Association of serum levels of leptin, ghrelin, and adiponectin in schizophrenic patients and healthy controls

Differences in metabolic biomarkers in people with schizophrenia who are of Mexican descent compared to non-Hispanic whites

Metabolic dysfunction is highly prevalent and contributes to premature mortality among people with schizophrenia (PwS), especially in Hispanic/Latino/a/x/e PwS, compared to non-Hispanic White (NHW) PwS. This study evaluated the relative contributions of Mexican descent and schizophrenia diagnosis to metabolic biomarker levels. This cross-sectional study included 115 PwS and 102 non-psychiatric comparison (NC) participants - English-speakers aged 26-66 years, 27% Mexican descent, and 52% women across both groups. Assessments included evaluations of BMI, psychopathology, and fasting metabolic biomarkers. We used ANOVA analyses to compare metabolic outcomes between diagnostic and ethnic subgroups, linear regression models to examine associations between Mexican descent and metabolic outcomes, and Spearman's correlations to examine relationships between metabolic outcomes and illness-related variables in PwS. Mexican PwS had higher hemoglobin A1c levels, insulin resistance, and body mass index than NHW PwS. Mexican descent was associated with higher hemoglobin A1c levels, insulin resistance, body mass index, and leptin levels, controlling for age, sex, depression, education, and smoking. Among Mexican PwS, worse negative symptoms were associated with greater insulin resistance. These findings support the possibility of ethnicity-based differences in metabolic dysregulation, though further investigation is warranted to create targeted health interventions for Hispanic PwS.

Leptin Methylation and mRNA Expression Associated With Psychopathology in Schizophrenia Inpatients

Leptin involved in the regulation of dopaminergic neurons of the central nervous system may confirm the hypothesis of neurodevelopment in schizophrenic patients. However, specific genetic mechanisms are undefined. Therefore, we aimed to explore the regulation of DNA methylation of leptin promoters and mRNA expression in patients with schizophrenia. A cross-sectional study enrolled 40 patients and 40 healthy controls from the Beijing Huilongguan Hospital in China. The leptin methylation levels and mRNA expression were examined by highly sensitive mass spectrometry based on the MassARRAY System and real-time quantitative polymerase chain reaction (qPCR). The Positive and Negative Symptoms Scale (PANSS) was applied to estimate the clinical symptoms of patients. The LEP-CpG7 and CpG15 methylation in patients were significantly higher than in healthy controls (P < 0.05). The LEP-CpG11, CpG33.34.35, CpG36 methylation, and mRNA expression decreased significantly in patients compared with healthy controls (P < 0.05). After controlling gender, age, BMI, dose of antipsychotic and duration of illness, LEP-CpG7 methylation was negatively associated with PANSS positive symptoms subscore (r = -0.485, P = 0.005). In addition, LEP-mRNA expression was negatively correlated with PANSS total score (r = -0.385, P = 0.03) and positive subscale (r = -0.392, P = 0.026). Nevertheless, only the LEP-CpG7 methylation level remained negatively correlated to the PANSS positive subscore following multiple stepwise regression (β = -17.071, P = 0.037). These results suggest that leptin methylation and mRNA expression might contribute to the pathogenesis of schizophrenia. LEP-CpG7 methylation may be negatively associated with positive symptoms in patients with schizophrenia.

Immunoendocrine Peripheral Effects Induced by Atypical Antipsychotics

Atypical antipsychotics (AAP) or second-generation antipsychotics are the clinical option for schizophrenia treatment during acute psychoses, but they are also indicated for maintenance during lifetime, even though they are being used for other psychiatric conditions in clinical practice such as affective disorders and autism spectrum disorder, among others. These drugs are differentiated from typical antipsychotics based on their clinical profile and are a better choice because they cause fewer side effects regarding extrapyramidal symptoms (EPS). Even though they provide clear therapeutic benefits, AAP induce peripheral effects that trigger phenotypic, functional, and systemic changes outside the Central Nervous System (CNS). Metabolic disease is frequently associated with AAP and significantly impacts the patient's quality of life. However, other peripheral changes of clinical relevance are present during AAP treatment, such as alterations in the immune and endocrine systems as well as the intestinal microbiome. These less studied alterations also have a significant impact in the patient's health status. This manuscript aims to revise the peripheral immunological, endocrine, and intestinal microbiome changes induced by AAP consumption recommended in the clinical guidelines for schizophrenia and other psychiatric disorders.

