Immunolocalization of peroxisome proliferator-activated receptors and retinoid x receptors in the adult rat CNS

Baicalin alleviates sepsis-associated acute kidney injury through activation of the PPAR-γ/UCP1 signaling pathway

PURPOSE

This study aims to investigate the protective effect of baicalin on sepsis-associated acute kidney injury (SA-AKI) and its molecular mechanism.

MATERIALS AND METHODS

An SA-AKI mouse model was established via lipopolysaccharide (LPS) injection. Baicalin's effects on renal function, oxidative stress, and apoptosis were evaluated using histopathology, dihydroethidium, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Bioinformatics, molecular docking, ribonucleic acid (RNA) sequencing, and Western blotting were employed to investigate the role of baicalin in regulating the peroxisome proliferator‑activated receptor‑γ (PPAR-γ)/uncoupling protein 1 (UCP1) pathway. Human kidney-2 cells were used for in vitro validation.

RESULTS

In this study, baicalin significantly ameliorated LPS-induced acute kidney injury by modulating the PPAR-γ/UCP1 signaling pathway. Both in vivo and in vitro experiments revealed that baicalin attenuates inflammation, oxidative stress, and apoptosis while restoring mitochondrial function. RNA sequencing analysis revealed significant upregulation of PPAR-γ/UCP1 in the baicalin-treated group. Further molecular docking and molecular dynamics simulations confirmed a stable interaction between baicalin and UCP1. Validation via small interfering RNA-mediated knockdown of PPAR-γ and UCP1 revealed that inhibition of the PPAR-γ/UCP1 pathway abrogated baicalin's protective effects, highlighting the critical role of this pathway in mediating baicalin's renoprotection.

CONCLUSION

Baicalin protects against SA-AKI by activating the PPAR-γ/UCP1 signaling pathway. This study provides new insights into the mechanisms through which baicalin mitigates kidney injury in sepsis, suggesting its potential as a therapeutic agent for SA-AKI.

The endocannabinoid and paracannabinoid systems in natural reward processes: possible pharmacological targets?

Natural rewards such as food, mating, and social interaction are essential for survival and species preservation, and their regulation involves a complex interplay of motivational, cognitive, and emotional processes. Over the past two decades, increasing attention has been directed toward the endocannabinoid system and its paracannabinoid counterpart as key modulators of these behaviors. This review aims to provide an integrated overview of the roles played by the endocannabinoid and paracannabinoid systems in regulating natural reward-driven behaviors, focusing on feeding, reproductive behavior, and social interaction. We highlight how the endocannabinoid system - mainly through CB1 receptor signaling - modulates central and peripheral circuits involved in energy homeostasis, reward processing, and emotional regulation. In parallel, we explore the role of paracannabinoids, such as oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and stearoylethanolamide (SEA), which act primarily via non-cannabinoid receptors and contribute to the regulation of appetite, sexual motivation, and social behavior. Special attention is given to the relevance of these systems in the pathophysiology of obesity, eating disorders, sexual dysfunctions, and social impairments, as well as their potential as pharmacological targets. Overall, the evidence discussed supports a broader conceptualization of endocannabinoid and paracannabinoid signaling as pivotal regulators of natural rewards and opens new avenues for the development of targeted interventions for motivational and reward-related disorders.

Potentials of peroxisome proliferator-activated receptor (PPAR) α, β/δ, and γ: An in-depth and comprehensive review of their molecular mechanisms, cellular Signalling, immune responses and therapeutic implications in multiple diseases

Peroxisome proliferator-activated receptors (PPARs), ligand-activated transcription factors, have emerged as a key regulator of various biological processes, underscoring their relevance in the pathophysiology and treatment of numerous diseases. PPARs are primarily recognized for their critical role in lipid and glucose metabolism, which underpins their therapeutic applications in managing type 2 diabetes mellitus. Beyond metabolic disorders, they have gained attention for their involvement in immune modulation, making them potential targets for autoimmune-related inflammatory diseases. Furthermore, PPAR's ability to regulate proliferation, differentiation, and apoptosis has positioned them as promising candidates in oncology. Their anti-inflammatory and anti-fibrotic properties further highlight their potential in dermatological and cardiovascular conditions, where dysregulated inflammatory responses contribute to disease progression. Recent advancements have elucidated the molecular mechanisms of different PPAR isoforms, including their regulation of key signalling pathways such as NF-κB and MAPK, which are crucial in inflammation and cellular stress responses. Additionally, their interactions with co-factors and post-translational modifications further diversify their functional roles. The therapeutic potential of various PPAR agonists has been extensively explored, although challenges related to side effects and target specificity remain. This growing body of evidence underscores the significance of PPARs in understanding the molecular basis of diseases and advancing therapeutic interventions, paving way for targeted treatment approach across a wide spectrum of medical conditions. Here, we provide a comprehensive and detailed perspective of PPARs and their potential across different health conditions to advance our understanding, elucidate underlying mechanisms, and facilitate the development of potential treatment strategies.

Nuclear receptor PPARγ targets GPNMB to promote oligodendrocyte development and remyelination

Myelin injury occurs in brain ageing and in several neurological diseases. Failure of spontaneous remyelination is attributable to insufficient differentiation of oligodendrocyte precursor cells (OPCs) into mature myelin-forming oligodendrocytes in CNS demyelinated lesions. Emerging evidence suggests that peroxisome proliferator-activated receptor γ (PPARγ) is the master gatekeeper of CNS injury and repair and plays an important regulatory role in various neurodegenerative diseases. Although studies demonstrate positive effects of PPARγ in oligodendrocyte ontogeny in vitro, the cell-intrinsic role of PPARγ and the molecular mechanisms involved in the processes of OPC development and CNS remyelination in vivo are poorly understood. Here, we identify PPARγ as an enriched transcription factor in the dysfunctional OPCs accumulated in CNS demyelinated lesions. Its expression increases during OPC differentiation and myelination and is closely related to the process of CNS demyelination/remyelination. Administration of pharmacological agonists of PPARγ not only promotes OPC differentiation and CNS myelination, but also causes a significant increase in remyelination in both cuprizone- and lysophosphatidylcholine-induced demyelination models. In contrast, the attenuation of PPARγ function, either through the specific knockout of PPARγ in oligodendrocytes in vivo or through its inhibition in vitro, leads to decreased OPC maturation, hindered myelin generation and reduced therapeutic efficacy of PPARγ agonists. At a mechanistic level, PPARγ induces myelin repair by directly targeting glycoprotein non-metastatic melanoma protein B (GPNMB), a novel regulator that drives OPCs to differentiate into oligodendrocytes, promotes myelinogenesis in the developing CNS of postnatal mice and enhances remyelination in mice with lysophosphatidylcholine-induced demyelination. In conclusion, our evidence reveals that PPARγ is a positive regulator of endogenous OPC differentiation and CNS myelination/remyelination and suggests that PPARγ and/or its downstream sensor (GPNMB) might be a candidate pharmacological target for regenerative therapy in the CNS.

Fatty acid binding proteins and their involvement in anxiety and mood disorders

Anxiety and mood disorders represent the most prevalent neuropsychiatric conditions. Nevertheless, current pharmacotherapies often have a host of adverse side effects. Emerging evidence suggests modulation of lipid signaling pathways - particularly those involved in the endocannabinoid (eCB) system, may offer promising new targets for the treatment of anxiety and depression. Polyunsaturated fatty acids (PUFA) and their metabolic derivatives, including the eCB ligands, have garnered significant attention for their roles in neuropsychiatric disease mechanisms. Intracellular transportation of these lipids is facilitated by fatty acid binding proteins (FABP), which are increasingly recognized as key regulators of lipid signaling. Accumulating evidence indicates that FABPs may impact the development of neuropsychiatric disorders by mediating the signaling pathways of PUFAs and eCB ligands. In this review, we investigate the role of FABPs in two major categories of neuropsychiatric conditions - anxiety disorders and clinical depression. We begin by examining several neuropathophysiological mechanisms through which FABPs can impact these conditions, focusing on their role as lipid chaperones. These mechanisms include the trafficking of eCB ligands, as well as oleoylethanolamide and palmitoylethanolamide; modulation of inflammatory responses through PUFA transport and PPAR activation; regulation of PUFA availability to support neurogenesis; influence on stress-related pathways, including NMDA receptor activation and the hypothalamic-pituitary-adrenal axis; and the facilitation of dopamine receptor trafficking and localization. Next, we discuss preclinical evidence linking FABP function to anxiety- and depression-related behaviours. Finally, we propose that pharmacologically targeting FABP-mediated pathways holds considerable potential as a novel therapeutic strategy for addressing the symptoms associated with mood and anxiety disorders.

