Olanzapine-induced endoplasmic reticulum stress and inflammation in the hypothalamus were inhibited by an ER stress inhibitor 4-phenylbutyrate

Olanzapine's effects on hypothalamic transcriptomics and kinase activity

Olanzapine is a second-generation antipsychotic that disrupts metabolism and is associated with an increased risk of type 2 diabetes. The hypothalamus is a key region in the control of whole-body metabolic homeostasis. The objective of the current study was to determine how acute peripheral olanzapine administration affects transcription and serine/threonine kinase activity in the hypothalamus. Hypothalamus samples from rats were collected following the pancreatic euglycemic clamp, thereby allowing us to study endpoints under steady state conditions for plasma glucose and insulin. Olanzapine stimulated pathways associated with inflammation, but diminished pathways associated with the capacity to combat endoplasmic reticulum stress and G protein-coupled receptor activity. These pathways represent potential targets to reduce the incidence of type 2 diabetes in patients taking antipsychotics.

Activation of the PERK-CHOP signaling pathway during endoplasmic reticulum stress contributes to olanzapine-induced dyslipidemia

Olanzapine (OLZ) is a widely prescribed antipsychotic drug with a relatively ideal effect in the treatment of schizophrenia (SCZ). However, its severe metabolic side effects often deteriorate clinical therapeutic compliance and mental rehabilitation. The peripheral mechanism of OLZ-induced metabolic disorders remains abstruse for its muti-target activities. Endoplasmic reticulum (ER) stress is implicated in cellular energy metabolism and the progression of psychiatric disorders. In this study, we investigated the role of ER stress in the development of OLZ-induced dyslipidemia. A cohort of 146 SCZ patients receiving OLZ monotherapy was recruited, and blood samples and clinical data were collected at baseline, and in the 4th week, 12th week, and 24th week of the treatment. This case-control study revealed that OLZ treatment significantly elevated serum levels of endoplasmic reticulum (ER) stress markers GRP78, ATF4, and CHOP in SCZ patients with dyslipidemia. In HepG2 cells, treatment with OLZ (25, 50 μM) dose-dependently enhanced hepatic de novo lipogenesis accompanied by SREBPs activation, and simultaneously triggered ER stress. Inhibition of ER stress by tauroursodeoxycholate (TUDCA) and 4-phenyl butyric acid (4-PBA) attenuated OLZ-induced lipid dysregulation in vitro and in vivo. Moreover, we demonstrated that activation of PERK-CHOP signaling during ER stress was a major contributor to OLZ-triggered abnormal lipid metabolism in the liver, suggesting that PERK could be a potential target for ameliorating the development of OLZ-mediated lipid dysfunction. Taken together, ER stress inhibitors could be a potentially effective intervention against OLZ-induced dyslipidemia in SCZ.

HFD-exacerbated Metabolic Side Effects of Olanzapine Are Suppressed by ER Stress Inhibitor

OBJECTIVE

Numerous schizophrenic patients are suffering from obesity primarily attributed to antipsychotic medication and poor dietary habits. This study investigated the progressive deterioration of olanzapine-induced metabolic disorders in the presence of a high-fat diet (HFD) and explored the involvement of endoplasmic reticulum (ER) stress.

METHODS

Female Sprague-Dawley rats fed on a standard chow diet or HFD were treated with olanzapine (3 mg/kg/day) and the ER stress inhibitor 4-phenylbutyric acid (4-PBA, 1 and 0.5 g/kg/day) for 8 days. Changes in body weight, food intake, and plasma lipids were assessed. Hepatic fat accumulation was evaluated using oil red O staining. Western blotting and immunofluorescence assays were employed to examine the expression of ER stress markers, NOD-like receptor pyrin domain-containing protein 3 (NLRP3), and proopiomelanocortin (POMC) in the hypothalamus or liver.

RESULTS

Compared to olanzapine alone, olanzapine+HFD induced greater weight gain, increased hyperlipidemia, and enhanced hepatic fat accumulation (P<0.05). Co-treatment with 4-PBA exhibited a dose-dependent inhibition of these effects (P<0.05). Further mechanistic investigations revealed that olanzapine alone activated ER stress, upregulated NLRP3 expression in the hypothalamus and liver, and downregulated hypothalamic POMC expression. The HFD exacerbated these effects by 50%-100%. Moreover, co-administration of 4-PBA dose-dependently attenuated the olanzapine+HFD-induced alterations in ER stress, NLRP3, and POMC expression in the hypothalamus and liver (P<0.05).

