Brain stem as a target site for the metabolic side effects of olanzapine

GLP1 receptor agonism protects against acute olanzapine-induced hyperglycemia

Olanzapine is a second-generation antipsychotic (SGA) used in the treatment of schizophrenia and a number of off-label conditions. Although effective in reducing psychoses, acute olanzapine treatment causes hyperglycemia. Pharmacological agonists of the glucagon-like peptide 1 (GLP1) receptor have been shown to offset weight gain associated with chronic SGA administration. It is not known whether GLP1 receptor agonism would mitigate the acute metabolic side effects of SGAs. Within this context, we sought to determine whether pharmacological targeting of the GLP1 receptor would be sufficient to protect against acute olanzapine-induced impairments in glucose and lipid homeostasis. Male C57BL/6J mice were treated with olanzapine and/or the GLP1 receptor agonists liraglutide and exendin 4, and the blood glucose response was measured. We found that liraglutide or exendin 4 completely protected male mice against olanzapine-induced hyperglycemia in parallel with increases in circulating insulin (liraglutide, exendin 4) and reductions in glucagon (liraglutide only). In additional experiments, female mice, which are protected from acute olanzapine-induced hyperglycemia, displayed hyperglycemia, increases in glucagon, and reductions in insulin when treated with olanzapine and the GLP1 receptor antagonist exendin 9-39 compared with olanzapine treatment alone. Although in some instances the pharmacological targeting of the GLP1 receptor attenuated indexes of olanzapine-induced lipolysis, increases in liver triglyceride accumulation were not impacted. Our findings provide evidence that signaling through the GLP1 receptor can remarkably influence acute olanzapine-induced hyperglycemia, and from the standpoint of protecting against acute excursions in blood glucose, GLP1 receptor agonists should be considered as an adjunct treatment approach.NEW & NOTEWORTHY Antipsychotic drugs cause rapid perturbations in glucose and lipid metabolism. In the present study we have demonstrated that cotreatment with glucagon-like peptide 1 (GLP1) receptor agonists, such as liraglutide, protects against metabolic dysregulation caused by the antipsychotic drug olanzapine. These findings suggest that pharmacological targeting of the GLP1 receptor could be an effective adjunct approach to mitigate the harmful acute metabolic side effects of antipsychotic drugs.

Neuronal defects in a human cellular model of 22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11DS) is a highly penetrant and common genetic cause of neuropsychiatric disease. Here we generated induced pluripotent stem cells from 15 individuals with 22q11DS and 15 control individuals and differentiated them into three-dimensional (3D) cerebral cortical organoids. Transcriptional profiling across 100 days showed high reliability of differentiation and revealed changes in neuronal excitability-related genes. Using electrophysiology and live imaging, we identified defects in spontaneous neuronal activity and calcium signaling in both organoid- and 2D-derived cortical neurons. The calcium deficit was related to resting membrane potential changes that led to abnormal inactivation of voltage-gated calcium channels. Heterozygous loss of DGCR8 recapitulated the excitability and calcium phenotypes and its overexpression rescued these defects. Moreover, the 22q11DS calcium abnormality could also be restored by application of antipsychotics. Taken together, our study illustrates how stem cell derived models can be used to uncover and rescue cellular phenotypes associated with genetic forms of neuropsychiatric disease.

N-acetylcysteine prevents olanzapine-induced oxidative stress in mHypoA-59 hypothalamic neurons

Olanzapine is a second-generation antipsychotic (AP) drug commonly prescribed for the treatment of schizophrenia. Recently, olanzapine has been found to cause brain tissue volume loss in rodent and primate studies; however, the underlying mechanism remains unknown. Abnormal autophagy and oxidative stress have been implicated to have a role in AP-induced neurodegeneration, while N-acetylcysteine (NAC) is a potent antioxidant, shown to be beneficial in the treatment of schizophrenia. Here, we investigate the role of olanzapine and NAC on cell viability, oxidative stress, mitochondrial mass and mitophagy in hypothalamic cells. Firstly, cell viability was assessed in mHypoA-59 and mHypoA NPY/GFP cells using an MTS assay and flow cytometric analyses. Olanzapine treated mHypoA-59 cells were then assessed for mitophagy markers and oxidative stress; including quantification of lysosomes, autophagosomes, LC3B-II, p62, superoxide anion (O₂^–) and mitochondrial mass. NAC (10 mM) was used to reverse the effects of olanzapine (100 µM) on O₂⁻, mitochondrial mass and LC3B-II. We found that olanzapine significantly impacted cell viability in mHypoA-59 hypothalamic cells in a dose and time-dependent manner. Olanzapine inhibited mitophagy, instigated oxidative stress and prompted mitochondrial abnormalities. NAC was able to mitigate olanzapine-induced effects. These findings suggest that high doses of olanzapine may cause neurotoxicity of hypothalamic neurons via increased production of reactive oxygen species (ROS), mitochondrial damage and mitophagy inhibition. This could in part explain data suggesting that APs may reduce brain volume.

