The impact of quetiapine on the brain lipidome in a cuprizone-induced mouse model of schizophrenia

Impact of quetiapine on ion channels and contractile dynamics in rat ventricular myocyte

Antipsychotic drugs often lead to adverse effects, including those related to the cardiovascular system. Of these, quetiapine is known to cause significant changes in the QT interval although the underlying mechanism remains mysterious, prompting us to examine its effects on cardiac electrophysiological properties. Therefore, we investigated the effect of quetiapine on contraction, action potential (AP), and the associated membrane currents such as L-type Ca2+ and K+ using the whole-cell patch clamp method to examine its impacts on isolated rat ventricular myocytes. Our results showed that (1) quetiapine reduces cell contractility in a concentration-dependent manner and (2) leads to a significant prolongation in the duration of AP in isolated ventricular myocytes. This effect was both concentration and frequency-dependent; (3) quetiapine significantly decreased the Ca2+, transient outward K+, and steady-state K+ currents. However, only high concentration of quetiapine (100 μM) could significantly change the activation and reactivation kinetics of L-type Ca2+ channels. This study demonstrates that QT extension induced by quetiapine is mainly associated with the prolongation of AP. Moreover, quetiapine caused a significant decrease in contractile force and excitability of ventricular myocytes by suppressing Ca2+ and K+ currents.

Mucoadhesive chitosan-poly (lactic-co-glycolic acid) nanoparticles for intranasal delivery of quetiapine - Development & characterization in physiologically relevant 3D tissue models

Quetiapine hemifumarate (QF) delivery to the CNS via conventional formulations is challenging due to poor solubility and lower oral bioavailability (9 %). Similarly, many other second-generation antipsychotics, such as olanzapine, clozapine, and paliperidone, have also shown low oral bioavailability of <50 %. Hence, the present work was intended to formulate QF-loaded biodegradable PLGA-NPs with appropriate surface charge modification through poloxamer-chitosan and investigate its targeting potential on RPMI-2650 cell lines to overcome the limitations of conventional therapies. QF-loaded poloxamer-chitosan-PLGA in-situ gel (QF-PLGA-ISG) was designed using emulsification and solvent evaporation techniques. Developed QF-PLGA-ISG were subjected to evaluation for particle size, PDI, zeta potential, ex-vivo mucoadhesion, entrapment efficiency (%EE), and drug loading, which revealed 162.2 nm, 0.124, +20.5 mV, 52.4 g, 77.5 %, and 9.7 %, respectively. Additionally, QF-PLGA formulation showed >90 % release within 12 h compared to 80 % of QF-suspension, demonstrating that the surfactant with chitosan-poloxamer polymers could sustainably release medicine across the membrane. Ex-vivo hemolysis study proved that developed PLGA nanoparticles did not cause any hemolysis compared to negative control. Further, in-vitro cellular uptake and transepithelial permeation were assessed using the RPMI-2650 nasal epithelial cell line. QF-PLGA-ISG not only improved intracellular uptake but also demonstrated a 1.5-2-fold increase in QF transport across RPMI-2650 epithelial monolayer. Further studies in the EpiNasal™ 3D nasal tissue model confirmed the safety and efficacy of the developed QF-PLGA-ISG formulation with up to a 4-fold increase in transport compared to plain QF after 4 h. Additionally, histological reports demonstrated the safety of optimized formulation. Finally, favorable outcomes of IN QF-PLGA-ISG formulation could provide a novel platform for safe and effective delivery of QF in schizophrenic patients.

Oligodendrocytes Play a Critical Role in White Matter Damage of Vascular Dementia

With the deepening of population aging, the treatment of cognitive impairment and dementia is facing increasing challenges. Vascular dementia (VaD) is a cognitive dysfunction caused by brain blood flow damage and one of the most common causes of dementia after Alzheimer's disease. White matter damage in patients with chronic ischemic dementia often occurs before cognitive impairment, and its pathological changes include leukoaraiosis, myelin destruction and oligodendrocyte death. The pathophysiology of vascular dementia is complex, involving a variety of neuronal and vascular lesions. The current proposed mechanisms include calcium overload, oxidative stress, nitrative stress and inflammatory damage, which can lead to hypoxia-ischemia and demyelination. Oligodendrocytes are the only myelinating cells in the central nervous system and closely associated with VaD. In this review article, we intend to further discuss the role of oligodendrocytes in white matter and myelin injury in VaD and the development of anti-myelin injury target drugs.