CONCLUSION

HFD worsened olanzapine-induced weight gain and lipid metabolic disorders, possibly through ER stress-POMC and ER stress-NLRP3 signaling. ER stress inhibitors could be effective in preventing olanzapine+HFD-induced metabolic disorders.

Vitamin D Receptor Activation Attenuates Olanzapine-Induced Dyslipidemia in Mice Through Alleviating Hepatic Endoplasmic Reticulum Stress

The involvement of vitamin D (VD) signaling in atypical antipsychotics (AAPs)-induced metabolic disturbances has been previously established. This study aims to elucidate the role of VD in maintaining endoplasmic reticulum (ER) homeostasis and its impact on AAPs-induced metabolic adverse effects. Female C57BL/6 mice receive either calcitriol or vehicle one week prior to co-treatment with olanzapine (OLZ) for an additional four weeks. Metabolic parameters, hepatic ER homeostasis, and the SREBPs pathway are assessed through biochemical assays and protein expression profiling. HepG2 cells are transfected with vitamin D receptor (VDR) siRNA for VDR knockdown. OLZ-treated HepG2 cells are exposed to calcitriol to examine its effects on SREBPs and the unfolded protein response (UPR) pathways. VDR activation by calcitriol reduces OLZ-induced hepatic ER stress, leading to decreased SREBPs activity and lipid accumulation. Conversely, the knockdown of VDR in HepG2 cells diminishes the protective effects of calcitriol against OLZ-induced ER stress and SREBPs activation. This resulted in sustained UPR activation, elevated cleaved SREBPs levels, and increased lipid accumulation. These findings highlight an essential role of VDR signaling in the beneficial effects of VD on OLZ-induced metabolic side effects. Targeting VDR to resolve ER stress is likely an applicable therapeutic strategy for AAPs-induced metabolic disturbances.

Hypothalamic JNK1-hepatic fatty acid synthase axis mediates a metabolic rewiring that prevents hepatic steatosis in male mice treated with olanzapine via intraperitoneal: Additional effects of PTP1B inhibition

Olanzapine (OLA), a widely used second-generation antipsychotic (SGA), causes weight gain and metabolic alterations when administered orally to patients. Recently, we demonstrated that, contrarily to the oral treatment which induces weight gain, OLA administered via intraperitoneal (i.p.) in male mice resulted in body weight loss. This protection was due to an increase in energy expenditure (EE) through a mechanism involving the modulation of hypothalamic AMPK activation by higher OLA levels reaching this brain region compared to those of the oral treatment. Since clinical studies have shown hepatic steatosis upon chronic treatment with OLA, herein we further investigated the role of the hypothalamus-liver interactome upon OLA administration in wild-type (WT) and protein tyrosine phosphatase 1B knockout (PTP1B-KO) mice, a preclinical model protected against metabolic syndrome. WT and PTP1B-KO male mice were fed an OLA-supplemented diet or treated via i.p. Mechanistically, we found that OLA i.p. treatment induces mild oxidative stress and inflammation in the hypothalamus in a JNK1-independent and dependent manner, respectively, without features of cell dead. Hypothalamic JNK activation up-regulated lipogenic gene expression in the liver though the vagus nerve. This effect concurred with an unexpected metabolic rewiring in the liver in which ATP depletion resulted in increased AMPK/ACC phosphorylation. This starvation-like signature prevented steatosis. By contrast, intrahepatic lipid accumulation was observed in WT mice treated orally with OLA; this effect being absent in PTP1B-KO mice. We also demonstrated an additional benefit of PTP1B inhibition against hypothalamic JNK activation, oxidative stress and inflammation induced by chronic OLA i.p. treatment, thereby preventing hepatic lipogenesis. The protection conferred by PTP1B deficiency against hepatic steatosis in the oral OLA treatment or against oxidative stress and neuroinflammation in the i.p. treatment strongly suggests that targeting PTP1B might be also a therapeutic strategy to prevent metabolic comorbidities in patients under OLA treatment in a personalized manner.