Universal Nature of Drug Treatment Responses in Drug-Tissue-Wide Model-Animal Experiments Using Tensor Decomposition-Based Unsupervised Feature Extraction

Gene expression profiles of tissues treated with drugs have recently been used to infer clinical outcomes. Although this method is often successful from the application point of view, gene expression altered by drugs is rarely analyzed in detail, because of the extremely large number of genes involved. Here, we applied tensor decomposition (TD)-based unsupervised feature extraction (FE) to the gene expression profiles of 24 mouse tissues treated with 15 drugs. TD-based unsupervised FE enabled identification of the common effects of 15 drugs including an interesting universal feature: these drugs affect genes in a gene-group-wide manner and were dependent on three tissue types (neuronal, muscular, and gastroenterological). For each tissue group, TD-based unsupervised FE enabled identification of a few tens to a few hundreds of genes affected by the drug treatment. These genes are distinctly expressed between drug treatments and controls as well as between tissues in individual tissue groups and other tissues. We also validated the assignment of genes to individual tissue groups using multiple enrichment analyses. We conclude that TD-based unsupervised FE is a promising method for integrated analysis of gene expression profiles from multiple tissues treated with multiple drugs in a completely unsupervised manner.

Olanzapine increases AMPK-NPY orexigenic signaling by disrupting H1R-GHSR1a interaction in the hypothalamic neurons of mice

Second generation antipsychotics, particularly olanzapine, induce severe obesity, which is associated with their antagonistic effect on the histamine H1 receptor (H1R). We have previously demonstrated that oral administration of olanzapine increases the concentration of neuropeptide Y (NPY) in the hypothalamus of rats, accompanied by hyperphagia and weight gain. However, it is unclear if the increased NPY after olanzapine administration is due to its direct effect on hypothalamic neurons and its H1R antagonistic property. In the present study, we showed that with an inverted U-shape dose-response curve, olanzapine increased NPY expression in the NPY-GFP hypothalamic neurons; however, this was not the case in the hypothalamic neurons of H1R knockout mice. Olanzapine inhibited the interaction of H1R and GHSR1a (ghrelin receptor) in the primary mouse hypothalamic neurons and NPY-GFP neurons examined by confocal fluorescence resonance energy transfer (FRET) technology. Furthermore, an H1R agonist, FMPH inhibited olanzapine activation of GHSR1a downstream signaling pAMPK and transcription factors of NPY (pFOXO1 and pCREB) in the hypothalamic NPY-GFP cell. However, an olanzapine analogue (E-Olan) with lower affinity to H1R presented negligible enhancement of pCREB within the nucleus of NPY neurons. These findings suggest that the H1R antagonist property of olanzapine inhibits the interaction of H1R and GHSR1a, activates GHSR1a downstream signaling pAMPK-FOXO1/pCREB and increases hypothalamic NPY: this could be one of the important molecular mechanisms of H1R antagonism of olanzapine-induced obesity in antipsychotic management of psychiatric disorders.

Second-Generation Antipsychotics and Dysregulation of Glucose Metabolism: Beyond Weight Gain

Second-generation antipsychotics (SGAs) are the cornerstone of treatment for schizophrenia because of their high clinical efficacy. However, SGA treatment is associated with severe metabolic alterations and body weight gain, which can increase the risk of type 2 diabetes and cardiovascular disease, and greatly accelerate mortality. Several underlying mechanisms have been proposed for antipsychotic-induced weight gain (AIWG), but some studies suggest that metabolic changes in insulin-sensitive tissues can be triggered before the onset of AIWG. In this review, we give an outlook on current research about the metabolic disturbances provoked by SGAs, with a particular focus on whole-body glucose homeostasis disturbances induced independently of AIWG, lipid dysregulation or adipose tissue disturbances. Specifically, we discuss the mechanistic insights gleamed from cellular and preclinical animal studies that have reported on the impact of SGAs on insulin signaling, endogenous glucose production, glucose uptake and insulin secretion in the liver, skeletal muscle and the endocrine pancreas. Finally, we discuss some of the genetic and epigenetic changes that might explain the different susceptibilities of SGA-treated patients to the metabolic side-effects of antipsychotics.