The association of serum nesfatin-1 and ghrelin levels with metabolic syndrome in patients with schizophrenia

Nesfatin-1 and ghrelin are two hormones which has opposite effects and play role in food intake. This study was planned on the idea that both metabolic syndrome and psychiatric disorders are associated with nesfatin-1 and ghrelin. In this study, it was aimed to investigate the levels of ghrelin and nesfatin-1 in patients with schizophrenia, by taking confounding factor as the metabolic syndrome (MS). 55 patients with schizophrenia and 33 healthy controls were included in the study.11 out of the 55 patients (%20) has MS. Serum ghrelin and nesfatin-1 levels of schizophrenia patients with MS have been compared with both healthy controls and schizophrenia patients without MS. Patients with schizophrenia had significantly higher serum nesfatin-1 levels compared to healthy controls. But serum ghrelin levels was not different in both groups. Serum nesfatin-1 concentrations were significantly higher in the schizophrenia patients with MS (10.51-350.8pg/ml) with respect to the healthy control group (4.86-68.91pg/ml). There was no significant statistical difference between the three groups in terms of ghrelin levels. Our findings suggests that, MS presence also contributed to significantly high levels of nesfatin-1 level. Nesfatin-1 may have a part in a novel studies regarding the treatment of schizophrenia and its metabolic effects.

Are leptin levels increased among people with schizophrenia versus controls? A systematic review and comparative meta-analysis

OBJECTIVE

Leptin may play a role in the pathophysiology of schizophrenia and it remains unclear if levels are raised compared to controls. Therefore, we performed a systematic review and meta-analysis comparing leptin levels among people with schizophrenia and controls.

METHOD

Two authors independently searched major electronic databases from inception until June 2015 for studies measuring blood leptin levels among people with schizophrenia and controls. Random effects meta-analysis calculating hedges g and 95% confidence intervals (CI) and meta-regression analyses were conducted.

RESULTS

Twenty-seven articles representing 1674 individuals with schizophrenia (34.6 ± 6.8 years, 55% male (0-100%), BMI 25.2 ± 3.1) and 2033 controls (33.9 ± 7.0 years, 51% male (0-100%), BMI=24.1 ± 2.1) were included. Across all studies, leptin levels may be marginally higher in schizophrenia (g=0.164, 95% CI -0.014-0.341, p=0.07, Q=217, p<0.01), particularly when one outlier was removed (g=0.196, 95% CI 0.210-0.370, p=0.02) and when we included the smallest effect size from studies with multiple comparisons (g=0.318, 95% CI 0.125-0.510, p=0.001). Leptin levels were higher in multi-episode schizophrenia (g=0.245, 95% CI 0.058-0.433, p=0.01) and females (g=0.557 95% CI 0.16-0.954, p=0.006). Subgroup analyses revealed leptin levels may be higher in participants taking second-generation antipsychotics compared to controls. Multivariate meta-regression demonstrated a lower percentage of males (β=-0.0064, 95% CI -0.0129 to -0.0002, p=0.05), but not BMI, moderated the results.

CONCLUSION

Our results suggest that schizophrenia is associated with increased blood leptin levels compared to controls, which may not be entirely attributable to antipsychotic medication or BMI. Other illness related and lifestyle choices may play a pivotal role.