A Nanoemulgel for Nose-to-Brain delivery of Quetiapine - QbD-Enabled formulation development & in-vitro characterization

Second-generation antipsychotics, quetiapine hemifumarate (QF), exhibited highly active against negative and positive signs of psychosis. However, contemporary reports have shown that long-term therapy with QF causes lethal thrombocytopenia and leukopenia. Hence, to circumvent the drawbacks of available therapies, the current work aimed to design a QF-loaded biodegradable nanoemulsion (QF-NE) with suitable surface charge modification by poloxamer-chitosan and evaluate its targeting efficiency against RPMI-2650 cell lines. QF-loaded poloxamer-chitosan in-situ gel (QF-Nanoemulgel) was formulated through the O/W emulsification aqueous titration technique and optimized using the QbD approach. Optimized QF-Nanoemulgel subjected to evaluate for globule size, PDI, zeta potential, %T, viscosity, %EE, and ex-vivo mucoadhesive strength were found to be 15.0 ± 0.3 nm, 0.05 ± 0.001, -18.3 ± 0.2 mV, 99.8 ± 0.8 %, 13.5 ± 2.1 cP, 69.0 ± 1.5 %, and 43.7 ± 1.5 g, respectively. QF-Nanoemulgel revealed sustained release and obeyed zero-order kinetics compared to QF-NE and QF-suspension. Additionally, nanoformulations treated blood samples did not cause hemolytic activity compared to drug and negative control after 10 h treatment. Further, in-vitro cytotoxicity, cellular uptake, and permeation of 12.5 and 25 μM QF-Nanoemulgel were assessed on RPMI-2650 cells and discovered nontoxic with 0.55 ± 0.02 µg and 1.1 ± 0.04 µg cellular permeation, respectively, which ensured the safety and potency of QF-Nanogel. Current research revealed the successful development of intranasal QF-Nanoemulgel as a novel dosage form for the safe and effective delivery of QF in schizophrenia patients.

Lipidomic Analysis Reveals Differences in the Extent of Remyelination in the Brain and Spinal Cord

During demyelination, lipid-rich myelin debris is released in the central nervous system (CNS) and must be phagocytosed and processed before new myelin can form. Although myelin comprises over 70% lipids, relatively little is known about how the CNS lipidome changes during demyelination and remyelination. In this study, we obtained a longitudinal lipidomic profile of the brain, spinal cord, and serum using a genetic mouse model of demyelination, known as Plp1-iCKO-Myrf. The mass spectrometry data is available at the Metabolomics Workbench, where it has been assigned Study ID ST002958. This model has distinct phases of demyelination and remyelination over the course of 24 weeks, in which loss of motor function peaks during demyelination. Using principal component analysis (PCA) and volcano plots, we have demonstrated that the brain and spinal cord have different remyelination capabilities and that this is reflected in different lipidomic profiles over time. We observed that plasmalogens (ether-linked phosphatidylserine and ether-linked phosphatidylcholine) were elevated specifically during the early stages of active demyelination. In addition, we identified lipids in the brain that were altered when mice were treated with a remyelinating drug, which may be CNS biomarkers of remyelination. The results of this study provide new insights into how the lipidome changes in response to demyelination, which will enable future studies to elucidate mechanisms of lipid regulation during demyelination and remyelination.

Low-dose lithium adjunct to quetiapine improves cognitive task performance in mice with MK801-induced long-term cognitive impairment: Evidence from a pilot study

BACKGROUND

Low-dose lithium (LD-Li) has been shown to rescue cognitive impairment in mouse models of short-term mild cognitive impairment, dementia, and schizophrenia. However, few studies have characterized the effects of LD-Li, alone or in conjunction with anti-psychotics, in the mouse model of MK801-induced long term cognitive impairment.

METHODS

The present study used in vivo Ca2+ imaging and a battery of cognitive function assessments to investigate the long-term effects of LD-Li on cognition in mice exposed to repeated injections of MK801. Prefrontal Ca2+ activity was visualized to estimate alterations in neural activity in the model mice. Pre-pulse inhibition (PPI), novel object recognition (NOR), Morris water maze (MWM), and fear conditioning (FC) tasks were used to characterize cognitive performance; open field activity (OFA) testing was used to observe psychotic symptoms. Two treatment strategies were tested: LD-Li [250 mg/d human equivalent dose (HED)] adjunct to quetiapine (QTP; 600 mg/d HED); and QTP-monotherapy (mt; 600 mg/d HED).

RESULTS

Compared to the QTP-mt group, the LD-Li + QTP group showed greatly improved cognitive performance on all measures between experimental days 29 and 85. QTP-mt improved behavioral measures compared to untreated controls, but the effects persisted only from day 29 to day 43. These data suggest that LD-Li + QTP is superior to QTP-mt for improving long-term cognitive impairments in the MK801 mouse model.

LIMITATIONS

There is no medical consensus regarding lithium use in patients with schizophrenia.