A stay of execution: ATF4 regulation and potential outcomes for the integrated stress response

ATF4 is a cellular stress induced bZIP transcription factor that is a hallmark effector of the integrated stress response. The integrated stress response is triggered by phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 complex that can be carried out by the cellular stress responsive kinases; GCN2, PERK, PKR, and HRI. eIF2α phosphorylation downregulates mRNA translation initiation en masse, however ATF4 translation is upregulated. The integrated stress response can output two contradicting outcomes in cells; pro-survival or apoptosis. The mechanism for choice between these outcomes is unknown, however combinations of ATF4 heterodimerisation partners and post-translational modifications have been linked to this regulation. This semi-systematic review article covers ATF4 target genes, heterodimerisation partners and post-translational modifications. Together, this review aims to be a useful resource to elucidate the mechanisms controlling the effects of the integrated stress response. Additional putative roles of the ATF4 protein in cell division and synaptic plasticity are outlined.

Endovascular Stem Cell Therapy Promotes Neuronal Remodeling to Enhance Post Stroke Recovery by Alleviating Endoplasmic Reticulum Stress Modulated by BDNF Signaling

BACKGROUND AND PURPOSE

The impact of increased BDNF expression in brain by endovascular delivered mesenchymal stem cells (MSCs) post stroke towards modulating endoplasmic reticulum (ER) stress mediated neuronal remodeling has not been directly studied. Therefore, the present study investigates ER stress mediated neuronal remodeling following IA MSCs infusion in rodent model of ischemic stroke.

METHODS

Ovariectomized Sprague Dawley rats were subjected to MCAO followed by 1 × 10⁵ IA MSCs administration at 6 h. Infarct and functional outcomes at different time points post-stroke were evaluated. Further, various genes and protein expression studies were performed to determine the underlying mechanisms of the effect of IA MSCs towards ER stress mediated neuronal remodeling.

RESULTS

Post-stroke IA MSCs administration significantly increased BDNF expression and decreased ER stress markers expression at day 1 post-stroke. A gradual rise in the expression of growth associate protein-43 (GAP 43) and spinophilin were observed at 7, 14- and 28-days post-stroke indicating an increase in neuronal remodeling towards functional restoration.

CONCLUSIONS

The results suggest that IA MSCs post-stroke can modulate neuronal remodeling by BDNF-mediated reduction in ER stress that contribute towards functional recovery.

Topical phenylbutyrate antagonizes NF-κB signaling and resolves corneal inflammation

Chronic inflammation of the immune privileged cornea originating from viral or nonviral conditions results in significant vision loss. Topical corticosteroids are the common treatments for corneal inflammation, but the drugs cause serious and potentially blinding side effects in the long term. Therefore, new standalone and/or synergistic anti-inflammatory therapies with lower side effects are desperately needed. Here, we show that the aromatic fatty acid phenylbutyrate (PBA) acts as a potent inhibitor of inflammation in preclinical ocular-inflammation models. PBA prevents the transcription as well as translation of pro-inflammatory cytokines by LPS and poly(I:C) via persistent inhibition of NF-κB signaling. PBA quickens the resolution of ocular inflammation in mice by decreasing corneal thickness and immune cell infiltration. More importantly, PBA can synergize with the dexamethasone to antagonize NF-κB signaling at lower drug concentrations. Our results demonstrate that PBA therapy exerts previously unreported anti-inflammatory effects in the eye and facilitates corneal healing during persistent inflammation.

The role of hypothalamic endoplasmic reticulum stress in schizophrenia and antipsychotic-induced weight gain: A narrative review

Schizophrenia (SCZ) is a serious mental illness that affects 1% of people worldwide. SCZ is associated with a higher risk of developing metabolic disorders such as obesity. Antipsychotics are the main treatment for SCZ, but their side effects include significant weight gain/obesity. Despite extensive research, the underlying mechanisms by which SCZ and antipsychotic treatment induce weight gain/obesity remain unclear. Hypothalamic endoplasmic reticulum (ER) stress is one of the most important pathways that modulates inflammation, neuronal function, and energy balance. This review aimed to investigate the role of hypothalamic ER stress in SCZ and antipsychotic-induced weight gain/obesity. Preliminary evidence indicates that SCZ is associated with reduced dopamine D2 receptor (DRD2) signaling, which significantly regulates the ER stress pathway, suggesting the importance of ER stress in SCZ and its related metabolic disorders. Antipsychotics such as olanzapine activate ER stress in hypothalamic neurons. These effects may induce decreased proopiomelanocortin (POMC) processing, increased neuropeptide Y (NPY) and agouti-related protein (AgRP) expression, autophagy, and leptin and insulin resistance, resulting in hyperphagia, decreased energy expenditure, and central inflammation, thereby causing weight gain. By activating ER stress, antipsychotics such as olanzapine activate hypothalamic astrocytes and Toll-like receptor 4 signaling, thereby causing inflammation and weight gain/obesity. Moreover, evidence suggests that antipsychotic-induced ER stress may be related to their antagonistic effects on neurotransmitter receptors such as DRD2 and the histamine H1 receptor. Taken together, ER stress inhibitors could be a potential effective intervention against SCZ and antipsychotic-induced weight gain and inflammation.