Second-generation antipsychotics and adiponectin levels in schizophrenia: A comparative meta-analysis

People with schizophrenia treated with second-generation antipsychotics (SGAs) have lower plasma adiponectin levels, as compared with general population, that may lead to metabolic abnormalities. However, the contribution of different SGAs on adiponectin dysregulation is still unclear. The objective of this systematic review and meta-analysis was to estimate differences in adiponectin levels among people with schizophrenia treated with different SGAs. We systematically searched for observational studies published up to March 2015 in main electronic databases. Different SGAs were included if data on adiponectin were available from at least three different samples involving as a minimum five participants per treatment arm. Standardized mean differences with relevant 95% confidence intervals were generated. I(2) was used to test heterogeneity among studies. Eight studies were included with data suitable for carrying out four different comparisons: Clozapine vs. Olanzapine (including n=877 individuals with schizophrenia); Clozapine vs. Risperidone (n=660); Olanzapine vs. Risperidone (n=738); Quetiapine vs. Risperidone (n=186). There were no differences on adiponectin levels between people taking Clozapine and those taking Olanzapine (p=0.86), but high heterogeneity was detected (I(2)=82%). Both individuals taking Clozapine (p<0.001; I(2)=0%) and those taking Olanzapine (p=0.02; I(2)=9%), but not subjects treated with Quetiapine (p=0.47; I(2)=0%), had adiponectin levels significantly lower than people taking Risperidone. Our findings are consistent with previous evidence showing greater metabolic abnormalities attributable to Clozapine and Olanzapine, as compared with other SGAs. Although mechanisms whereby both these SGAs influence adiponectin remain unexplained, its reduction might mediate relevant abnormalities. Prospective evaluations of long-term effects of different SGAs on adiponectin are needed.

Plasma adiponectin levels in schizophrenia and role of second-generation antipsychotics: a meta-analysis

BACKGROUND

People with schizophrenia are more likely than general population to suffer from metabolic abnormalities, with second-generation antipsychotics (SGAs) increasing the risk. Low plasma adiponectin levels may lead to metabolic dysregulations but evidence in people with schizophrenia, especially for the role of SGAs, is still inconclusive.

OBJECTIVE

To compare plasma adiponectin levels between people with schizophrenia and healthy controls, and to estimate the relative effect of schizophrenia and SGAs on adiponectin.

METHODS

We performed a systematic review and meta-analysis of observational studies published up to 13 June 2014 in main electronic databases. Pooled standardized mean differences (SMDs) between index and control groups were generated. Appropriate subanalyses and additional subgroup analyses were carried out.

RESULTS

Data from 2735 individuals, 1013 with and 1722 without schizophrenia, respectively, were analysed. Schizophrenia was not associated with lower adiponectin levels (SMD of -0.28, 95%CI: -0.59, 0.04; p=0.09). However, individuals with schizophrenia taking SGAs had plasma levels significantly lower than controls (p=0.002), which was not the case of drug free/drug naïve subjects (p=0.52). As regards single antipsychotic drugs clozapine (p<0.001) and olanzapine (p=0.04)--but not risperidone (p=0.88)--were associated with adiponectin levels lower than controls.

CONCLUSIONS

People with schizophrenia per se may not have levels of adiponectin lower than controls, though treatment with SGAs is associated with this metabolic abnormality. This bears clinical significance because of hypoadiponectinemia involvement in cardiovascular diseases, even if mechanisms whereby SGAs affect adiponectin remain unexplained. Longitudinal studies evaluating long-term effects of SGAs on adiponectin are needed.

Differential effects of olanzapine and clozapine on plasma levels of adipocytokines and total ghrelin