Quantitative 3D histochemistry reveals region-specific amyloid-β reduction by the antidiabetic drug netoglitazone

A hallmark of Alzheimer's disease (AD) is the extracellular aggregation of toxic amyloid-beta (Aβ) peptides in form of plaques. Here, we identify netoglitazone, an antidiabetic compound previously tested in humans, as an Aβ aggregation antagonist. Netoglitazone improved cognition and reduced microglia activity in a mouse model of AD. Using quantitative whole-brain three-dimensional histology (Q3D), we precisely identified brain regions where netoglitazone reduced the number and size of Aβ plaques. We demonstrate the utility of Q3D in preclinical drug evaluation for AD by providing a high-resolution brain-wide view of drug efficacy. Applying Q3D has the potential to improve pre-clinical drug evaluation by providing information that can help identify mechanisms leading to brain region-specific drug efficacy.

Repurposing Antidiabetic Drugs for Cerebrovascular Diseases: Causal Evidence from Drug Target Mendelian Randomization and Colocalization

Cerebrovascular diseases have caused substantial social and economic burdens, and new treatment methods are urgently needed. Evaluating the feasibility of the use of antidiabetic drugs for treating cerebrovascular diseases is meaningful in this field. We designed a comprehensive study process that includes two-sample Mendelian randomization (MR), which uses genetic proxies for antidiabetic drug targets, summary-based MR (SMR) for mRNAs, and colocalization for drug target genes to assess their causal relationships with 10 cerebrovascular disease phenotypes. Seven of the eight main types of clinical antidiabetic drugs were identified, yielding eleven potential drug targets. Our study observed that sulfonylureas (KCNJ11) and metformin (GPD1) reduce the risk of stroke and that TZDs (PPARG) reduce the risk of hippocampal perivascular spaces. In addition, sulfonylureas can reduce the risk of certain cerebral small vessel disease. These results show that antidiabetic drugs have hypoglycemic properties and affect cerebrovascular health. Our study supports repurposing antidiabetic drugs as disease-modifying therapies to improve cerebrovascular health. Future research should focus on studying the role of drugs in different phenotypes of cerebrovascular diseases and explore the potential molecular mechanisms to analyze further the potential effects of antidiabetic drugs on cerebrovascular diseases.

Gut microbiome and serum metabolites in neuropathic pain: The PPARα perspective

Neuropathic pain (NP) is a chronic disease state centred on neuroinflammation with a high prevalence and limited effective treatment options. Peroxisome proliferator-activated receptor α (PPARα) has emerged as a promising target for NP management due to its anti-inflammatory properties. Recent evidence highlights the critical role of the gut microbiome and its metabolites in NP pathogenesis. This study aimed to investigate whether PPARα modulates the development and alleviation of NP by influencing gut microbial communities and serum metabolites. 16S rDNA sequencing and liquid chromatography-mass spectrometry (LC-MS/MS) untargeted metabolomics analyses performed 14 days after the establishment of a chronic constriction injury (CCI) pain model in C57BL/6 J mice showed significant changes in gut microbial and metabolite levels in CCI mice. Intraperitoneal injection of the PPARα agonist GW7647 (5 mg/kg) significantly attenuated mechanical allodynia and thermal hyperalgesia in CCI mice, whereas injection of the PPARα antagonist GW6471 (20 mg/kg) produced the opposite effect. Immunofluorescence analysis revealed that GW7647 effectively suppressed microglial activation. Additionally, PPARα agonist and antagonist treatments markedly altered the composition and abundance of intestinal microbial communities in CCI mice. Further serum LC-MS/MS analysis identified 258 potential serum metabolic biomarkers, many of which correlated with changes in gut microbial composition. These findings demonstrate that PPARα influences serum metabolite profiles by modulating gut microbiota composition, which subsequently affects NP progression. This study provides novel insights into the mechanisms underlying NP and suggests potential therapeutic avenues targeting PPARα and gut microbiota.

Ketamine impairs the performance of male mice in novel recognition object test and reduces the immunoreactivity of GAD67 in the hippocampus: Role of pioglitazone

Schizophrenia is a mental disorder characterized by positive, negative, and cognitive symptoms which is treated with antipsychotics. However, these drugs present several side effects and, some schizophrenia symptoms, like cognitive, are difficult to treat. The peroxisome proliferator-activated receptors-gamma (PPAR-γ) are expressed in dopaminergic neurons of the midbrain participating in the modulation of dopamine-mediated behavior . We investigated the effects of pioglitazone, an agonist of PPAR-γ, on the behavioral alterations induced by ketamine and, whether alterations in monoamine oxidase (MAO) activity, glutamic acid decarboxylase (GAD67), PPAR-γ or tyrosine hydroxylase (TH) immunoreactivity in brain tissues are involved in these effects. Male mice received ketamine (30 mg/kg), intraperitoneally, for 14 consecutive days, and pioglitazone (3 or 9 mg/kg), by gavage (day 8 up to day 14). Ketamine decreased nail-biting increasing the time exploring the center of the open field on day 8 and the number of rearing evaluated 30 min after its administration on day 14. Furthermore, ketamine decreased the percentage of investigation in the NOR test and the immunoreactivity of GAD67 in the hippocampus. No significant changes were found in other behavioral and biochemical tests. Pioglitazone attenuated the effects of ketamine on rearing and GAD67 immunoreactivity in the hippocampus, recovering the ketamine effects on NOR test. At a dose of 9 mg/kg, pioglitazone alone reduced the immunoreactivity of GAD67 in the hippocampus. Pioglitazone at both doses recovered the cognitive symptoms induced by ketamine an effect that seems to involve the modulation of GAD67 immunoreactivity in the hippocampus. In conclusion, pioglitazone improved the effects of ketamine on the NOR test which was, at least in part, associated with the modulation of GAD67 immunoreactivity in the hippocampus suggesting its beneficial role in cognitive symptoms.

Neuroglia in substance use disorders

Substance use disorders (SUD) remain a major public health concern in which individuals are unable to control their use of substances despite significant harm and negative consequences. Drugs of abuse dysregulate major brain and behavioral functions. Glial cells, primarily microglia and astrocytes, play a crucial role in these drug-induced molecular and behavioral changes. This review explores preclinical and clinical studies of how neuroglia and their associated neuroinflammatory responses contribute to SUD and reward-related properties. We evaluate preclinical and clinical evidence for targeting neuroglia as therapeutic interventions. In addition, we evaluate the literature on the gut microbiome and its role in SUD. Clinical treatments are most effective for reducing drug cravings, and some have yielded promising results in other measures of drug use. N-Acetylcysteine, through modulation of cysteine-glutamate antiporter of glial cells, shows encouraging results across a variety of drug classes. Neuroglia and gut microbiome interactions are important factors to consider with regard to SUD and could lead to novel therapeutic avenues. Age- and sex-dependent properties of neuroglia, gut microbiome, and drug use behaviors are important areas in need of further investigation.

The phytohormone abscisic acid enhances remyelination in mouse models of multiple sclerosis

Introduction

Over the past few decades, there has been a sudden rise in the incidence of Multiple Sclerosis (MS) in Western countries. However, current treatments often show limited efficacy in certain patients and are associated with adverse effects, which highlights the need for safer and more effective therapeutic approaches. Environmental factors, particularly dietary habits, have been observed to play a substantial role in the development of MS. In this study, we are the first to investigate the potential protective effect of the phytohormone abscisic acid (ABA) in MS. ABA, which is abundant in fruits such as figs, apricots and bilberries, is known to cross the blood-brain barrier and has demonstrated neuroprotective effects in conditions like depression and Alzheimer's disease.

Methods

In this study, we investigated whether ABA supplementation enhances remyelination in both ex vivo and in vivo mouse models.

Results

Our results indicated that ABA enhanced remyelination and that this enhanced remyelination is associated with increased lipid droplet load, reduced levels of degraded myelin, and a higher abundance of F4/80+ cells in the demyelinated brain of mice treated with ABA. In in vitro models, we further demonstrated that ABA treatment elevates lipid droplet formation by enhancing the phagocytic capacity of macrophages. Additionally, in a mouse model of microglial activation, we showed that ABA-treated mice maintain a less inflammatory microglial phenotype.

Conclusion

Our findings highlight a crucial role for macrophages and microglia in enabling ABA to enhance the remyelination process. Furthermore, ABA's ability to improve remyelination together with its ability to reduce microglial activation, make ABA a promising candidate for modulating macrophage phenotype and reducing neuroinflammation in MS.

