Effects of risperidone on energy balance in female C57BL/6J mice

Early adolescent second-generation antipsychotic exposure produces long-term, post-treatment increases in body weight and metabolism-associated gene expression

The use of second-generation antipsychotic (SGA) medications in pediatric patients raises concerns about potential long-term adverse outcomes. The current study evaluated the long-term effects of treatment with risperidone or olanzapine on body weight, caloric intake, serum insulin, blood glucose, and metabolism-associated gene expression in C57Bl/6J female mice. Compared to mice treated with vehicle, female mice treated with risperidone or olanzapine gained weight at higher rates during treatment and maintained higher body weights for months following treatment cessation. High-fat diet feeding did not produce a robust difference in weight gain in previously treated vs. control groups. Finally, female mice previously treated with olanzapine also exhibited increased expression of genes associated with inflammation and lipogenesis. These findings suggest that pediatric use of SGA medications that induce excess weight gain during treatment may exert persistent effects on body weight and gene expression and such outcomes may form an important aspect of assessing risk-to-benefit ratios in prescribing decisions.

IUPHAR themed review: The gut microbiome in schizophrenia

Gut microbial dysbiosis or altered gut microbial consortium, in schizophrenia suggests a pathogenic role through the gut-brain axis, influencing neuroinflammatory and neurotransmitter pathways critical to psychotic, affective, and cognitive symptoms. Paradoxically, conventional psychotropic interventions may exacerbate this dysbiosis, with antipsychotics, particularly olanzapine, demonstrating profound effects on microbial architecture through disruption of bacterial phyla ratios, diminished taxonomic diversity, and attenuated short-chain fatty acid synthesis. To address these challenges, novel therapeutic strategies targeting the gut microbiome, encompassing probiotic supplementation, prebiotic compounds, faecal microbiota transplantation, and rationalised co-pharmacotherapy, show promise in attenuating antipsychotic-induced metabolic disruptions while enhancing therapeutic efficacy. Harnessing such insights, precision medicine approaches promise to transform antipsychotic prescribing practices by identifying patients at risk of metabolic side effects based on their microbial profiles. This IUPHAR review collates the current literature landscape of the gut-brain axis and its intricate relationship with schizophrenia while advocating for integrating microbiome assessments and therapeutic management. Such a fundamental shift in proposing microbiome-informed psychotropic prescriptions to optimise therapeutic efficacy and reduce adverse metabolic impacts would align antipsychotic treatments with microbiome safety, prioritising 'gut-neutral' or gut-favourable drugs to safeguard long-term patient outcomes in schizophrenia therapy.

Vilazodone exposure during pregnancy: Effects on embryo-fetal development, pregnancy outcomes and fetal neurotoxicity by BDNF/Bax-Bcl2/5-HT mediated mechanisms

The high prevalence of major depressive disorder (MDD) among women of childbearing age necessitates careful consideration of antidepressant use during pregnancy. Although newer antidepressants, such as Vilazodone (VLZ), are preferred for their enhanced therapeutic profiles; however, their safety during pregnancy and long-term effects on offspring brains remain inadequately addressed. Therefore, this study aimed to investigate the reproductive and developmental neurotoxicity of VLZ given at equivalent therapeutic doses during gestation in a rat model. Pregnant Wistar dams were orally administered either with 1 mg/day or 2 mg/day of VLZ from gestation day (GD) 6-21. The dams were sacrificed at GD 21, and the placentas and fetuses were collected. Fetal brains were then subjected to neurohistopathological, neurochemical, and biochemical analysis. Prenatal exposure to VLZ at 2 mg/day resulted in significant maternal, reproductive, and embryo-fetal toxicity, characterized by reduced food intake, diminished weight gain in pregnant dams, and smaller litter sizes, along with decreased fetal and placental weights. These effects were associated with developmental neurotoxicity, which manifested as decreased fetal brain size and weight, a substantial reduction in neocortical layer thickness, brain-derived neurotrophic factor (BDNF) expression, serotonin, dopamine, and norepinephrine neurotransmitter levels (5-HT, DA, and NE), and increased apoptotic activity (Bax and Bcl-2 ratio) and acetylcholinesterase levels in the developing brain. Our findings indicate that prenatal VLZ exposure interfere with crucial brain development processes involving the BDNF/Bax-Bcl2/5-HT signalling pathways, leading to long-lasting neurodevelopmental impairments. This study is the first to document the adverse effects of VLZ on fetal brain development, highlighting the need for further research to assess the safety of VLZ use during pregnancy.