Second-generation antipsychotics (SGAs) have been associated with an increased liability for weight gain and metabolic side effects. Among SGAs, clozapine and olanzapine had great liability to induce weight gain and metabolic adverse reactions. Leptin, adiponectin, and total ghrelin play important roles in energy homeostasis and are suggested to be biomarkers of metabolic disturbances. The purpose of the present study was to investigate the differential effects of antipsychotics (olanzapine and clozapine) on the levels of adipocytokines (leptin and adiponectin) and total ghrelin. Three hundred and thirty-three patients with schizophrenia under clozapine or olanzapine monotherapy were recruited. Control participants were recruited from a healthy community population based on a health investigation (N=119). Fasting blood samples for glucose, cholesterol, triglycerides, leptin, adiponectin, and total ghrelin were analyzed. There were significant differences in the levels of cholesterol, triglycerides, and glucose between these three groups. Post hoc comparisons showed that the olanzapine group had the highest levels of cholesterol and triglycerides. The levels of leptin, adiponectin, and total ghrelin were also significantly different between the three groups after controlling age and body mass index (BMI). Post hoc comparisons showed that the olanzapine group had the lowest levels of adiponectin and total ghrelin. The present study found that the uses of olanzapine and clozapine were associated with changes in adipocytokines and total ghrelin, even after adjusting potential confounding factors. Olanzapine had greater influences on adiponectin and total ghrelin than clozapine. The changes in adipocytokines and total ghrelin were a direct effect of antipsychotics on hormonal pathways of energy homeostasis, rather than the result of weight gain.

Plasma omentin levels in drug-free patients with schizophrenia

AIMS

We aimed to investigate plasma omentin concentrations in non-obese, drug-free patients with schizophrenia in comparison with healthy volunteers.

METHOD

Thirty-two patients with schizophrenia and 33 control subjects were recruited. Plasma omentin levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Plasma levels of omentin (ng/ml) were found to be markedly lower in patients with schizophrenia (median = 7.7, 25th percentile = 6.3, 75th percentile = 604.9) than in controls (median = 486, 25th percentile = 326, 75th percentile = 794.2, p < 0.01). No significant difference was found between drug-free (n = 23) and drug-naive (n = 9) patients with respect to plasma omentin levels. Omentin concentrations correlated negatively with severity of illness, suggesting that patients with more severe pathology had lower fasting levels of omentin (n = 32; r = -0.387; p = 0.029).

CONCLUSION

The present results suggest that plasma omentin levels are decreased in physically healthy, non-obese, antipsychotic-free patients with schizophrenia when compared with physically and mentally healthy individuals. To our knowledge, this is the first study that demonstrated the association between omentin and schizophrenia.

Blockade of growth hormone secretagogue receptor 1A signaling by JMV 2959 attenuates the NMDAR antagonist, phencyclidine-induced impairments in prepulse inhibition

RATIONALE

Schizophrenic-spectrum patients commonly display deficits in preattentive information processing as evidenced, for example, by disrupted prepulse inhibition (PPI), a measure of sensorimotor gating. Similar disruptions in PPI can be induced in rodents and primates by the psychotomimetic drug phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor. Mounting evidence suggests that the hunger hormone ghrelin and its constitutively active receptor influences neuronal circuits involved in the regulation of mood and cognition.

OBJECTIVES

In the present series of experiments, we investigated the effects of ghrelin and the growth hormone secretagogue receptor (GHS-R1A) neutral antagonist, JMV 2959, on acoustic startle responses (ASR), PPI, and PCP-induced alterations in PPI.

RESULTS

Intraperitoneal (i.p.) administration of ghrelin (0.033, 0.1, and 0.33 mg/kg) did not alter the ASR or PPI in rats. Conversely, i.p. injection of JMV 2959 (1, 3, and 6 mg/kg), dose dependently decreased the ASR and increased PPI. Pretreatment with JMV 2959 at a dose with no effect on ASR or PPI per se, completely blocked PCP-induced (2 mg/kg) deficits in PPI while pretreatment with the highest dose of ghrelin did not potentiate or alter PPI responses of a sub-threshold dose of PCP (0.75 mg/kg).

CONCLUSION

These findings indicate that the GHS-R1A is involved in specific behavioral effects of PCP and may have relevance for patients with schizophrenia.

Leptin and the brain: influences on brain development, cognitive functioning and psychiatric disorders

Receptors of leptin, the prototypical adipokine, are expressed throughout the cortex and several other areas of the brain. Although typically studied for its role in energy intake and expenditure, leptin plays a critical role in many other neurocognitive processes and interacts with various other hormones and neurotransmitters to perform these functions. Here, we review the literature on how leptin influences brain development, neural degradation, Alzheimer's disease, psychiatric disorders, and more complicated cognitive functioning and feeding behaviors. We also discuss modulators of leptin and the leptin receptor as they relate to normal cognitive functioning and may mediate some of the actions of leptin in the brain. Although we are beginning to better understand the critical role leptin plays in normal cognitive functioning, there is much to be discovered.