Saroglitazar, a PPAR α/γ agonist alleviates 3-Nitropropionic acid induced neurotoxicity in rats: Unveiling the underlying mechanisms

Saroglitazar (SGZ), a peroxisomal proliferated activated receptor α/γ agonist showed neuroprotective effects in various neurodegenerative disorders like Alzheimer's and Parkinson's. However, no studies were performed on Huntington's, so the goal of the current study is to examine the effect of SGZ on Huntington's disease like symptoms induced by 3-Nitropropionic acid. In this protocol, twenty-four rats were divided into four groups, each group consisting of 6 animals. Group 1: The control group received 1 % CMC 10 mg/kg, p.o. for 14 days. Groups 2, 3, and 4 received 3-NP 15 mg/kg, i.p. from Day 1 to Day 7. Groups 3 and 4 received SGZ 5 mg/kg, p.o. and 10 mg/kg, p.o. respectively once daily from day 1 to day 14. Various behavioral tests like OFT, rotarod, hanging wire, narrow beam walk, MWM, and Y-maze were performed. On day-15, the animals were euthanised by cervical dislocation and brain sample were isolated for biochemical and histopathological analysis. Administration of 3-NP showed a significant decrease in motor coordination and cognitive function. Furthermore, 3-NP altered the activity of acetylcholinesterase, anti-oxidant enzymes, Nrf-2, NF-κB, BDNF, CREB levels, and histological features. However, treatment with SGZ showed ameliorative effects in the 3-NP induced neurotoxicity via PPAR α/γ pathway by reducing motor dysfunction, memory impairment, cholinesterase levels, oxidative stress, neuroinflammation. It also enhanced the levels of Nrf-2, BDNF, and CREB expression and improved histological features. In conclusion, treatment with Saroglitazar attenuated Huntington's disease-like symptoms in rats which are induced by 3-NP via activation of PPAR α/γ pathway.

Pioglitazone attenuates behavioral and electrophysiological dysfunctions induced by two-hit model of schizophrenia in adult rodent offspring

Maternal infection and stress exposure, especially during childhood and adolescence, have been implicated as risk factors for schizophrenia. Both insults induce an exacerbated inflammatory response, which could mediate disturbance of neurodevelopmental processes and, ultimately, malfunctioning of neural systems observed in this disorder. Thus, anti-inflammatory drugs, such as PPARγ agonists, may potentially be used to prevent the development of schizophrenia. Microglia culture was prepared from the offspring of saline or poly(I:C)-injected mice. The cells were pretreated with pioglitazone and then, stimulated by LPS. Proinflammatory mediators and phagocytic activity were measured. Also, pregnant rats were injected with saline or poly(I:C) on GD17. The offspring were subjected to footshock during adolescence and subsequently injected with pioglitazone or vehicle. At adulthood, behavior and dopaminergic activity were evaluated. Pioglitazone reduced proinflammatory mediators induced by poly(I:C) microglia stimulated by LPS without affecting their decreased phagocytic activity. The PPARγ agonist also prevented the emergence of social and cognitive impairments, as well as attenuated the increased number of spontaneously active dopamine neurons in the VTA, observed in both males and females from poly(I:C) and stress group. Therefore, pioglitazone could potentially prevent the emergence of the schizophrenia-like alterations induced by the two-hit model via reduction of microglial activation.

Molecular mechanisms underlying methotrexate-induced intestinal injury and protective strategies

Methotrexate (MTX) is a folic acid reductase inhibitor that manages various malignancies as well as immune-mediated inflammatory chronic diseases. Despite being frequently prescribed, MTX's severe multiple toxicities can occasionally limit its therapeutic potential. Intestinal toxicity is a severe adverse effect associated with the administration of MTX, and patients are significantly burdened by MTX-provoked intestinal mucositis. However, the mechanism of such intestinal toxicity is not entirely understood, mechanistic studies demonstrated oxidative stress and inflammatory reactions as key factors that lead to the development of MTX-induced intestinal injury. Besides, MTX causes intestinal cells to express pro-inflammatory cytokines like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which activate nuclear factor-kappa B (NF-κB). This is followed by the activation of the Janus kinase/signal transducer and activator of the transcription3 (JAK/STAT3) signaling pathway. Moreover, because of its dual anti-inflammatory and antioxidative properties, nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) has been considered a critical signaling pathway that counteracts oxidative stress in MTX-induced intestinal injury. Several agents have potential protective effects in counteracting MTX-provoked intestinal injury such as omega-3 polyunsaturated fatty acids, taurine, umbelliferone, vinpocetine, perindopril, rutin, hesperidin, lycopene, quercetin, apocynin, lactobacillus, berberine, zinc, and nifuroxazide. This review aims to summarize the potential redox molecular mechanisms of MTX-induced intestinal injury and how they can be alleviated. In conclusion, studying these molecular pathways might open the way for early alleviation of the intestinal damage and the development of various agent plans to attenuate MTX-mediated intestinal injury.

Potential Neuroprotective Effect of the Endocannabinoid System on Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by alterations in motor capacity resulting from a decrease in the neurotransmitter dopamine due to the selective death of dopaminergic neurons of the nigrostriatal pathway. Unfortunately, conventional pharmacological treatments fail to halt disease progression; therefore, new therapeutic strategies are needed, and currently, some are being investigated. The endocannabinoid system (ECS), highly expressed in the basal ganglia (BG) circuit, undergoes alterations in response to dopaminergic depletion, potentially contributing to motor symptoms and the etiopathogenesis of PD. Substantial evidence supports the neuroprotective role of the ECS through various mechanisms, including anti-inflammatory, antioxidative, and antiapoptotic effects. Therefore, the ECS emerges as a promising target for PD treatment. This review provides a comprehensive summary of current clinical and preclinical evidence concerning ECS alterations in PD, along with potential pharmacological targets that may exert the protection of dopaminergic neurons.

Antidiabetic drugs in Parkinson's disease

This review explores the intricate connections between type 2 diabetes (T2D) and Parkinson's disease (PD), both prevalent chronic conditions that primarily affect the aging population. These diseases share common early biochemical pathways that contribute to tissue damage. This manuscript also systematically compiles potential shared cellular mechanisms between T2D and PD and discusses the literature on the utilization of antidiabetic drugs as potential therapeutic options for PD. This review encompasses studies investigating the experimental and clinical efficacy of antidiabetic drugs in the treatment of Parkinson's disease, along with the proposed mechanisms of action. The exploration of the benefits of antidiabetic drugs in PD presents a promising avenue for the treatment of this neurodegenerative disorder.

Metabolic, neurotoxic and immunotoxic effects of PFAAs and their mixtures on the proteome of the head kidney and plasma from rainbow trout (Oncorhynchus mykiss)

PFAAs (Perfluoroalkyl acids) are a class of bioaccumulative, persistent and ubiquitous environmental contaminants which primarily occupy the hydrosphere and its sediments. Currently, a paucity of toxicological information exists for short chain PFAAs and complex mixtures. In order to address these knowledge gaps, we performed a 3-week, aqueous exposure of rainbow trout to 3 different concentrations of a PFAA mixture (50, 100 and 500 ng/L) modeled after the composition determined in Lake Ontario. We conducted an additional set of exposures to individual PFAAs (25 nM each of PFOS (12,500 ng/L), PFOA (10,300 ng/L), PFBS (7500 ng/L) or PFBA (5300 ng/L) to evaluate differences in biological response across PFAA congeners. Untargeted proteomics and phosphorylated metabolomics were conducted on the blood plasma and head kidney tissue to evaluate biological response. Plasma proteomic responses to the mixtures revealed several unexpected outcomes including Similar proteomic profiles and biological processes as the PFOS exposure regime while being orders of magnitude lower in concentration and an atypical dose response in terms of the number of significantly altered proteins (FDR < 0.1). Biological pathway analysis revealed the low mixture, medium mixture and PFOS to significantly alter (FDR < 0.05) a number of processes including those involved in lipid metabolism, oxidative stress and the nervous system. We implicate plasma increases in PPARD and PPARG as being directly related to these biological processes as they are known to be important regulators in all 3 processes. In contrast to the blood plasma, the high mixture and PFOA exposure regimes caused the greatest change to the head kidney proteome, altering many proteins being involved in lipid metabolism, oxidative stress and inflammation. Our findings support the pleiotropic effect PFAAs have on aquatic organisms at environmentally relevant doses including those on PPAR signaling, metabolic dysregulation, immunotoxicity and neurotoxicity.

Electroacupuncture attenuates cerebral ischemia/reperfusion injury by regulating oxidative stress, neuronal death and neuroinflammation via stimulation of PPAR-γ

BACKGROUND

Oxidative stress and inflammatory responses play essential roles in cerebral ischemia/reperfusion (I/R) injury. Electroacupuncture (EA) is widely used as a rehabilitation method for stroke in China; however, the underlying mechanism of action remains unclear. Peroxisome proliferator-activated receptor gamma (PPAR-γ) has been reported to impact anti-inflammatory and anti-oxidative effects.

OBJECTIVE

This study investigated the role of PPAR-γ in EA-mediated effects and aimed to illuminate its possible mechanisms in cerebral I/R.

METHODS

In this study, male Sprague-Dawley (SD) rats with middle cerebral artery occlusion/reperfusion (MCAO/R) injury were treated with EA at LI11 and ST36 for 30 min daily after MCAO/R for seven consecutive days. The neuroprotective effects of EA were measured by neurobehavioral evaluation, triphenyltetrazolium chloride staining, hematoxylin-eosin staining and transmission electron microscopy. Oxidative stress, inflammatory factors, neural apoptosis and microglial activation were examined by enzyme-linked immunosorbent assay, immunofluorescence and reverse transcriptase polymerase chain reaction. Western blotting was used to assess PPAR-γ-mediated signaling.