CONCLUSION

More pre-clinical and clinical studies are needed to further investigate effective treatment strategies for patients with long-term cognitive impairments, such as chronic schizophrenia.

Lipidomic analysis reveals differences in the extent of remyelination in the brain and spinal cord

During demyelination, lipid-rich myelin debris is released in the central nervous system (CNS) and must be phagocytosed and processed before new myelin can form. Although myelin comprises over 70% lipids, relatively little is known about how the CNS lipidome changes during demyelination and remyelination. In this study, we obtained a longitudinal lipidomic profile of the brain, spinal cord, and serum using a genetic mouse model of demyelination, known as Plp1 -iCKO- Myrf mice. This model has distinct phases of demyelination and remyelination over the course of 24 weeks, in which loss of motor function peaks during demyelination. Using principal component analysis (PCA) and volcano plots, we have demonstrated that the brain and spinal cord have different remyelination capabilities and that this is reflected in different lipidomic profiles over time. We observed that plasmalogens (ether-linked phosphatidylserine and ether-linked phosphatidylcholine) were elevated specifically during the early stages of active demyelination. In addition, we identified lipids in the brain that were altered when mice were treated with a remyelinating drug, which may be CNS biomarkers of remyelination. The results of this study provide new insights into how the lipidome changes in response to demyelination, which will enable future studies to elucidate mechanisms of lipid regulation during demyelination and remyelination.

Low-dose lithium mono- and adjunctive therapies improve MK-801-induced cognitive impairment and schizophrenia-like behavior in mice - Evidence from altered prefrontal lobe Ca2+ activity

BACKGROUND

Few studies have evaluated lithium either as monotherapy or in combination with anti-psychotic agents to improve cognition in murine models of schizophrenia.

METHODS

Visualization of Ca²⁺ activity in the prefrontal cortex was used to characterize brain neural activity. Novel object recognition (NOR), Morris water maze (MWM), and fear conditioning (FCT) tests were used to characterize cognitive performance; while pre-pulse inhibition (PPI), elevated plus maze (EPM) and the open field test (OFT) were used to characterize schizophrenia-like behavior.

RESULTS

A 28-day course of low-dose lithium (human equivalent dose of 250 mg/day) combined with moderate-dose quetiapine (human equivalent dose of 600 mg/day) improved Ca²⁺ ratio by 70.10 %, PPI by 69.28 %, NOR by 70.09 %, MWM by 71.28 %, FCT by 68.56 %, EPM by 70.95 % and OFT by 75.23 % compared to the results of positive controls. Unexpectedly, moderate-dose lithium (human equivalent dose of 500 mg/day) used either as monotherapy or as an adjunct with quetiapine worsened Ca²⁺ activity, PPI, MWM, FCT, EPM, and OPT.

LIMITATIONS

Our study cannot explain the contrasting positive and negative effects of low-dose and moderate-dose lithium, respectively, when used either as monotherapies or as adjuncts. Further studies, especially Western blotting, may reveal molecular mechanisms of action.

CONCLUSIONS

Low-dose lithium (human equivalent dose of 250 mg/day) combined with moderate-dose quetiapine (human equivalent dose of 600 mg/day) provided the best improvements. Furthermore, benefits persisted for 14 days post-treatment. Our data provide directions for further research of therapeutic alternatives to mitigate schizophrenia-related cognopathy.

Lipidomics reveals perturbations in the liver lipid profile of iron-overloaded mice

Iron overload is an important contributor to disease. The liver, the major site of iron storage in the body, is a key organ impacted by iron overload. While several studies have reported perturbations in liver lipids in iron overload, it is not clear, on a global scale, how individual liver lipid ions are altered. Here, we used lipidomics to study the changes in hepatic lipid ions in iron-overloaded mice. Iron overload was induced by daily intraperitoneal injections of 100 mg/kg body weight iron dextran for 1 week. Iron overload was verified by serum markers of iron status, liver iron quantitation, and Perls stain. Compared with the control group, the serum of iron-overload mice exhibited low levels of urea nitrogen and high-density lipoprotein (HDL), and high concentrations of total bile acid, low-density lipoprotein (LDL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), suggestive of liver injury. Moreover, iron overload disrupted liver morphology, induced reactive oxygen species (ROS) production, reduced superoxide dismutase (SOD) activity, caused lipid peroxidation, and led to DNA fragmentation. Iron overload altered the overall composition of lipid ions in the liver, with significant changes in over 100 unique lipid ions. Notably, iron overload selectively increased the overall abundance of glycerolipids and changed the composition of glycerophospholipids and sphingolipids. This study, one of the first to report iron-overload induced lipid alterations on a global lipidomics scale, provides early insight into lipid ions that may be involved in iron overload-induced pathology.