Attenuation of Olanzapine-Induced Endoplasmic Reticulum Stress Improves Insulin Secretion in Pancreatic Beta Cells

Second-generation antipsychotics (SGAs), in particular, olanzapine and clozapine, have been associated with the development of type 2 diabetes mellitus (T2D) and metabolic syndrome in individuals with schizophrenia. In this context, beta cell dysfunction is a plausible mechanism by which SGAs cause T2D. Herein, we analyzed the direct effects of olanzapine, a commonly prescribed SGA with diabetogenic properties, on the INS-1 (821/13) beta cell line and isolated pancreatic islets. Treatment of INS-1 beta cells with non-toxic concentrations of olanzapine (3–6 μM) during 4 h activated endoplasmic reticulum (ER) stress-mediated signaling by increasing PERK/eIF2α phosphorylation, IRE-1 phosphorylation and XBP-1 splicing. Moreover, glucose-stimulated insulin secretion (GSIS) was inhibited when olanzapine was present for 16 h. The insulin secretory function of INS-1 cells was restored by inhibiting olanzapine-induced ER stress with tauroursodeoxycholic acid (TUDCA). Similar effects of olanzapine with or without TUDCA on ER-stress-mediated signaling and GSIS were found in pancreatic islets from female mice. Our results indicate that early activation of ER stress in pancreatic beta cells is a potential mechanism behind the alterations in glucose homeostasis induced by olanzapine.

NLRP3/Caspase-1-Mediated Pyroptosis of Astrocytes Induced by Antipsychotics Is Inhibited by a Histamine H1 Receptor-Selective Agonist

Emerging data indicate that antipsychotic treatment causes brain volume loss and astrocyte death, but the mechanisms remain elusive. Pyroptosis, inflammatory cell death characterized by the formation of inflammatory bodies, increased expression of nod-like receptor proteins (NLRPs) such as NLRP3, and activation of caspases and gasdermin D (GSDMD) are largely associated with innate immunity, inflammation, and cell injury/death. However, the main effect of antipsychotics on astrocyte pyroptotic signaling and the molecular mechanisms remain obscure. In the present study, 72-h treatment with olanzapine, quetiapine, risperidone, or haloperidol significantly decreased the viability of astrocytes. Twenty-four hour treatment with olanzapine, quetiapine, risperidone, or haloperidol dose-dependently increased the protein expression of astrocytic NLRP3, NLRP6, caspase-1, caspase-4, and GSDMD. Co-treatment with a histamine H1 receptor agonist, 2-(3-trifluoromethylphenyl) histamine (FMPH), dose-dependently reduced the increased expression of NLRP3, caspase-1 and GSDMD induced by olanzapine, quetiapine, risperidone, or haloperidol. Moreover, olanzapine, quetiapine, risperidone, or haloperidol treatment induced pore formation in the membranes of astrocytes, and these effects were inhibited by FMPH co-treatment. Taken together, antipsychotic treatment activated astrocyte pyroptotic signaling, and these effects may be related to antipsychotic-induced astrocyte death. H1 receptor activation is an effective treatment strategy to suppress antipsychotic-induced astrocyte pyroptosis and inflammation.

Icariin inhibits the expression of IL-1β, IL-6 and TNF-α induced by OGD/R through the IRE1/XBP1s pathway in microglia

CONTEXT

Icariin (ICA), a flavonol glycoside extracted from Epimedium brevicornum Maxim (Berberidaceae), has been proven to inhibit inflammatory response in ischaemic rats in our laboratory's previous work. However, its underlying mechanism is still unclear.

OBJECTIVE

This study investigates the effects of ICA on endoplasmic reticulum (ER) stress mediated inflammation induced by cerebral ischaemia-reperfusion (I/R) injury in vitro.

MATERIALS AND METHODS

The primary cultured microglia were treated with oxygen-glucose deprivation (OGD) for 2 h followed by a 24 h reoxygenation. ICA (0.37, 0.74 and 1.48 μmol/L) administration was performed 1 h prior OGD and acting through 2 h OGD. The control group was cultured in normal conditions. At 24 h after reoxygenation, the expression of IRE1α, XBP1u, XBP1s, NLRP3 and caspase-1 was detected by western blotting (WB) and quantitative real-time (qRT) PCR; the expression of p-IRE1α was examined by WB; the expression of IL-1β, IL-6 and TNF-α was measured by WB and enzyme-linked immunosorbent assay (ELISA).