RESULTS

We found that EA significantly alleviated cerebral I/R-induced infarct volume, decreased neurological scores and inhibited I/R-induced oxidative stress, inflammatory responses and microglial activation. EA also increased PPAR-γ protein expression. Furthermore, the protective effects of EA were reversed by injection of the PPAR-γ antagonist T0070907.

CONCLUSION

EA attenuates cerebral I/R injury by regulating oxidative stress, neuronal death and neuroinflammation via stimulation of PPAR-γ.

The promising roles of medicinal plants and bioactive compounds on hepatic lipid metabolism in the treatment of non-alcoholic fatty liver disease in animal models: molecular targets

Imbalance in hepatic lipid metabolism can lead to an abnormal triglycerides deposition in the hepatocytes which can cause non-alcoholic fatty liver disease (NAFLD). Four main mechanisms responsible for regulating hepatic lipid metabolism are fatty acid uptake, de novo lipogenesis, lipolysis and fatty acid oxidation. Controlling the expression of transcription factors at molecular level plays a crucial role in NAFLD management. This paper reviews various medicinal plants and their bioactive compounds emphasising mechanisms involved in hepatic lipid metabolism, other important NAFLD pathological features, and their promising roles in managing NAFLD through regulating key transcription factors. Although there are many medicinal plants popularly investigated for NAFLD treatment, there is still little information and scientific evidence available and there has been no research on clinical trials scrutinised on this matter. This review also aims to provide molecular information of medicinal plants in NALFD treatment that might have potentials for future scientifically controlled studies.

The effects of prolonged stress exposure on the brain of rats and insights to understand the impact of work-related stress on caregivers

Introduction

Stress exposure is a significant concern in the healthcare sector. This animal model study aims to reproduce caregivers' working conditions and determine their impact on the brain.

Method

Twenty-four healthy male rats of the Wistar strain were divided into four groups. Three groups were submitted each to one stressor for 21 days, while the fourth group was used as a control. Stressors were food and water deprivation (FW), permanent illumination (PI), and forced swimming (FS). At the end of the experiment, rats were euthanized, and stress biomarkers, biological parameters, and DNA damage were measured.

Results

Prooxidant biomarker rates increased in the different groups (+50 to +75%) compared to the control (p < 0.0001). Urinary corticosterone rates increased in all stressed animals, mainly in the PI group, with changes of up to +50% compared to the control group. Acetylcholinesterase levels decreased to -50% (p < 0.0001 for the three exposed groups). Total ATPase, (Na+/K+)-ATPase, and Mg2+-ATPase activities decreased in all stressed groups. The percentage of brain cell congestion and apoptosis was 3% for the FW group (p < 0.0001), 2% for the PI group (p < 0.0001), and 4% for the FS group (p < 0.0001) compared to the control (0.8%). DNA damage was observed in all exposed groups. Finally, we noticed behavioral changes and a depression-like syndrome in all stressed rats.

Conclusion

Stressful conditions such as the working environment of caregivers can trigger several pathophysiological processes leading to oxidative, neurochemical, and hypothalamic-pituitary-adrenal disorders. These changes can progress to cell damage and apoptosis in the brain and trigger psychological and physical disorders.

Inflammatory signaling pathways in the treatment of Alzheimer's disease with inhibitors, natural products and metabolites (Review)

The intricate nature of Alzheimer's disease (AD) pathogenesis poses a persistent obstacle to drug development. In recent times, neuroinflammation has emerged as a crucial pathogenic mechanism of AD, and the targeting of inflammation has become a viable approach for the prevention and management of AD. The present study conducted a comprehensive review of the literature between October 2012 and October 2022, identifying a total of 96 references, encompassing 91 distinct pharmaceuticals that have been investigated for their potential impact on AD by inhibiting neuroinflammation. Research has shown that pharmaceuticals have the potential to ameliorate AD by reducing neuroinflammation mainly through regulating inflammatory signaling pathways such as NF‑κB, MAPK, NLRP3, PPARs, STAT3, CREB, PI3K/Akt, Nrf2 and their respective signaling pathways. Among them, tanshinone IIA has been extensively studied for its anti‑inflammatory effects, which have shown significant pharmacological properties and can be applied clinically. Thus, it may hold promise as an effective drug for the treatment of AD. The present review elucidated the inflammatory signaling pathways of pharmaceuticals that have been investigated for their therapeutic efficacy in AD and elucidates their underlying mechanisms. This underscores the auspicious potential of pharmaceuticals in ameliorating AD by impeding neuroinflammation.

New insights into the molecular basis of alcohol abstinence and relapse in alcohol-associated liver disease

Alcohol use disorder remains a significant public health concern, affecting around 5% of adults worldwide. Novel pathways of damage have been described during the last years, providing insight into the mechanism of injury due to alcohol misuse beyond the direct effect of ethanol byproducts on the liver parenchyma and neurobehavioral mechanisms. Thus, the gut-liver-brain axis and immune system involvement could be therapeutic targets for alcohol use disorder. In particular, changes in gut microbiota composition and function, and bile acid homeostasis, have been shown with alcohol consumption and cessation. Alcohol can also directly disrupt intestinal and blood-brain barriers. Activation of the immune system can be triggered by intestinal barrier dysfunction and translocation of bacteria, pathogen-associated molecular patterns (such as lipopolysaccharide), cytokines, and damage-associated molecular patterns. These factors, in turn, promote liver and brain inflammation and the progression of liver fibrosis. Other involved mechanisms include oxidative stress, apoptosis, autophagy, and the release of extracellular vesicles and miRNA from hepatocytes. Potential therapeutic targets include gut microbiota (probiotics and fecal microbiota transplantation), neuroinflammatory pathways, as well as neuroendocrine pathways, for example, the ghrelin system (ghrelin receptor blockade), incretin mimetics (glucagon-like peptide-1 analogs), and the mineralocorticoid receptor system (spironolactone). In addition, support with psychological and behavioral treatments is essential to address the multiple dimensions of alcohol use disorder. In the future, a personalized approach considering these novel targets can contribute to significantly decreasing the alcohol-associated burden of disease.

PPARα and PPARγ are expressed in midbrain dopamine neurons and modulate dopamine- and cannabinoid-mediated behavior in mice

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors that regulate gene expression. Δ9-tetrahydrocannabinol (Δ9-THC) is a PPARγ agonist and some endocannabinoids are natural activators of PPARα and PPARγ. However, little is known regarding their cellular distributions in the brain and functional roles in cannabinoid action. Here, we first used RNAscope in situ hybridization and immunohistochemistry assays to examine the cellular distributions of PPARα and PPARγ expression in the mouse brain. We found that PPARα and PPARγ are expressed in ~70% of midbrain dopamine (DA) neurons. In the amygdala, PPARα is expressed in ~60% of glutamatergic neurons, while PPARγ is expressed in ~60%  of GABA neurons. However, no PPARα/γ signal was detected in GABA neurons in the nucleus accumbens. We then used a series of behavioral assays to determine the functional roles of PPARα/γ in the CNS effects of Δ9-THC. We found that optogenetic stimulation of midbrain DA neurons was rewarding as assessed by optical intracranial self-stimulation (oICSS) in DAT-cre mice. Δ9-THC and a PPARγ (but not PPARα) agonist dose-dependently inhibited oICSS. Pretreatment with PPARα or PPARγ antagonists attenuated the Δ9-THC-induced reduction in oICSS and Δ9-THC-induced anxiogenic effects. In addition, a PPARγ agonist increased, while PPARα or PPARγ antagonists decreased open-field locomotion. Pretreatment with PPARα or PPARγ antagonists potentiated Δ9-THC-induced hypoactivity and catalepsy but failed to alter Δ9-THC-induced analgesia, hypothermia and immobility. These findings provide the first anatomical and functional evidence supporting an important role of PPARα/γ in DA-dependent behavior and cannabinoid action.

In silico identification of microRNAs targeting the PPARα/γ: promising therapeutics for SARS-CoV‑2 infection

The SARS-CoV-2 lifecycle is dependent on the host metabolism machinery. It upregulates the PPARα and PPARγ genes in lipid metabolism, which supports the essential viral replication complex including lipid rafts and palmitoylation of viral protein. The use of PPAR ligands in SARS-CoV-2 infection may have positive effects by preventing cytokine storm and the ensuing inflammatory cascade. The inhibition of PPARα and PPARγ genes may alter the metabolism and may disrupt the lifecycle of SARS-CoV-2 and COVID-19 progression. In the present work, we have identified possible miRNAs targeting PPARα and PPARγ in search of modulators of PPARα and PPARγ genes expression. The identified miRNAs could possibly be viewed as new therapeutic targets against COVID-19 infection.