Peptides from adipose tissue in mental disorders

Adipose tissue is a dynamic endocrine organ that is essential to regulation of metabolism in humans. A new approach to mental disorders led to research on involvement of adipokines in the etiology of mental disorders and mood states and their impact on the health status of psychiatric patients, as well as the effects of treatment for mental health disorders on plasma levels of adipokines. There is evidence that disturbances in adipokine secretion are important in the pathogenesis, clinical presentation and outcome of mental disorders. Admittedly leptin and adiponectin are involved in pathophysiology of depression. A lot of disturbances in secretion and plasma levels of adipokines are observed in eating disorders with a significant impact on the symptoms and course of a disease. It is still a question whether observed dysregulation of adipokines secretion are primary or secondary. Moreover findings in this area are somewhat inconsistent, owing to differences in patient age, sex, socioeconomic status, smoking habits, level of physical activity, eating pathology, general health or medication. This was the rationale for our detailed investigation into the role of the endocrine functions of adipose tissue in mental disorders. It seems that we are continually at the beginning of understanding of the relation between adipose tissue and mental disorders.

Metabolomic profiling of schizophrenia patients at risk for metabolic syndrome

Second-generation antipsychotics (SGAs) are commonly used to treat schizophrenia. However, SGAs cause metabolic disturbances that can manifest as metabolic syndrome (MetS) in a subset of patients. The causes for these metabolic disturbances remain unclear. We performed a comprehensive metabolomic profiling of 60 schizophrenia patients undergoing treatment with SGAs that puts them at high (clozapine, olanzapine), medium (quetiapine, risperidone), or low (ziprasidone, aripiprazole) risk for developing MetS, compared to a cohort of 20 healthy controls. Multiplex immunoassays were used to measure 13 metabolic hormones and adipokines in plasma. Mass spectrometry was used to determine levels of lipids and polar metabolites in 29 patients and 10 controls. We found that levels of insulin and tumor necrosis factor alpha (TNF-α) were significantly higher (p < 0.005) in patients at medium and high risk for MetS, compared to controls. These molecules are known to be increased in individuals with high body fat content and obesity. On the other hand, adiponectin, a molecule responsible for control of food intake and body weight, was significantly decreased in patients at medium and high risk for MetS (p < 0.005). Further, levels of dyacylglycerides (DG), tryacylglycerides (TG) and cholestenone were increased, whereas α-Ketoglutarate and malate, important mediators of the tricarboxylic acid (TCA) cycle, were significantly decreased in patients compared to controls. Our studies suggest that high- and medium-risk SGAs are associated with disruption of energy metabolism pathways. These findings may shed light on the molecular underpinnings of antipsychotic-induced MetS and aid in design of novel therapeutic approaches to reduce the side effects associated with these drugs.

Genetics of antipsychotic-induced weight gain: update and current perspectives

Antipsychotic medications are used to effectively treat various symptoms for different psychiatric conditions. Unfortunately, antipsychotic-induced weight gain (AIWG) is a common side effect that frequently results in obesity and secondary medical conditions. Twin and sibling studies have indicated that genetic factors are likely to be highly involved in AIWG. Over recent years, there has been considerable progress in this area, with several consistently replicated findings, as well as the identification of new genes and implicated pathways. Here, we will review the most recent genetic studies related to AIWG using the Medline database (PubMed) and Google Scholar. Among the steadiest findings associated with AIWG are serotonin 2C receptors (HTR2C) and leptin promoter gene variants, with more recent studies implicating MTHFR and, in particular, MC4R genes. Additional support was reported for the HRH1, BDNF, NPY, CNR1, GHRL, FTO and AMPK genes. Notably, some of the reported variants appear to have relatively large effect sizes. These findings have provided insights into the mechanisms involved in AIWG and will help to develop predictive genetic tests in the near future.