RESULTS

ICA (0.37, 0.74 and 1.48 μmol/L) reduced the ratio of p-IRE1α/IRE1α, the mRNA level of IRE1α, the expression of XBP1u, XBP1s, NLRP3, caspase-1 at both the mRNA and protein level expression of IL-1β, IL-6 and TNF-α in OGD/R injured microglia. Overexpression of IRE1 significantly reversed the effects of ICA.

DISCUSSION AND CONCLUSIONS

These results suggested that ICA might decrease the expression of IL-1β, IL-6 and TNF-α by inhibiting IRE1/XBP1s pathway. The anti-inflammatory effect of ICA may provide a potential therapeutic strategy for the treatment of brain injury after stroke.

Protective effects of tetramethylpyrazine on dysfunction of the locus coeruleus in rats exposed to single prolonged stress by anti-ER stress mechanism

Post-traumatic stress disorder (PTSD) is a serious stress-related neuropsychiatric disorder caused by major traumatic events. Abnormal activity of the locus coeruleus (LC)-noradrenergic system is related to the development of PTSD-like symptoms. Our previous studies have indicated that endoplasmic reticulum (ER) stress induced neuronal apoptosis of LC in rats with PTSD. The purpose of this study was to further investigate the role of ER stress pathways in LC neuronal dysfunction and elucidate the effect of the bioactive component tetramethylpyrazine (TMP) against ER stress response. We used an acute exposure to single prolonged stress (SPS) to model PTSD in rats. There were higher norepinephrine (NE) levels in the brain, increased tyrosine hydroxylase expression in LC, and enhanced anxiety-like behaviors in rats exposed to SPS, which were observed by enzyme-linked immunosorbent assay, western blot analysis and elevated plus maze test, respectively. In addition, the three major pathways of ER stress were activated by SPS exposure, which may be involved in the dysregulation of the LC-noradrenergic system of rats with PTSD. Furthermore, we found that TMP administration significantly suppressed the increased responsiveness of LC-noradrenergic system, effectively reduced the anxiety response of SPS rats, and selectively attenuated the activation of pro-apoptotic ER stress pathways. The results suggest that TMP was efficient in improving the LC-NE dysfunction induced by excessive ER stress. TMP exhibited a significant neuroprotective effect and potential therapeutics on PTSD-like symptoms.

Olanzapine Induces Inflammation and Immune Response via Activating ER Stress in the Rat Prefrontal Cortex

OBJECTIVE

Antipsychotics, in particular olanzapine, are first-line medications for schizophrenia. The prefrontal cortex (PFC) is an important region for antipsychotics' therapeutic effects. The PFC inflammatory and immune pathways are associated with schizophrenia pathogenesis. However, the effect of antipsychotics on the inflammatory and immune pathways in the PFC remains unclear. We aimed to examined the time-dependent effect of olanzapine on inflammatory and immune markers in the PFC of rats. Since the inflammatory and immune pathways are related to endoplasmic reticulum (ER) stress, we further investigated whether or not olanzapine-induced inflammation and immune responses were related to ER stress.

METHODS

Expression of pro-inflammatory markers including IkappaB kinase β (IKKβ), nuclear factor kappa B (NFκB), tumor necrosis factor α (TNF-α), interleukin-6 (IL-6) and IL-1β, and immune-related proteins including inducible nitric oxide synthase (iNOS), toll-like receptor 2 (TLR2) and cluster of differentiation 14 (CD14) were examined by Western blotting.

RESULTS

Olanzapine treatments for 1, 8 and 36 days significantly activated the inflammatory IKKβ/NFκB signaling, and increased the expression of TNF-α, IL-6, IL-1β and immune-related proteins such as iNOS, TLR4 and CD14. Olanzapine treatment for 1 day, 8 and 36 days also induced ER stress in the PFC. Co-treatment with an ER stress inhibitor, 4-phenylbutyrate, inhibited olanzapine-induced inflammation and the immune response in the PFC.

CONCLUSION

These results suggested olanzapine exposure could be a factor that induces central inflammation and immunological abnormities in schizophrenia subjects. Olanzapine induces PFC inflammation and immune response, possibly via activating ER stress signaling.