Risperidone administered during adolescence induced metabolic, anatomical and inflammatory/oxidative changes in adult brain: A PET and MRI study in the maternal immune stimulation animal model

Inflammation and oxidative stress (IOS) are considered key pathophysiological elements in the development of mental disorders. Recent studies demonstrated that the antipsychotic risperidone elicits an antiinflammatory effect in the brain. We administered risperidone for 2-weeks at adolescence to assess its role in preventing brain-related IOS changes in the maternal immune stimulation (MIS) model at adulthood. We also investigated the development of volumetric and neurotrophic abnormalities in areas related to the HPA-axis. Poly I:C (MIS) or saline (Sal) were injected into pregnant Wistar rats on GD15. Male offspring received risperidone or vehicle daily from PND35-PND49. We studied 4 groups (8-15 animals/group): Sal-vehicle, MIS-vehicle, Sal-risperidone and MIS-risperidone. [¹⁸F]FDG-PET and MRI studies were performed at adulthood and analyzed using SPM12 software. IOS and neurotrophic markers were measured using WB and ELISA assays in brain tissue. Risperidone elicited a protective function of schizophrenia-related IOS deficits. In particular, risperidone elicited the following effects: reduced volume in the ventricles and the pituitary gland; reduced glucose metabolism in the cerebellum, periaqueductal gray matter, and parietal cortex; higher FDG uptake in the cingulate cortex, hippocampus, thalamus, and brainstem; reduced NFκB activity and iNOS expression; and increased enzymatic activity of CAT and SOD in some brain areas. Our study suggests that some schizophrenia-related IOS changes can be prevented in the MIS model. It also stresses the need to search for novel strategies based on anti-inflammatory compounds in risk populations at early stages in order to alter the course of the disease.

A case of sinus pause induced by swallowing in the setting of olanzapine and guanfacine overdose

Olanzapine, a second-generation antipsychotic, is used in both adult and pediatric populations for schizophrenia, bipolar disorder, and depression and has been associated with autonomic dysregulation in the setting of overdose. Guanfacine is a sympatholytic drug used in the treatment of attention deficit hyperactivity disorder and has also been associated with autonomic dysfunction. We present a unique case of a 17-year-old male who overdosed on 340 mg of olanzapine and 189 mg of extended-release guanfacine with a previously unreported adverse event. Specifically, five days after ingestion, he developed a 5-8 s sinus pause every time he forcefully swallowed any beverage, suggestive of a vagal hypersensitivity reaction. The report will review the autonomic dysfunction of olanzapine and guanfacine and management of asymptomatic sinus pause in the critical care setting.

Molecular modeling studies of 1,2,4-triazine derivatives as novel h-DAAO inhibitors by 3D-QSAR, docking and dynamics simulations

Computational modeling methods were successfully applied to discover new 1,2,4-triazine compounds as potential h-DAAO inhibitors.

Lipid Processing in the Brain: A Key Regulator of Systemic Metabolism

Metabolic disorders, particularly aberrations in lipid homeostasis, such as obesity, type 2 diabetes mellitus, and hypertriglyceridemia often manifest together as the metabolic syndrome (MetS). Despite major advances in our understanding of the pathogenesis of these disorders, the prevalence of the MetS continues to rise. It is becoming increasingly apparent that intermediary metabolism within the central nervous system is a major contributor to the regulation of systemic metabolism. In particular, lipid metabolism within the brain is tightly regulated to maintain neuronal structure and function and may signal nutrient status to modulate metabolism in key peripheral tissues such as the liver. There is now a growing body of evidence to suggest that fatty acid (FA) sensing in hypothalamic neurons via accumulation of FAs or FA metabolites may signal nutritional sufficiency and may decrease hepatic glucose production, lipogenesis, and VLDL-TG secretion. In addition, recent studies have highlighted the existence of liver-related neurons that have the potential to direct such signals through parasympathetic and sympathetic nervous system activity. However, to date whether these liver-related neurons are FA sensitive remain to be determined. The findings discussed in this review underscore the importance of the autonomic nervous system in the regulation of systemic metabolism and highlight the need for further research to determine the key features of FA neurons, which may serve as novel therapeutic targets for the treatment of metabolic disorders.