The impact of leptin on perinatal development and psychopathology

Leptin has long been associated with metabolism as it is a critical regulator of both food intake and energy expenditure, but recently, leptin dysregulation has been proposed as a mechanism of psychopathology. This review discusses the evidence supporting a role for leptin in mental health disorders and describes potential mechanisms that may underlie this association. Leptin plays a critical role in pregnancy and in fetal growth and development. Leptin's role and profile during development is examined in available human studies, and the validity of applying studies conducted in animal models to the human population are discussed. Rodents experience a postnatal leptin surge, which does not occur in humans or larger animal models. This suggests that further research using large mammal models, which have a leptin profile across pregnancy and development similar to humans, are of high importance. Maternal obesity and hyperleptinemia correlate with increased leptin levels in the umbilical cord, placenta, and fetus. Leptin levels are thought to impact fetal brain development; likely by activating proinflammatory cytokines that are known to impact many of the neurotransmitter systems that regulate behavior. Leptin is likely involved in behavioral regulation as leptin receptors are widely distributed in the brain, and leptin influences cortisol release, the mesoaccumbens dopamine pathway, serotonin synthesis, and hippocampal synaptic plasticity. In humans, both high and low levels of leptin are reported to be associated with psychopathology. This inconsistency is likely due to differences in the metabolic state of the study populations. Leptin resistance, which occurs in the obese state, may explain how both high and low levels of leptin are associated with psychopathology, as well as the comorbidity of obesity with numerous mental illnesses. Leptin resistance is likely to influence disorders such as depression and anxiety where high leptin levels have been correlated with symptomatology. Schizophrenia is also associated with both low and high leptin levels. However, as anti-psychotics pharmacotherapy induces weight gain, which elevates leptin levels, drug-naïve populations are needed for further studies. Elevated circulating leptin is consistently found in childhood neurodevelopmental disorders including autism spectrum disorders and Rhett disorder. Further, studies on the impact of leptin and leptin resistance on psychopathology and neurodevelopmental disorders are important directions for future research. Studies examining the mechanisms by which exposure to maternal obesity and hyperleptinemia during fetal development impact brain development and behavior are critical for the health of future generations.

Ghrelin-Derived Peptides: A Link between Appetite/Reward, GH Axis, and Psychiatric Disorders?

Psychiatric disorders are often associated with metabolic and hormonal alterations, including obesity, diabetes, metabolic syndrome as well as modifications in several biological rhythms including appetite, stress, sleep-wake cycles, and secretion of their corresponding endocrine regulators. Among the gastrointestinal hormones that regulate appetite and adapt the metabolism in response to nutritional, hedonic, and emotional dysfunctions, at the interface between endocrine, metabolic, and psychiatric disorders, ghrelin plays a unique role as the only one increasing appetite. The secretion of ghrelin is altered in several psychiatric disorders (anorexia, schizophrenia) as well as in metabolic disorders (obesity) and in animal models in response to emotional triggers (psychological stress …) but the relationship between these modifications and the physiopathology of psychiatric disorders remains unclear. Recently, a large literature showed that this key metabolic/endocrine regulator is involved in stress and reward-oriented behaviors and regulates anxiety and mood. In addition, preproghrelin is a complex prohormone but the roles of the other ghrelin-derived peptides, thought to act as functional ghrelin antagonists, are largely unknown. Altered ghrelin secretion and/or signaling in psychiatric diseases are thought to participate in altered appetite, hedonic response and reward. Whether this can contribute to the mechanism responsible for the development of the disease or can help to minimize some symptoms associated with these psychiatric disorders is discussed in the present review. We will thus describe (1) the biological actions of ghrelin and ghrelin-derived peptides on food and drugs reward, anxiety and depression, and the physiological consequences of ghrelin invalidation on these parameters, (2) how ghrelin and ghrelin-derived peptides are regulated in animal models of psychiatric diseases and in human psychiatric disorders in relation with the GH axis.