Longdan Xiegan Tang attenuates liver injury and hepatic insulin resistance by regulating the angiotensin-converting enzyme 2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The ancient Chinese herbal formula Longdan Xiegan Tang (LXT, also called Gentiana Longdancao Decoction to Drain the Liver) treats insulin resistance- and inflammation-associated liver injuries in clinical practice.

AIM OF THE STUDY

To investigate the molecular mechanisms underlying LXT-elicited improvement of the liver injuries.

MATERIALS AND METHODS

Male rats were co-treated with olanzapine (5 mg/kg) and LXT extract (50 and 500 mg/kg) for eight weeks. Blood parameters were determined enzymatically or by ELISA. Gene/protein expression was analyzed by Real-Time PCR, Western blot and/or immunohistochemistry.

RESULTS

LXT attenuated olanzapine-induced liver injury manifested by hyperactivities of plasma alanine aminotransferase and aspartate aminostransferase, hyperbilirubinemia and hypoalbuminemia. Furthermore, LXT improved hepatic insulin resistance that was indicated by hyperinsulinemia, the increased HOMA-IR index, and hepatic over-phosphorylation of Ser307 in insulin receptor substrate (IRS)1, Ser731 in IRS2, Tyr607 in phosphoinositide 3-kinase p85α and Ser473 in AKT at baseline. Mechanistically, LXT inhibited olanzapine-triggered hepatic over-phosphorylation of both IκB kinase (IKK)α/β and nuclear factor (NF)κB p65 proteins, and mRNA overexpression of tumor necrosis factor α, interleukin 6, interleukin 1β and CD68. More importantly, LXT restored the decreases in angiotensin-converting enzyme 2 (ACE2) protein level, and its downstream targets Ang (1-7) content and Mas receptor expression.

CONCLUSIONS

The present results demonstrate that LXT attenuates liver injury and hepatic insulin resistance by regulating the ACE2/Ang (1-7)/Mas axis-mediated anti-inflammatory pathway in rats. Our findings provide a better understanding of LXT for treatment of insulin resistance- and inflammation-associated liver injuries.

Repetitive Transcranial Magnetic Stimulation: A Potential Treatment for Obesity in Patients with Schizophrenia

Obesity is highly prevalent in patients with schizophrenia and, in association with metabolic syndrome, contributes to premature deaths of patients due to cardiovascular disease complications. Moreover, pharmacologic, and behavioral interventions have not stemmed the tide of obesity in schizophrenia. Therefore, novel effective interventions are urgently needed. Repetitive transcranial magnetic stimulation (rTMS) has shown efficacy for inducing weight loss in obese non-psychiatric samples but this promising intervention has not been evaluated as a weight loss intervention in patients with schizophrenia. In this narrative review, we describe three brain mechanisms (hypothalamic inflammation, dysregulated mesocorticolimbic reward system, and impaired prefrontal cortex function) implicated in the pathogenesis and pathophysiology of obesity and emphasize how the three mechanisms have also been implicated in the neurobiology of schizophrenia. We then argue that, based on the three overlapping brain mechanisms in obesity and schizophrenia, rTMS would be effective as a weight loss intervention in patients with schizophrenia and comorbid obesity. We end this review by describing how deep TMS, relative to conventional TMS, could potentially result in larger effect size for weight loss. While this review is mainly conceptual and based on an extrapolation of findings from non-schizophrenia samples, our aim is to stimulate research in the use of rTMS for weight loss in patients with schizophrenia.

Network pharmacology-based exploration of therapeutic mechanism of Liu-Yu-Tang in atypical antipsychotic drug-induced metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is prevalent in patients receiving atypical antipsychotic drugs (AADs), but there are few effective interventions. The Traditional Chinese herbal decoction Liu-Yu-Tang (LYT) has achieved clinical improvement for AAD-induced MetS, but its pharmacological mechanism remains unclear.

METHOD

A network pharmacology-based method was utilized in this study. First, the TCMSP and SwissTargetPrediction database were used to acquire plasma-absorbed components and putative targets of LYT, respectively. Second, an interaction network between shared targets of LYT and MetS was constructed using STRING online tool. Topological analyses were performed to extract hub gene targets. Finally, we did a pathway analysis of gene targets using the Kyoto Encyclopedia of Genes and Genomes (KEGG) to find biological pathways of LYT.

