 673 healthy controls (313 male and 360 female; mean age = 41.9±17.2 years) were used to investigate the relationship between SNPs of NPY and the pathogenesis of MDD. A total of 417 patients (195 male and 202 female; mean age = 36±14.2 years) diagnosed with MDD and 314 healthy controls (153 male and 161 female; mean age = 37.9±14.2 years) from Chinese Han population were used to verify the relationship between SNPs of NPY and the pathogenesis of MDD.

Intervention and outcome

Ligase detection reactions were performed to detect the SNP sites of NPY. A series of statistical methods was carried out to investigate the correlation between the NPY gene SNP and MDD.

Results

Statistical analysis showed a significant correlation between the SNP sites rs16139 in NPY and the morbidity of depression. Patients with MDD have a lower frequency of A-allele in rs16139 in replicate samples from Chinese Han population. However, the frequency varied between male and female patients.

Conclusion

The gene polymorphism loci rs16139 was closely related to MDD in Chinese Han population.

Genetic models of sensorimotor gating: relevance to neuropsychiatric disorders

Sensorimotor gating, or the ability of a sensory event to suppress a motor response, can be measured operationally via prepulse inhibition (PPI) of the startle response. PPI is deficient in schizophrenia patients as well as other neuropsychiatric disorders, can be measured across species, and has been used widely as a translational tool in preclinical neuropharmacological and genetic research. First developed to assess drug effects in pharmacological and developmental models, PPI has become one of the standard behavioral measures in genetic models of schizophrenia and other neuropsychiatric disorders that exhibit PPI deficits. In this chapter we review the literature on genetic models of sensorimotor gating and discuss the utility of PPI as a tool in phenotyping mutant mouse models. We highlight the approaches to genetic mouse models of neuropsychiatric disease, discuss some of the important caveats to these approaches, and provide a comprehensive table covering the more recent genetic models that have evaluated PPI.

An interaction between a neuropeptide Y gene polymorphism and early adversity modulates endocrine stress responses

Interindividual variability in the regulation of the human stress system accounts for a part of the individual's liability to stress-related diseases. These differences are influenced by environmental and genetic factors. Early childhood adversity is a well-studied environmental factor affecting an individual's stress response which has been shown to be modulated by gene-environment interaction (GxE). Neuropeptide Y (NPY) plays a role in stress regulation and genetic variation in NPY may influence stress responses. In this study, we analyzed the association of a common variant in the NPY gene promoter, rs16147, with cortisol and ACTH responses to acute psychosocial stress in young adults from the Mannheim Study of Children at Risk (MARS), an ongoing epidemiological cohort study following the outcome of early adversity from birth into adulthood. We found evidence of a GxE interaction between rs16147 and early adversity significantly affecting HPA axis responses to acute psychosocial stress. These findings suggest that the neurobiological mechanisms linking early adverse experience and later neuroendocrine stress regulation are modulated by a gene variant whose functional relevance is documented by increasing convergent evidence from in vitro, animal and human studies.