The Effects of Repetitive Transcranial Magnetic Stimulation on Cognitive Impairment and the Brain Lipidome in a Cuprizone-Induced Mouse Model of Demyelination

The protective effects of repetitive transcranial magnetic stimulation (rTMS) on myelin integrity have been extensively studied, and growing evidence suggests that rTMS is beneficial in improving cognitive functions and promoting myelin repair. However, the association between cognitive improvement due to rTMS and changes in brain lipids remains elusive. In this study, we used the Y-maze and 3-chamber tests, as well as a mass spectrometry-based lipidomic approach in a CPZ-induced demyelination model in mice to assess the protective effects of rTMS on cuprizone (CPZ)-induced cognitive impairment and evaluate changes in lipid composition in the hippocampus, prefrontal cortex, and striatum. We found that CPZ induced cognitive impairment and remarkable changes in brain lipids, specifically in glycerophospholipids. Moreover, the changes in lipids within the prefrontal cortex were more extensive, compared to those observed in the hippocampus and striatum. Notably, rTMS ameliorated CPZ-induced cognitive impairment and partially normalized CPZ-induced lipid changes. Taken together, our data suggest that rTMS may reverse cognitive behavioral changes caused by CPZ-induced demyelination by modulating the brain lipidome, providing new insights into the therapeutic mechanism of rTMS.

Shared Biological Pathways between Antipsychotics and Omega-3 Fatty Acids: A Key Feature for Schizophrenia Preventive Treatment?

Schizophrenia typically emerges during adolescence, with progression from an ultra-high risk state (UHR) to the first episode of psychosis (FEP) followed by a chronic phase. The detailed pathophysiology of schizophrenia and the factors leading to progression across these stages remain relatively unknown. The current treatment relies on antipsychotics, which are effective for FEP and chronic schizophrenia but ineffective for UHR patients. Antipsychotics modulate dopaminergic and glutamatergic neurotransmission, inflammation, oxidative stress, and membrane lipids pathways. Many of these biological pathways intercommunicate and play a role in schizophrenia pathophysiology. In this context, research of preventive treatment in early stages has explored the antipsychotic effects of omega-3 supplementation in UHR and FEP patients. This review summarizes the action of omega-3 in various biological systems involved in schizophrenia. Similar to antipsychotics, omega-3 supplementation reduces inflammation and oxidative stress, improves myelination, modifies the properties of cell membranes, and influences dopamine and glutamate pathways. Omega-3 supplementation also modulates one-carbon metabolism, the endocannabinoid system, and appears to present neuroprotective properties. Omega-3 has little side effects compared to antipsychotics and may be safely prescribed for UHR patients and as an add-on for FEP patients. This could to lead to more efficacious individualised treatments, thus contributing to precision medicine in psychiatry.

Enhancing cancer-associated fibroblast fatty acid catabolism within a metabolically challenging tumor microenvironment drives colon cancer peritoneal metastasis

Most cancer-related deaths result from the progressive growth of metastases. Patients with peritoneal metastatic (PM) colorectal cancer have reduced overall survival. Currently, it is still unclear why colorectal cancer (CRC) cells home to and proliferate inside the peritoneal cavity, and there is no effective consolidation therapy for improved survival. Using a proteomic approach, we found that key enzymes of fatty acid oxidation (FAO) were decreased in patients with PM colorectal cancer. Furthermore, we confirmed that carnitine palmitoyltransferase IA (CPT1A), a rate-limiting enzyme of FAO, was expressed at significantly low levels in patients with PM colorectal cancer, as determined by RT-qPCR, IHC, and GEO dataset analysis. However, lipidomics revealed no difference in FFA levels between PM and non-PM primary tumors. Here, we showed that cancer-associated fibroblasts (CAFs) promote the proliferation, migration, and invasion of colon cancer cells via upregulating CPT1A to actively oxidize FAs and conduct minimal glycolysis. In addition, coculture-induced glycolysis increased in cancer cells while fatty acid catabolism decreased with lower adiponectin levels. Importantly, inhibition of glycolysis significantly reduced the survival of CRC cells after incubation with conditioned medium from CAFs^{CPT1A -OE} in vitro and impaired the survival and growth of organoids derived from CRC-PM. Finally, we found that directly blocking FAO in CAFs^{CPT1A -OE} with etomoxir inhibits migration and invasion in vitro and decreases tumor growth and intraperitoneal dissemination in vivo, revealing a role for CAF CPT1A in promoting tumor growth and invasion. In conclusion, our results suggest the possibility of testing FAO inhibition as a novel approach and clinical strategy against CAF-induced colorectal cancer with peritoneal dissemination/metastases.