RESULTS

We obtained 655 putative targets of LYT, 434 known targets of AADs, and 1577 MetS-related gene targets. There are 232 shared targets between LYT and MetS. Interaction network construction and topological analysis yielded 60 hub targets, of which 18 were major hub targets, among which IL-6, IL-8, TNF, PI3K, MAPK, and NF-κB (RELA) are the most important in LYT's treatment of AAD-induced MetS. Pathway enrichment analysis revealed a statistically high significance of the AGE-RAGE signaling pathway in diabetic complications, lipid and atherosclerosis and the insulin resistance pathway.

CONCLUSIONS

LYT may control activities of the pro-inflammatory cytokines IL-6, IL-8, TNF and the important signal transduction molecules PI3K, MAPKs, and NF-κB (RELA), regulating metabolic disturbance-related pathways like the AGE-RAGE signaling pathway in diabetic complications, lipid and atherosclerosis, and the insulin resistance pathway, generating therapeutic effects for AAD-induced MetS.

The protein kinase D1-mediated inflammatory pathway is involved in olanzapine-induced impairment of skeletal muscle insulin signaling in rats

AIMS

Skeletal muscle insulin resistance (SMIR) contributes to the metabolic syndrome. Mounting evidence has demonstrated that the second generation antipsychotic olanzapine causes SMIR. The present study sought to investigate the molecular mechanisms underlying olanzapine-induced SMIR.

MAIN METHODS

Male rats were given olanzapine (5 mg/kg, by a gavage method) for consecutive eight weeks. Plasma glucose and insulin concentrations were determined enzymatically or by ELISA. Gene/protein expression was analyzed by Real-Time PCR, Western blot and/or immunohistochemistry.

KEY FINDINGS

Olanzapine increased fasting plasma insulin concentration, and decreased glucose clearance during insulin tolerance test in rats. In skeletal muscle, it decreased protein expression of membrane glucose transporter (GLUT) 4, the ratio of membrane to total GLUT4, and total insulin receptor substrate 1 (IRS1). However, it increased protein phosphorylation of Ser³⁰⁷ in IRS1, Y⁶⁰⁷ in phosphoinositide 3-kinase p85α and Ser³⁰⁷ in AKT. These results indicate olanzapine-induced impairment of skeletal muscle insulin signaling. Mechanistically, olanzapine upregulated mRNA expression of TNFα, IL6 and IL1β, and protein phosphorylation of both IκB kinase (IKK)α/β and nuclear factor (NF)κB p65. Furthermore, it increased protein phosphorylation of Ser^485/491 in AMPKα2, whereas it decreased AMPKα2 activity. More importantly, both Western blot and immunohistochemical analyses revealed that olanzapine increased protein phosphorylation of Ser^744/748 in protein kinase D1 (PKD1).

SIGNIFICANCE

The present results suggest that the PKD1-mediated inflammatory pathway is involved in olanzapine-induced impairment of skeletal muscle insulin signaling in rats. Our findings may go new insight into the mechanisms underlying olanzapine-induced SMIR.

Olanzapine-Induced Activation of Hypothalamic Astrocytes and Toll-Like Receptor-4 Signaling via Endoplasmic Reticulum Stress Were Related to Olanzapine-Induced Weight Gain

The antipsychotic drug olanzapine is associated with serious obesity side effects. Hypothalamic astrocytes and associated toll-like receptor-4 (TLR4) signaling play an essential role in obesity pathogenesis. This study investigated the effect of olanzapine on astrocytes and TLR4 signaling both in vitro and in the rat hypothalamus and their potential role in olanzapine-induced weight gain. We found that olanzapine treatment for 24 h dose-dependently increased cell viability, increased the protein expression of astrocyte markers including glial fibrillary acidic protein (GFAP) and S100 calcium binding protein B (S100B), and activated TLR4 signaling in vitro. In rats, 8- and 36-day olanzapine treatment caused weight gain accompanied by increased GFAP and S100B protein expression and activated TLR4 signaling in the hypothalamus. These effects still existed in pair-fed rats, suggesting that these effects were not secondary effects of olanzapine-induced hyperphagia. Moreover, treatment with an endoplasmic reticulum (ER) stress inhibitor, 4-phenylbutyrate, inhibited olanzapine-induced weight gain and ameliorated olanzapine-induced changes in hypothalamic GFAP, S100B, and TLR4 signaling. The expression of GFAP, S100B, and TLR4 correlated with food intake and weight gain. These findings suggested that olanzapine-induced increase in hypothalamic astrocytes and activation of TLR4 signaling were related to ER stress, and these effects may be related to olanzapine-induced obesity.