The Ameliorative Effect of Pioglitazone against Neuroinflammation Caused by Doxorubicin in Rats

Doxorubicin (DOX) is a chemotherapeutic agent that is linked with complications such as cardiotoxicity and cognitive dysfunction, known as chemobrain. Chemobrain affects up to 75% of cancer survivors, and there are no known therapeutic options for its treatment. This study aimed to determine the protective effect of pioglitazone (PIO) against DOX-induced cognitive impairment. Forty Wistar female rats were equally divided into four groups: control, DOX-treated, PIO-treated, and DOX + PIO-treated. DOX was administered at a dose of 5 mg/kg, i.p., twice a week for two weeks (cumulative dose, 20 mg/kg). PIO was dissolved in drinking water at a concentration of 2 mg/kg in the PIO and DOX-PIO groups. The survival rates, change in body weight, and behavioral assessment were performed using Y-maze, novel object recognition (NOR), and elevated plus maze (EPM), followed by estimation of neuroinflammatory cytokines IL-6, IL-1β, and TNF-α in brain homogenate and RT-PCR of a brain sample. Our results showed a survival rate of 40% and 65% in the DOX and DOX + PIO groups, respectively, compared with a 100% survival rate in the control and PIO treatment groups at the end of day 14. There was an insignificant increase in body weight in the PIO group and a significant reduction in the DOX and DOX + PIO groups as compared with the control groups. DOX-treated animals exhibited impairment of cognitive function, and the combination PIO showed reversal of DOX-induced cognitive impairment. This was evidenced by changes in IL-1β, TNF-α, and IL-6 levels and also by mRNA expression of TNF- α, and IL-6. In conclusion, PIO treatment produced a reversal of DOX-induced memory impairment by alleviating neuronal inflammation by modulating the expression of inflammatory cytokines.

High glucose inhibits neural differentiation by excessive autophagy <em>via</em> peroxisome proliferator-activated receptor gamma

The high prevalence of prediabetes and diabetes globally has led to the widespread occurrence of severe complications, such as diabetic neuropathy, which is a result of chronic hyperglycemia. Studies have demonstrated that maternal diabetes can lead to neural tube defects by suppressing neurogenesis during neuroepithelium development. While aberrant autophagy has been associated with abnormal neuronal differentiation, the mechanism by which high glucose suppresses neural differentiation in stem cells remains unclear. Therefore, we developed a neuronal cell differentiation model of retinoic acid induced P19 cells to investigate the impact of high glucose on neuronal differentiation in vitro. Our findings indicate that high glucose (HG) hinders neuronal differentiation and triggers excessive. Furthermore, HG treatment significantly reduces the expression of markers for neurons (Tuj1) and glia (GFAP), while enhancing autophagic activity mediated by peroxisome proliferator-activated receptor gamma (PPARγ). By manipulating PPARγ activity through pharmacological approaches and genetically knocking it down using shRNA, we discovered that altering PPARγ activity affects the differentiation of neural stem cells exposed to HG. Our study reveals that PPARγ acts as a downstream mediator in high glucose-suppressed neural stem cell differentiation and that refining autophagic activity via PPARγ at an appropriate level could improve neuronal differentiation efficiency. Our data provide novel insights and potential therapeutic targets for the clinical management of gestational diabetes mellitus.

Development of PPARγ Agonists for the Treatment of Neuroinflammatory and Neurodegenerative Diseases: Leriglitazone as a Promising Candidate

Increasing evidence suggests that the peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily, plays an important role in physiological processes in the central nervous system (CNS) and is involved in cellular metabolism and repair. Cellular damage caused by acute brain injury and long-term neurodegenerative disorders is associated with alterations of these metabolic processes leading to mitochondrial dysfunction, oxidative stress, and neuroinflammation. PPARγ agonists have demonstrated the potential to be effective treatments for CNS diseases in preclinical models, but to date, most drugs have failed to show efficacy in clinical trials of neurodegenerative diseases including amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. The most likely explanation for this lack of efficacy is the insufficient brain exposure of these PPARγ agonists. Leriglitazone is a novel, blood-brain barrier (BBB)-penetrant PPARγ agonist that is being developed to treat CNS diseases. Here, we review the main roles of PPARγ in physiology and pathophysiology in the CNS, describe the mechanism of action of PPARγ agonists, and discuss the evidence supporting the use of leriglitazone to treat CNS diseases.

Therapeutic modulation of JAK-STAT, mTOR, and PPAR-γ signaling in neurological dysfunctions

The cytokine-activated Janus kinase (JAK)-signal transducer and activator of transcription (STAT) cascade is a pleiotropic pathway that involves receptor subunit multimerization. The mammalian target of rapamycin (mTOR) is a ubiquitously expressed serine-threonine kinase that perceives and integrates a variety of intracellular and environmental stimuli to regulate essential activities such as cell development and metabolism. Peroxisome proliferator-activated receptor-gamma (PPARγ) is a prototypical metabolic nuclear receptor involved in neural differentiation and axon polarity. The JAK-STAT, mTOR, and PPARγ signaling pathways serve as a highly conserved signaling hub that coordinates neuronal activity and brain development. Additionally, overactivation of JAK/STAT, mTOR, and inhibition of PPARγ signaling have been linked to various neurocomplications, including neuroinflammation, apoptosis, and oxidative stress. Emerging research suggests that even minor disruptions in these cellular and molecular processes can have significant consequences manifested as neurological and neuropsychiatric diseases. Of interest, target modulators have been proven to alleviate neuronal complications associated with acute and chronic neurological deficits. This research-based review explores the therapeutic role of JAK-STAT, mTOR, and PPARγ signaling modulators in preventing neuronal dysfunctions in preclinical and clinical investigations.

Brain nuclear receptors and cardiovascular function

Brain-heart interaction has raised up increasing attentions. Nuclear receptors (NRs) are abundantly expressed in the brain, and emerging evidence indicates that a number of these brain NRs regulate multiple aspects of cardiovascular diseases (CVDs), including hypertension, heart failure, atherosclerosis, etc. In this review, we will elaborate recent findings that have established the physiological relevance of brain NRs in the context of cardiovascular function. In addition, we will discuss the currently available evidence regarding the distinct neuronal populations that respond to brain NRs in the cardiovascular control. These findings suggest connections between cardiac control and brain dynamics through NR signaling, which may lead to novel tools for the treatment of pathological changes in the CVDs.

PPARα agonist fenofibrate prevents postoperative cognitive dysfunction by enhancing fatty acid oxidation in mice

Background

Due to high rates of incidence and disability, postoperative cognitive dysfunction (POCD) currently receives a lot of clinical attention. Disturbance of fatty acid oxidation is a potential pathophysiological manifestation underlying POCD. Peroxisome proliferator-activated receptor α (PPARα) is a significant transcription factor of fatty acid oxidation that facilitates the transfer of fatty acids into the mitochondria for oxidation. The potential role of PPARα intervention in POCD warrants consideration.

Objective

The present study is aimed to investigate whether PPARα agonist fenofibrate (FF) could protect long-term isoflurane anesthesia-induced POCD model and to explore the potential underlying function of fatty acid oxidation in the process.

Methods

We established the POCD model via 6 h long-term isoflurane anesthesia in vivo with C57BL/6J mice and in vitro with N2a cells. Cells and mice were pretreated with PPARα agonist FF before anesthesia, after which fatty acid oxidation and cognitive function were assessed. The level of fatty acid oxidation-related proteins was determined using western blotting. The contextual fear conditioning test was utilized to evaluate mice's learning and memory.

Results

Our results showed that 6 h long-term isoflurane anesthesia induced contextual memory damage in mice, accompanied by decreases of fatty acid oxidation-related proteins (peroxisome proliferator-activated receptor γ coactivator 1α, carnitine palmitoyltransferase 1A, and PPARα) both in the hippocampus of POCD mice and in N2a cells. In the N2a cell model, pretreatment of PPARα agonist FF led to the upregulation of fatty acid oxidation-related proteins. In vivo results showed that preconditioned FF reached similar effects. More crucially, FF has been shown to reduce cognitive damage in mice after long-term isoflurane anesthesia. Additionally, our data showed that after blocking fatty acid oxidation by Etomoxir, FF failed to protect cognitive function from long-term isoflurane anesthesia.

Conclusions

Pretreatment of PPARα agonist FF can protect against long-term isoflurane anesthesia-induced POCD by enhancing fatty acid oxidation.