Deciphering Risperidone-Induced Lipogenesis by Network Pharmacology and Molecular Validation

BACKGROUND

Risperidone is an atypical antipsychotic that can cause substantial weight gain. The pharmacological targets and molecular mechanisms related to risperidone-induced lipogenesis (RIL) remain to be elucidated. Therefore, network pharmacology and further experimental validation were undertaken to explore the action mechanisms of RIL.

METHODS

RILs were systematically analyzed by integrating multiple databases through integrated network pharmacology, transcriptomics, molecular docking, and molecular experiment analysis. The potential signaling pathways for RIL were identified and experimentally validated using gene ontology (GO) enrichment and Kyoto encyclopedia of genes and genomes (KEGG) analysis.

RESULTS

Risperidone promotes adipocyte differentiation and lipid accumulation through Oil Red O staining and reverse transcription-polymerase chain reaction (RT-PCR). After network pharmacology and GO analysis, risperidone was found to influence cellular metabolism. In addition, risperidone influences adipocyte metabolism, differentiation, and lipid accumulation-related functions through transcriptome analysis. Intersecting analysis, molecular docking, and pathway validation analysis showed that risperidone influences the adipocytokine signaling pathway by targeting MAPK14 (mitogen-activated protein kinase 14), MAPK8 (mitogen-activated protein kinase 8), and RXRA (retinoic acid receptor RXR-alpha), thereby inhibiting long-chain fatty acid β-oxidation by decreasing STAT3 (signal transducer and activator of transcription 3) expression and phosphorylation.

CONCLUSION

Risperidone increases adipocyte lipid accumulation by plausibly inhibiting long-chain fatty acid β-oxidation through targeting MAPK14 and MAPK8.

The atypical antipsychotic risperidone targets hypothalamic melanocortin 4 receptors to cause weight gain

Atypical antipsychotics such as risperidone cause drug-induced metabolic syndrome. However, the underlying mechanisms remain largely unknown. Here, we report a new mouse model that reliably reproduces risperidone-induced weight gain, adiposity, and glucose intolerance. We found that risperidone treatment acutely altered energy balance in C57BL/6 mice and that hyperphagia accounted for most of the weight gain. Transcriptomic analyses in the hypothalamus of risperidone-fed mice revealed that risperidone treatment reduced the expression of Mc4r. Furthermore, Mc4r in Sim1 neurons was necessary for risperidone-induced hyperphagia and weight gain. Moreover, we found that the same pathway underlies the obesogenic effect of olanzapine-another commonly prescribed antipsychotic drug. Remarkably, whole-cell patch-clamp recording demonstrated that risperidone acutely inhibited the activity of hypothalamic Mc4r neurons via the opening of a postsynaptic potassium conductance. Finally, we showed that treatment with setmelanotide, an MC4R-specific agonist, mitigated hyperphagia and obesity in both risperidone- and olanzapine-fed mice.

Altered gut bacterial-fungal interkingdom networks in patients with current depressive episode

INTRODUCTION

Bacterial dysbiosis has been described in patients with current depressive episode (CDE); however, the fungal composition in the gut has not been investigated in these patients.

METHODS

Here, we characterized the fungal gut mycobiota in patients with CDE. We systematically characterized the microbiota and mycobiota in fecal samples obtained from 24 patients with CDE and 16 healthy controls (HC) using 16S rRNA gene- and ITS1-based DNA sequencing, respectively.

RESULTS

In patients with CDE, bacterial dysbiosis was characterized by an altered composition and reduced correlation network density, and the gut mycobiota was characterized by a relative reduction in alpha diversity and altered composition. Most notably, the CDE group had higher levels of Candida and lower level of Penicillium than the HC group. Compared with the HC group, the gut microbiota in patients with CDE displayed a significant disruption in the bacteria-fungi correlation network suggestive of altered interkingdom interactions. Furthermore, a gut microbial index based on the combination of eight genera (four bacterial and four fungal CDE-associated genera) distinguished CDE patients from controls with an area under the curve of approximately 0.84, suggesting that the gut microbiome signature is a promising tool for disease classification.

CONCLUSIONS

Our findings suggest that both bacteria and fungi contribute to gut dysbiosis in patients with CDE. Future studies involving larger cohorts and metagenomic or metabolomic analyses may clarify the structure and potential roles and functions of the gut mycobiome and its impact on the development of CDE.