Peripheral mechanisms of acute olanzapine induced metabolic dysfunction: A review of in vivo models and treatment approaches

Antipsychotic (AP) medications are associated with an increased risk for developing metabolic side effects including weight gain, dyslipidemia, hypertension, type 2 diabetes (T2D), and cardiovascular disease. Previous reviews have focused on the chronic metabolic side effects associated with AP use. However, an underappreciated aspect of APs are the rapid perturbations in glucose and lipid metabolism that occur with each dose of drug. The purpose of this narrative review is to summarize work examining the peripheral mechanisms of acute olanzapine-induced related metabolic disturbances. We also discuss recent studies that have attempted to elucidate treatment approaches to mitigate AP-induced impairments in fuel metabolism.

The Unfolded Protein Response and Autophagy as Drug Targets in Neuropsychiatric Disorders

Neurons are polarized in structure with a cytoplasmic compartment extending into dendrites and a long axon that terminates at the synapse. The high level of compartmentalization imposes specific challenges for protein quality control in neurons making them vulnerable to disturbances that may lead to neurological dysfunctions including neuropsychiatric diseases. Synapse and dendrites undergo structural modulations regulated by neuronal activity involve key proteins requiring strict control of their turnover rates and degradation pathways. Recent advances in the study of the unfolded protein response (UPR) and autophagy processes have brought novel insights into the specific roles of these processes in neuronal physiology and synaptic signaling. In this review, we highlight recent data and concepts about UPR and autophagy in neuropsychiatric disorders and synaptic plasticity including a brief outline of possible therapeutic approaches to influence UPR and autophagy signaling in these diseases.

IRE1 signaling pathway mediates protective autophagic response against manganese-induced neuronal apoptosis in vivo and in vitro

Overexposure to manganese (Mn) can result in neurotoxicity and is associated with manganism, a Parkinson's-like neurological disorder. In addition, Mn can induce endoplasmic reticulum (ER) stress and autophagy. In this study, we used C57BL/6 mice to establish a model of manganism and found that Mn could induce cell injury. Our results also showed that Mn could initiate the unfolded protein response (UPR) signaling and autophagy, via initiation of the UPR signaling occurring earlier than autophagy. We further investigated the intrinsic relationship between the endoplasmic reticulum to nucleus 1(ERN1, also known as inositol requiring enzyme 1, IRE1) signaling pathway and autophagy induction in SH-SY5Y cells exposed to Mn. Our results revealed that autophagy activation was a protective response in Mn-induced toxicity. Additionally, we found that Jun N-terminal kinase (JNK) inhibition downregulated autophagy and interaction of c-Jun with the Beclin1 promoter. In addition, knockdown of IRE1 with the LV-IRE1 shRNA suppressed the expression of IRE1, TRAF2, p-ASK1, and p-JNK in Mn-treated SH-SY5Y cells. Furthermore, the expression of proteins associated with ASK1-TRAF2 complex formation and autophagy activation were reversed by the LV-IRE1 shRNA. These findings suggest that IRE1 was involved in the activation of JNK through the formation of the ASK1-TRAF2 complex, and JNK activation led to the induction of autophagy, which required Beclin1 transcription by c-Jun. In this study, we demonstrated that the IRE1 signaling pathway mediated the activation of JNK signaling via the formation of the ASK1-TRAF2 complex which could initiate autophagy and the protein c-Jun which regulates Beclin1 transcription in Mn-induced neurotoxicity.

Metabolic and endocrinal effects of N-desmethyl-olanzapine in mice with obesity: Implication for olanzapine-associated metabolic changes

Clinical use of the antipsychotic drug olanzapine (OLA) is associated with metabolic side effects to variable degrees. N-desmethyl-olanzapine (DMO) is one major metabolite of OLA, but its potential involvement in the metabolic responses remains unclear. Here we examined whether DMO can directly impact the metabolic, endocrinal and inflammatory parameters under conditions of metabolic disturbance. DMO administration (2 mg/kg, i.g.) to high-fat diet induced obesity mice for 4 weeks induced a remarkable loss of body weight and fat mass. DMO improved insulin resistance and energy expenditure in mice, but had no significant effects on dyslipidemia or hepatic steatosis. Moreover, DMO induced morphological changes in the white adipose tissue, accompanied by reduced interleukin-1β (IL-1β) production and increased UCP1 expression. These findings demonstrate that DMO is devoid of the metabolic side effects commonly observed for OLA during obesity, which suggests that the N-desmethyl metabolism may function to regulate the metabolic responses to OLA.