The Strategy of Targeting Peroxisome Proliferator-Activated Receptor (PPAR) in the Treatment of Neuropsychiatric Disorders

Peroxisome proliferator-activated receptors (PPARs) are nonsteroid nuclear receptors and transcription factors that regulate several neuroinflammatory and metabolic processes, recently involved in several neuropsychiatric conditions, including Alzheimer's disease, Parkinson's disease, major depressive disorder, post-traumatic stress disorder (PTSD), schizophrenia spectrum disorders, and autism spectrum disorders. PPARs are ligand-activated receptors that, following stimulation, induce neuroprotective effects by decreasing neuroinflammatory processes through inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) expression and consequent suppression of pro-inflammatory cytokine production. PPARs heterodimerize with the retinoid X-receptor (RXR) and bind to PPAR-responsive regulatory elements (PPRE) in the promoter region of target genes involved in lipid metabolism, synthesis of cholesterol, catabolism of amino acids, and inflammation. Interestingly, PPARs are considered functionally part of the extended endocannabinoid (eCB) system that includes the classic eCB, anandamide, which act at cannabinoid receptor types 1 (CB1) and 2 (CB2) and are implicated in the pathophysiology of stress-related neuropsychiatric disorders. In preclinical studies, PPAR stimulation improves anxiety and depression-like behaviors by enhancing neurosteroid biosynthesis. The peculiar functional role of PPARs by exerting anti-inflammatory and neuroprotective effects and their expression localization in neurons and glial cells of corticolimbic circuits make them particularly interesting as novel therapeutic targets for several neuropsychiatric disorders characterized by underlying neuroinflammatory/neurodegenerative mechanisms. Herein, we discuss the pathological hallmarks of neuropsychiatric conditions associated with neuroinflammation, as well as the pivotal role of PPARs with a special emphasis on the subtype alpha (PPAR-α) as a suitable molecular target for therapeutic interventions.

Effects of Prenatal Cannabinoids Exposure upon Placenta and Development of Respiratory Neural Circuits

Cannabis use has risen dangerously during pregnancy in the face of incipient therapeutic use and a growing perception of safety. The main psychoactive compound of the Cannabis sativa plant is the phytocannabinoid delta-9-tetrahydrocannabinol (A-9 THC), and its status as a teratogen is controversial. THC and its endogenous analogues, anandamide (AEA) and 2-AG, exert their actions through specific receptors (eCBr) that activate intracellular signaling pathways. CB1r and CB2r, also called classic cannabinoid receptors, together with their endogenous ligands and the enzymes that synthesize and degrade them, constitute the endocannabinoid system. This system is distributed ubiquitously in various central and peripheral tissues. Although the endocannabinoid system's most studied role is controlling the release of neurotransmitters in the central nervous system, the study of long-term exposure to cannabinoids on fetal development is not well known and is vital for understanding environmental or pathological embryo-fetal or postnatal conditions. Prenatal exposure to cannabinoids in animal models has induced changes in placental and embryo-fetal organs. Particularly, cannabinoids could influence both neural and nonneural tissues and induce embryo-fetal pathological conditions in critical processes such as neural respiratory control. This review aims at the acute and chronic effects of prenatal exposure to cannabinoids on placental function and the embryo-fetal neurodevelopment of the respiratory pattern. The information provided here will serve as a theoretical framework to critically evaluate the teratogen effects of the consumption of cannabis during pregnancy.

Endocannabinoid-Binding Receptors as Drug Targets

Cannabis plant has been used from ancient times with therapeutic purposes for treating human pathologies, but the identification of the cellular and molecular mechanisms underlying the therapeutic properties of the phytocannabinoids, the active compounds in this plant, occurred in the last years of the past century. In the late 1980s and early 1990s, seminal studies demonstrated the existence of cannabinoid receptors and other elements of the so-called endocannabinoid system. These G protein-coupled receptors (GPCRs) are a key element in the functions assigned to endocannabinoids and appear to serve as promising pharmacological targets. They include CB₁, CB₂, and GPR55, but also non-GPCRs can be activated by endocannabinoids, like ionotropic receptor TRPV₁ and even nuclear receptors of the PPAR family. Their activation, inhibition, or simply modulation have been associated with numerous physiological effects at both central and peripheral levels, which may have therapeutic value in different human pathologies, then providing a solid experimental explanation for both the ancient medicinal uses of Cannabis plant and the recent advances in the development of cannabinoid-based specific therapies. This chapter will review the scientific knowledge generated in the last years around the research on the different endocannabinoid-binding receptors and their signaling mechanisms. Our intention is that this knowledge may help readers to understand the relevance of these receptors in health and disease conditions, as well as it may serve as the theoretical basis for the different experimental protocols to investigate these receptors and their signaling mechanisms that will be described in the following chapters.

Effects of a Novel Beta Lactam Compound, MC-100093, on the Expression of Glutamate Transporters/Receptors and Ethanol Drinking Behavior of Alcohol-Preferring Rats

Chronic ethanol exposure affects the glutamatergic system in several brain reward regions including the nucleus accumbens (NAc). Our laboratory has shown that chronic exposure to ethanol reduced the expression of glutamate transporter 1 (GLT-1) and cystine/glutamate exchanger (xCT) and, as a result, increased extracellular glutamate concentrations in the NAc of alcohol-preferring (P) rats. Moreover, previous studies from our laboratory reported that chronic ethanol intake altered the expression of certain metabotropic glutamate receptors in the brain. In addition to central effects, chronic ethanol consumption induced liver injury, which is associated with steatohepatitis. In the present study, we investigated the effects of chronic ethanol consumption in the brain and liver. Male P rats had access to a free choice of ethanol and water bottles for five weeks. Chronic ethanol consumption reduced GLT-1 and xCT expression in the NAc shell but not in the NAc core. Furthermore, chronic ethanol consumption increased fat droplet content as well as peroxisome proliferator-activated receptor alpha (PPAR-α) and GLT-1 expression in the liver. Importantly, treatment with the novel beta-lactam compound, MC-100093, reduced ethanol drinking behavior and normalized the levels of GLT-1 and xCT expression in the NAc shell as well as normalized GLT-1 and PPAR-α expression in the liver. In addition, MC-100093 attenuated ethanol-induced increases in fat droplet content in the liver. These findings suggest that MC-100093 may be a potential lead compound to attenuate ethanol-induced dysfunction in the glutamatergic system and liver injury. SIGNIFICANCE STATEMENT: This study identified a novel beta-lactam, MC-100093, that has demonstrated upregulatory effects on GLT-1. MC-100093 reduced ethanol drinking behavior and normalized levels of GLT-1 and xCT expression in the NAc shell as well as normalized GLT-1 and PPAR-α expression in the liver. In addition, MC-100093 attenuated ethanol-induced increases in fat droplet content in the liver.

The Small Molecule PPARγ Agonist GL516 Induces Feeding-Stimulatory Effects in Hypothalamus Cells Hypo-E22 and Isolated Hypothalami

PPARγ agonists are implicated in the regulation of diabetes and metabolic syndrome and have therapeutic potential in brain disorders. PPARγ modulates appetite through its central effects, especially on the hypothalamic arcuate nucleus (ARC). Previous studies demonstrated that the small molecule GL516 is a PPARγ agonist able to reduce oxidative stress and apoptosis with a potential neuroprotective role. Herein, we investigated the effects of GL516, in vitro and ex vivo, on the levels of hypothalamic dopamine (DA) and serotonin (5-HT). The gene expressions of neuropeptide Y, CART, AgRP, and POMC, which play master roles in the neuroendocrine regulation of feeding behavior and energy balance, were also evaluated. HypoE22 cells were treated with H₂O₂ (300 μM) for 2 h e 30’ and with different concentrations of GL516 (1 nM-100 µM). The cell viability was evaluated after 24 and 48 h of culturing using the MTT test. DA and 5-HT levels in the HypoE22 cell supernatants were analyzed through HPLC; an ex vivo study on isolated hypothalamic specimens challenged with scalar concentrations of GL516 (1–100 µM) and with pioglitazone (10 µM) was carried out. The gene expressions of CART, NPY, AgRP, and POMC were also determined by a quantitative real-time PCR. The results obtained showed that GL516 was able to reduce DA and 5-HT turnover; moreover, it was effective in stimulating NPY and AgRP gene expressions with a concomitant reduction in CART and POMC gene expressions. These results highlight the capability of GL516 to modulate neuropeptide pathways deeply involved in appetite control suggesting an orexigenic effect. These findings emphasize the potential use of GL516 as a promising candidate for therapeutical applications in neurodegenerative diseases associated with the reduction in food intake and stimulation of catabolic pathways.

Peroxisomal Proliferator-Activated Receptor β/δ Deficiency Induces Cognitive Alterations

Peroxisome proliferator-activated receptor β/δ (PPARβ/δ), the most PPAR abundant isotype in the central nervous system, is involved in microglial homeostasis and metabolism, whose disturbances have been demonstrated to play a key role in memory impairment. Although PPARβ/δ function is well-established in metabolism, its contribution to neuronal and specifically memory process is underexplored. Therefore, the aim of the study is to determine the role of PPARβ/δ in the neuropathological pathways involved in memory impairment and as to whether a risk factor implicated in memory loss such as obesity modulates neuropathological markers. To carry out this study, 6-month-old total knock-out for the Ppard gene male mice with C57BL/6X129/SV background (PPARβ/δ-/-) and wild-type (WT) littermates with the same genetic background were used. Animals were fed, after the weaning (at 21 days old), and throughout their growth, either conventional chow (CT) or a palmitic acid-enriched diet (HFD). Thus, four groups were defined: WT CT, WT HFD, PPARβ/δ-/- CT, and PPARβ/δ-/- HFD. Before sacrifice, novel object recognition test (NORT) and glucose and insulin tolerance tests were performed. After that, animals were sacrificed by intracardiac perfusion or cervical dislocation. Different techniques, such as GolgiStain kit or immunofluorescence, were used to evaluate the role of PPARβ/δ in memory dysfunction. Our results showed a decrease in dendritic spine density and synaptic markers in PPARβ/δ-/- mice, which were corroborated in the NORT. Likewise, our study demonstrated that the lack of PPARβ/δ receptor enhances gliosis in the hippocampus, contributing to astrocyte and microglial activation and to the increase in neuroinflammatory biomarkers. Additionally, alterations in the hippocampal insulin receptor pathway were found. Interestingly, while some of the disturbances caused by the lack of PPARβ/δ were not affected by feeding the HFD, others were exacerbated or required the combination of both factors. Taken together, the loss of PPARβ/δ-/- affects neuronal and synaptic structure, contributing to memory dysfunction, and they also present this receptor as a possible new target for the treatment of memory impairment.