Exploring mechanisms of increased cardiovascular disease risk with antipsychotic medications: Risperidone alters the cardiac proteomic signature in mice

Atypical antipsychotic (AA) medications including risperidone (RIS) and olanzapine (OLAN) are FDA approved for the treatment of psychiatric disorders including schizophrenia, bipolar disorder and depression. Clinical side effects of AA medications include obesity, insulin resistance, dyslipidemia, hypertension and increased cardiovascular disease risk. Despite the known pharmacology of these AA medications, the mechanisms contributing to adverse metabolic side-effects are not well understood. To evaluate drug-associated effects on the heart, we assessed changes in the cardiac proteomic signature in mice administered for 4 weeks with clinically relevant exposure of RIS or OLAN. Using proteomic and gene enrichment analysis, we identified differentially expressed (DE) proteins in both RIS- and OLAN-treated mouse hearts (p < 0.05), including proteins comprising mitochondrial respiratory complex I and pathways involved in mitochondrial function and oxidative phosphorylation. A subset of DE proteins identified were further validated by both western blotting and quantitative real-time PCR. Histological evaluation of hearts indicated that AA-associated aberrant cardiac gene expression occurs prior to the onset of gross pathomorphological changes. Additionally, RIS treatment altered cardiac mitochondrial oxygen consumption and whole body energy expenditure. Our study provides insight into the mechanisms underlying increased patient risk for adverse cardiac outcomes with chronic treatment of AA medications.

Functional Changes of Orexinergic Reaction to Psychoactive Substances

It is becoming increasingly apparent the importance of the central nervous system (CNS) as the major contributor to the regulation of systemic metabolism. Antipsychotic drugs are used often to treat several psychiatric disorders, including schizophrenia and bipolar disorder However, antipsychotic drugs prescription, particularly the second-generation ones (SGAs), such as clozapine and olanzapine, is related to a considerable weight gain which usually leads to obesity. The aim of this paper is to assess the influence of orexin A on sympathetic and hyperthermic reactions to several neuroleptic drugs. Orexin A is a neuropeptide which effects both body temperature and food intake by increasing sympathetic activity. Orexin A-mediated hyperthermia is reduced by haloperidol and is blocked by clozapine and olanzapine. Orexin A-mediated body temperature elevation is increased by risperidone. These hyperthermic effects are delayed by quietapine. In this paper, it is discussed the orexinergic pathway activation by neuroleptic drugs and its influence on human therapeutic strategies. With the aim to determine that neuroleptic drugs mediate body temperature control through to the orexinergic system, we summarized our previously published data. Psychiatric disorders increase the risk of developing metabolic disorders (e.g., weight gain, increased blood pressure, and glucose or lipid levels). Therefore, the choice of antipsychotic drug to be prescribed, based on the relevant risks and benefits of each individual drug, has an essential role in human health prevention.

Risperidone-induced weight gain is mediated through shifts in the gut microbiome and suppression of energy expenditure

Risperidone is a second-generation antipsychotic that causes weight gain. We hypothesized that risperidone-induced shifts in the gut microbiome are mechanistically involved in its metabolic consequences. Wild-type female C57BL/6J mice treated with risperidone (80 μg/day) exhibited significant excess weight gain, due to reduced energy expenditure, which correlated with an altered gut microbiome. Fecal transplant from risperidone-treated mice caused a 16% reduction in total resting metabolic rate in naïve recipients, attributable to suppression of non-aerobic metabolism. Risperidone inhibited growth of cultured fecal bacteria grown anaerobically more than those grown aerobically. Finally, transplant of the fecal phage fraction from risperidone-treated mice was sufficient to cause excess weight gain in naïve recipients, again through reduced energy expenditure. Collectively, these data highlight a major role for the gut microbiome in weight gain following chronic use of risperidone, and specifically implicates the modulation of non-aerobic resting metabolism in this mechanism.