The omega-3 hydroxy fatty acid 7(S)-HDHA is a high-affinity PPARα ligand that regulates brain neuronal morphology

The nuclear receptor peroxisome proliferator-activated receptor alpha (PPARα) is emerging as an important target in the brain for the treatment or prevention of cognitive disorders. The identification of high-affinity ligands for brain PPARα may reveal the mechanisms underlying the synaptic effects of this receptor and facilitate drug development. Here, using an affinity purification-untargeted mass spectrometry (AP-UMS) approach, we identified an endogenous, selective PPARα ligand, 7(S)-hydroxy-docosahexaenoic acid [7(S)-HDHA]. Results from mass spectrometric detection of 7(S)-HDHA in mouse and rat brain tissues, time-resolved FRET analyses, and thermal shift assays collectively revealed that 7(S)-HDHA potently activated PPARα with an affinity greater than that of other ligands identified to date. We also found that 7(S)-HDHA activation of PPARα in cultured mouse cortical neurons stimulated neuronal growth and arborization, as well as the expression of genes associated with synaptic plasticity. The findings suggest that this DHA derivative supports and enhances neuronal synaptic capacity in the brain.

PPARα Signaling: A Candidate Target in Psychiatric Disorder Management

Peroxisome proliferator-activator receptors (PPARs) regulate lipid and glucose metabolism, control inflammatory processes, and modulate several brain functions. Three PPAR isoforms have been identified, PPARα, PPARβ/δ, and PPARγ, which are expressed in different tissues and cell types. Hereinafter, we focus on PPARα involvement in the pathophysiology of neuropsychiatric and neurodegenerative disorders, which is underscored by PPARα localization in neuronal circuits involved in emotion modulation and stress response, and its role in neurodevelopment and neuroinflammation. A multiplicity of downstream pathways modulated by PPARα activation, including glutamatergic neurotransmission, upregulation of brain-derived neurotrophic factor, and neurosteroidogenic effects, encompass mechanisms underlying behavioral regulation. Modulation of dopamine neuronal firing in the ventral tegmental area likely contributes to PPARα effects in depression, anhedonia, and autism spectrum disorder (ASD). Based on robust preclinical evidence and the initial results of clinical studies, future clinical trials should assess the efficacy of PPARα agonists in the treatment of mood and neurodevelopmental disorders, such as depression, schizophrenia, and ASD.

Targeting Nuclear Receptors in Lung Cancer—Novel Therapeutic Prospects

Lung cancer, the second most commonly diagnosed cancer, is the major cause of fatalities worldwide for both men and women, with an estimated 2.2 million new incidences and 1.8 million deaths, according to GLOBOCAN 2020. Although various risk factors for lung cancer pathogenesis have been reported, controlling smoking alone has a significant value as a preventive measure. In spite of decades of extensive research, mechanistic cues and targets need to be profoundly explored to develop potential diagnostics, treatments, and reliable therapies for this disease. Nuclear receptors (NRs) function as transcription factors that control diverse biological processes such as cell growth, differentiation, development, and metabolism. The aberrant expression of NRs has been involved in a variety of disorders, including cancer. Deregulation of distinct NRs in lung cancer has been associated with numerous events, including mutations, epigenetic modifications, and different signaling cascades. Substantial efforts have been made to develop several small molecules as agonists or antagonists directed to target specific NRs for inhibiting tumor cell growth, migration, and invasion and inducing apoptosis in lung cancer, which makes NRs promising candidates for reliable lung cancer therapeutics. The current work focuses on the importance of various NRs in the development and progression of lung cancer and highlights the different small molecules (e.g., agonist or antagonist) that influence NR expression, with the goal of establishing them as viable therapeutics to combat lung cancer.

PPARδ Activation Mitigates 6-OHDA-Induced Neuronal Damage by Regulating Intracellular Iron Levels

Intracellular iron accumulation in dopaminergic neurons contributes to neuronal cell death in progressive neurodegenerative disorders such as Parkinson’s disease. However, the mechanisms of iron homeostasis in this context remain incompletely understood. In the present study, we assessed the role of the nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ) in cellular iron homeostasis. We identified that PPARδ inhibited 6-hydroxydopamine (6-OHDA)-triggered neurotoxicity in SH-SY5Y neuroblastoma cells. PPARδ activation with GW501516, a specific PPARδ agonist, mitigated 6-OHDA-induced neuronal damage. Further, PPARδ activation also suppressed iron accumulation, which contributes to 6-OHDA-induced neuronal damage. PPARδ activation attenuated 6-OHDA-induced neuronal damage in a similar manner to that of the iron chelator deferoxamine. We further elucidated that PPARδ modulated cellular iron homeostasis by regulating expression of divalent metal transporter 1, ferroportin 1, and ferritin, but not transferrin receptor 1, through iron regulatory protein 1 in 6-OHDA-treated cells. Interestingly, PPARδ activation suppressed 6-OHDA-triggered generation of reactive oxygen species and lipid peroxides. The effects of GW501516 were abrogated by shRNA knockdown of PPARδ, indicating that the effects of GW501516 were PPARδ-dependent. Taken together, these findings suggest that PPARδ attenuates 6-OHDA-induced neurotoxicity by preventing intracellular iron accumulation, thereby suppressing iron overload-associated generation of reactive oxygen species and lipid peroxides, key mediators of ferroptotic cell death.

Effects of Intra-BLA Administration of PPAR Antagonists on Formalin-Evoked Nociceptive Behaviour, Fear-Conditioned Analgesia, and Conditioned Fear in the Presence or Absence of Nociceptive Tone in Rats

There is evidence for the involvement of peroxisome proliferator-activated receptors (PPARs) in pain, cognition, and anxiety. However, their role in pain–fear interactions is unknown. The amygdala plays a key role in pain, conditioned fear, and fear-conditioned analgesia (FCA). We investigated the effects of intra-basolateral amygdala (BLA) administration of PPARα, PPARβ/δ, and PPARγ antagonists on nociceptive behaviour, FCA, and conditioned fear in the presence or absence of nociceptive tone. Male Sprague-Dawley (SD) rats received footshock (FC) or no footshock (NFC) in a conditioning arena. Twenty-three and a half hours later, rats received an intraplantar injection of formalin or saline and, 15 min later, intra-BLA microinjections of vehicle, PPARα (GW6471) PPARβ/δ (GSK0660), or PPARγ (GW9662) antagonists before arena re-exposure. Pain and fear-related behaviour were assessed, and neurotransmitters/endocannabinoids measured post-mortem. Intra-BLA administration of PPARα or PPARγ antagonists potentiated freezing in the presence of nociceptive tone. Blockade of all PPAR subtypes in the BLA increased freezing and BLA dopamine levels in NFC rats in the absence of nociceptive tone. Administration of intra-BLA PPARα and PPARγ antagonists increased levels of dopamine in the BLA compared with the vehicle-treated counterparts. In conclusion, PPARα and PPARγ in the BLA play a role in the expression or extinction of conditioned fear in the presence or absence of nociceptive tone.

Diabetes mellitus and Parkinson's disease: dangerous liaisons between insulin and dopamine

The relationship between diabetes mellitus and Parkinson's disease has been described in several epidemiological studies over the 1960s to date. Molecular studies have shown the possible functional link between insulin and dopamine, as there is strong evidence demonstrating the action of dopamine in pancreatic islets, as well as the insulin effects on feeding and cognition through central nervous system mechanism, largely independent of glucose utilization. Therapies used for the treatment of type 2 diabetes mellitus appear to be promising candidates for symptomatic and/or disease-modifying action in neurodegenerative diseases including Parkinson's disease, while an old dopamine agonist, bromocriptine, has been repositioned for the type 2 diabetes mellitus treatment. This review will aim at reappraising the different studies that have highlighted the dangerous liaisons between diabetes mellitus and Parkinson's disease.