Propranolol Attenuates Risperidone-Induced Trabecular Bone Loss in Female Mice

Atypical antipsychotic (AA) drugs cause significant metabolic side effects, and clinical data are emerging that demonstrate increased fracture risk and bone loss after treatment with the AA, risperidone (RIS). The pharmacology underlying the adverse effects on bone is unknown. However, RIS action in the central nervous system could be responsible because the sympathetic nervous system (SNS) is known to uncouple bone remodeling. RIS treatment in mice significantly lowered trabecular bone volume fraction (bone volume/total volume), owing to increased osteoclast-mediated erosion and reduced osteoblast-mediated bone formation. Daytime energy expenditure was also increased and was temporally associated with the plasma concentration of RIS. Even a single dose of RIS transiently elevated expression of brown adipose tissue markers of SNS activity and thermogenesis, Pgc1a and Ucp1. Rankl, an osteoclast recruitment factor regulated by the SNS, was also increased 1 hour after a single dose of RIS. Thus, we inferred that bone loss from RIS was regulated, at least in part, by the SNS. To test this, we administered RIS or vehicle to mice that were also receiving the nonselective β-blocker propranolol. Strikingly, RIS did not cause any changes in trabecular bone volume/total volume, erosion, or formation while propranolol was present. Furthermore, β2-adrenergic receptor null (Adrb2(-/-)) mice were also protected from RIS-induced bone loss. This is the first report to demonstrate SNS-mediated bone loss from any AA. Because AA medications are widely prescribed, especially to young adults, clinical studies are needed to assess whether β-blockers will prevent bone loss in this vulnerable population.

Effect of Asenapine on the Activity of Hypocretin Neurons in Normal and Unpredictable Mild Stress Preconditioned Rats

Asenapine (ASE) is a novel atypical antipsychotic used in schizophrenia treatment. Here, the effect of ASE on Fos expression in hypocretin (Hcrt) neurons in medial and lateral portions of the lateral hypothalamus (LH) and the effect of chronic unpredictable variable mild stress (CMS) preconditioning were studied. CMS consisted of restraint, social isolation, crowding, swimming, and cold and lasted 21 days. The rats were sacrificed on day 22, 90 min after a single injection of vehicle (saline 300 μl/rat subcutaneously--s.c.) or ASE (0.3 mg/kg s.c.). Control (CON), ASE, CMS, and CMS+ASE groups were used. Fos protein was visualized by the avidin biotin peroxidase technique, while Hcrt perikarya by fluorescent dye. Fos/Hcrt co-localizations were evaluated under parallel light and fluorescent illuminations. In the single Fos expression assessment, the Fos number was significantly higher in the medial in comparison with the lateral LH portion in each group. No differences in Fos amount were observed between the individual groups within the medial and lateral LH portions. In the Fos/Hcrt co-localization assessments, ASE significantly reduced the number of Fos/Hcrt neurons in the medial, but not lateral, LH portion in ASE and CMS+ASE groups. CMS only slightly contributed to the inhibitory effect of ASE in the CMS+ASE groups. The present data show as the first that ASE may reduce the activity of Hcrt cells in the medial LH portion, which might correspond with the relatively low weight gain liability of ASE. CMS preconditioning did not significantly interfere with this impact of ASE.

Carnitine Palmitoyltransferase 1b Deficiency Protects Mice from Diet-Induced Insulin Resistance

BACKGROUND

Carnitine Palmitoyl Transferase 1 (CPT1) is the rate-limiting enzyme governing long-chain fatty acid entry into mitochondria. CPT1 inhibitors have been developed and exhibited beneficial effects against type II diabetes in short-term preclinical animal studies. However, the long-term effects of treatment remain unclear and potential non-specific effects of these CPT1 inhibitors hamper in-depth understanding of the potential molecular mechanisms involved.

METHODS

We investigated the effects of restricting the activity of the muscle isoform CPT1b in mice using heterozygous CPT1b deficient (Cpt1b+/-) and Wild Type (WT) mice fed with a High Fat Diet (HFD) for 22 weeks. Insulin sensitivity was assessed using Glucose Tolerance Test (GTT), insulin tolerance test and hyperinsulinemic euglycemic clamps. We also examined body weight/composition, tissue and systemic metabolism/energetic status, lipid profile, transcript analysis, and changes in insulin signaling pathways.

RESULTS

We found that Cpt1b+/- mice were protected from HFD-induced insulin resistance compared to WT littermates. Cpt1b+/- mice exhibited elevated whole body glucose disposal rate and skeletal muscle glucose uptake. Furthermore, Cpt1b+/- skeletal muscle showed diminished ex vivo palmitate oxidative capacity by ~40% and augmented glucose oxidation capacity by ~50% without overt change in whole body energy metabolism. HFD feeding Cpt1b+/- but not WT mice exhibited well-maintained insulin signaling in skeletal muscle, heart, and liver.

CONCLUSION

The present study on a genetic model of CPT1b restriction supports the concept that partial CPT1b inhibition is a potential therapeutic strategy.