The endocannabinoid system and related lipids as potential targets for the treatment of migraine-related pain

BACKGROUND

Migraine is a complex and highly disabling neurological disease whose treatment remains challenging in many patients, even after the recent advent of the first specific-preventive drugs, namely monoclonal antibodies that target calcitonin gene-related peptide. For this reason, headache researchers are actively searching for new therapeutic targets. Cannabis has been proposed for migraine treatment, but controlled clinical studies are lacking. A major advance in cannabinoid research has been the discovery of the endocannabinoid system (ECS), which consists of receptors CB1 and CB2; their endogenous ligands, such as N-arachidonoylethanolamine; and the enzymes that catalyze endocannabinoid biosynthesis or degradation. Preclinical and clinical findings suggest a possible role for endocannabinoids and related lipids, such as palmitoylethanolamide (PEA), in migraine-related pain treatment. In animal models of migraine-related pain, endocannabinoid tone modulation via inhibition of endocannabinoid-catabolizing enzymes has been a particular focus of research.

METHODS

To conduct a narrative review of available data on the possible effects of cannabis, endocannabinoids, and other lipids in migraine-related pain, relevant key words were used to search the PubMed/MEDLINE database for basic and clinical studies.

RESULTS

Endocannabinoids and PEA seem to reduce trigeminal nociception by interacting with many pathways associated with migraine, suggesting a potential synergistic or similar effect.

CONCLUSIONS

Modulation of the metabolic pathways of the ECS may be a basis for new migraine treatments. The multiplicity of options and the wealth of data already obtained in animal models underscore the importance of further advancing research in this area. Multiple molecules related to the ECS or to allosteric modulation of CB1 receptors have emerged as potential therapeutic targets in migraine-related pain. The complexity of the ECS calls for accurate biochemical and pharmacological characterization of any new compounds undergoing testing and development.

Peroxisome Proliferator-Activated Receptor Alpha (PPAR-α) as a Regulator of the Angiogenic Profile of Endometriotic Lesions

Endometriosis is a disease that affects a significant proportion of women and its infiltrative pattern is entirely dependent on the vascular supply of lesions. Several factors seem to trigger the process of angiogenesis in endometriotic lesions. During the last years, peroxisome proliferator-activated receptors (PPARs), a group of nuclear proteins that regulate gene transcription and that seem to regulate energy consumption and expenditure, have been also implicated in the pathophysiology of angiogenesis. Their ability to regulate the course of cancer and improve the survival rates of patients has been extensively studied and seems to be partially dependent on alteration of the vascular supply of malignant lesions. Research in the field of endometriosis is scarce in the international literature and mainly focused on PPAR-gamma. However, indirect evidence suggests that PPAR-alpha (PPAR-α) may also regulate the vascular supply of endometriotic lesions as well. Specifically, PPAR-α agonists seem to downregulate angiogenesis by increasing the expression of several anti-angiogenic molecules, including thrombospondin-1 (TSP-1) and gypenoside 140 (gp140), as well as factors that are involved in the mitogen-activated protein kinase cascade. In the present article, we summarize existing indirect and direct evidence that indicates the existence of an association between the expression of PPAR-α and endometriosis to help future research in this field.

The Effects of Rosiglitazone on Task Specific Anxiety-Like Behavior and Novelty Seeking in a Model of Chronic Adolescent Unpredictable Stress

Adolescence is characterized as a period of increased social behavior, risk taking, and novelty seeking, partly due to ongoing maturation in critical brain areas and the hypothalamic-pituitary-adrenal (HPA) negative-feedback system. During this period there is heightened vulnerability to stress that can drive neuro-immune-endocrine remodeling, resulting in the emergence of maladaptive behaviors that increase susceptibility to alcohol and substance abuse. Here we used a rat model to investigate the impact of chronic adolescent unpredictable stress on a battery of behavioral measures to assess anxiety, novelty seeking, risk taking, depression, and voluntary ethanol consumption while determining whether the PPARγ agonist rosiglitazone can attenuate these effects. Adolescent female rats that experienced stress showed increased risk taking behavior and novelty seeking behavior with no change in ethanol consumption. The administration of rosiglitazone during stress induction attenuated stress-induced cortisol elevation, normalized risk taking behavior in a model anxiety, and attenuated novelty seeking in a task-specific manner. Depressive-like behavior was not impacted by adolescent unpredictable stress or the administration of rosiglitazone. The results from this study demonstrate that exposure to unpredictable stress during adolescence increases the prevalence of maladaptive behaviors that are known to increase susceptibility to alcohol and substance abuse, and that rosiglitazone may be an effective therapeutic to attenuate the emergence of select risk taking and novelty seeking behaviors in females.

Rewarding effect of ethanol-induced conditioned place preference in mice: Effect of the monoterpenoid linalool

Alcohol addiction is a chronic relapsing disease that is progressive and has severe detrimental health outcomes. The use of natural products has become popular for the treatment of side effects of drugs and substance abuse. Linalool is a monoterpenoid that exhibits several effects on the central nervous system. Linalool was identified to have beneficial effects on different mechanisms that are relevant in drug addiction or substance use disorder. The primary aim of the present study was to evaluate the therapeutic effect of linalool on the rewarding properties of alcohol in mice. Conditioned place preference (CPP) was established by intraperitoneal (i.p.) injection of ethanol (2 g/kg) during an 8-day conditioning trial. The effects of acamprosate and linalool on the rewarding properties of ethanol were tested in mice who received linalool (12.5, 25, and 50 mg/kg, i.p.) and acamprosate (300 mg/kg, i.p.) 30 min before each ethanol injection. CPP was extinguished by repeated testing, throughout which conditioned mice were administered daily linalool. Mice were lastly examined for reinstatement provoked by i.p. administration of single low-dose ethanol (0.4 g/kg, i.p.). Treatment with linalool reduced the acquisition and reinstatement, and precipitated the extinction of ethanol-induced CPP in mice. Acquisition and reinstatement of alcohol-induced CPP were significantly reduced by acamprosate, which also precipitated extinction. Ethanol alone and the combination with linalool or acamprosate did not alter locomotor activity. The results of this study suggest that linalool may have pharmacological effects for the treatment of alcohol addiction. In addition, further investigation is required to fully explore the benefits and possible adverse effects of linalool on alcohol addiction.

Cannabidiol and substance use disorder: Dream or reality

BACKGROUND

Cannabidiol (CBD) is one of the major constituents of Cannabis sativa L. that lacks psychotomimetic and rewarding properties and inhibits the rewarding and reinforcing effects of addictive drugs such as cocaine, methamphetamine (METH), and morphine. Additionally, CBD's safety profile and therapeutic potential are currently evaluated in several medical conditions, including pain, depression, movement disorders, epilepsy, multiple sclerosis, Alzheimer's disease, ischemia, and substance use disorder. There is no effective treatment for substance use disorders such as addiction, and this review aims to describe preclinical and clinical investigations into the effects of CBD in various models of opioid, psychostimulant, cannabis, alcohol, and nicotine abuse. Furthermore, the possible mechanisms underlying the therapeutic potential of CBD on drug abuse disorders are reviewed.

METHODS

The current review considers and summarizes the preclinical and clinical investigations into CBD's effects in various models of drug abuse include opioids, psychostimulants, cannabis, alcohol, and nicotine.

RESULTS

Several preclinical and clinical studies have proposed that CBD may be a reliable agent to inhibit the reinforcing and rewarding impact of drugs.

CONCLUSIONS

While the currently available evidence converges to suggest that CBD could effectively reduce the rewarding and reinforcing effects of addictive drugs, more preclinical and clinical studies are needed before CBD can be added to the therapeutic arsenal for treating addiction.

Physospermum cornubienseL. alleviates nociceptive and neuropathic pain: Evidences and possible mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

In Iranian/Persian folkloric medicine, Physospermum cornubiense (Shokaran Baghi in Persian) is used for the treatment of pain and inflammation.

OBJECTIVE

This modern examination included Swiss mice to investigate the anti-neuropathic and anti-nociceptive effects of Physospermum cornubiense essential oil (PCEO).

MATERIALS AND METHODS

To determine PCEO 's anti-nociceptive function in formalin-induced paw licking (FML) paradigm, researchers looked at the arginine-nitric oxide and potassium channels pathway in addition to involvements of more specific examples of receptors such as adrenergic, opioid, cannabinoid, peroxisome proliferator-activated (PPA), and transient receptor potential vanilloid. The CVC or cervical spinal cord contusion exemplar has also been used to induce neuropathic pain.

RESULTS

PCEO (450mg/kg) relative to control mice in the phase_ II of FML exemplar provided strong antinociception (p < 0.001). Furthermore, pre-treatments with arginine, glibenclamide, methylene blue, L-NAME, SNP, GW6471, naloxonazine, and GW9662 (p < 0.05) returned the PCEO antinociceptive response in the FML (inflammatory phase) model. Orally limonene administration significantly diminished (p < 0.001) acute pain in inflammatory phase of FML test. Moreover, the von Frey test indicated that both PCEO and limonene could return neuropathic pain (mechanical allodynia) in CVC mice.

CONCLUSION

The results obtained from this study, together with literature, give evidence of properties of PCEO for therapy of antinociceptive and neuropathic pain.