Peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ): Molecular Effects and Its Importance as a Novel Therapeutic Target for Cerebral Ischemic Injury

Unlocking the cellular mystery: how proton pump inhibitors may alter the dementia landscape

Proton pump inhibitors (PPIs) have become virtually the sole class of histamine-2 receptor antagonists due to their greater effectiveness and general availability. However, concern has been increasing about long-term use and some possible neurological adverse effects, including a link with dementia. Several studies indicate that long-term use of PPIs can raise the risk for both Alzheimer's disease (AD) and non-Alzheimer's dementia, though there is opposing evidence. Neurological side effects of PPIs are cognitive impairment, neuropathies, depression, anxiety, and hallucinations. The mechanisms are unknown but could be due to PPIs crossing the BBB and interfering with neuronal function or causing systemic deficiencies, e.g., vitamin B12 deficiency. Vitamin B12 is essential for cognitive function, and its deficiency has been linked to dementia. PPIs also cause B12 deficiency by inhibiting gastric acid secretion, which is required for B12 absorption. B12 deficiency causes hyperhomocysteinemia, which facilitates tau hyperphosphorylation and amyloid-β (Aβ) deposition, major pathological hallmarks of AD. PPIs have also been found to disrupt amyloid precursor protein processing, mitochondrial function, and neuroinflammation, further enhancing neurodegenerative processes. Experimental evidence indicates that PPIs affect brain homeostasis through inhibition of vacuolar ATPases, modulation of microglial Aβ phagocytosis, and induction of synaptic dysfunction. While the specific molecular mechanisms are unknown, findings suggest that long-term PPI exposure could contribute to neurodegeneration, especially in elderly patients. With increasing dementia prevalence, additional clinical research is needed to ascertain whether PPIs are a causative agent or a contributing factor to cognitive impairment.

Pioglitazone mitigates acetic acid-induced colitis in rats via epigenetic-modulation and antioxidant mechanisms

Ulcerative colitis (UC) is one of the inflammatory bowel diseases characterized by colonic damage. Epigenetic mechanisms are suggested to play a role in the pathogenesis of UC. Pioglitazone has shown promise for the treatment of UC; however, the role of epigenetic pathways in this effect is unclear. The current study aimed to explore the therapeutic and protective effects of pioglitazone against acetic acid-induced colitis (AA-C) in rats and the role of epigenetic modulation and antioxidant mechanisms in this effect. Forty male albino rats were divided into four groups (n = 10/group): control (normal saline), acetic-acid-induced ulcerative colitis (AA-C) (3 days, 2 ml acetic acid 4%), pioglitazone-treated (AA, followed by 3-week oral pioglitazone 25 mg/kg/day), and pioglitazone-protected groups (3-day oral pioglitazone 25 mg/kg/day before AA, continued with AA, and 3 weeks later). After the experiment, the body weight, colon weight-to-length ratio, and colonic tissue were evaluated. The colonic expression of epigenetic markers (DNA methyltransferase- 1 and methylated E-cadherin), oxidative stress marker (malondialdehyde), antioxidant enzyme (superoxide dismutase), and angiotensin-converting enzyme- 2 (ACE- 2) was evaluated. The pioglitazone-protected and treated groups showed significant inhibition of DNA methyltransferase- 1 and methylated E-cadherin with improvement in colonic tissue macroscopic and microscopic signs of inflammation, improved weight, less oxidative stress, and less ACE- 2 expression. These beneficial actions were more pronounced among the pioglitazone-protected group. Pioglitazone could mitigate AA-C in rats by inhibiting epigenetic DNA methyltransferase- 1 and E-cadherin gene methylation. It also inhibits oxidative stress and prevents the overexpression of ACE- 2.

α-amanitin induces hepatotoxicity via PPAR-γ inhibition and NLRP3 inflammasome activation

Mushroom poisoning, predominantly caused by α-amanitin, is a critical food safety concern in worldwide, with severe cases leading to hepatotoxicity and fatalities. This study delves into the hepatotoxic effects of α-amanitin, focusing on the NLRP3 inflammasome and PPAR-γ's regulatory role in inflammation. In vitro studies with L-02 cells showed that α-amanitin reduces cell viability and triggers NLRP3 inflammasome activation, increasing NF-κB phosphorylation and pro-inflammatory cytokines IL-18 and IL-1β. The NLRP3 inhibitor MCC950 mitigated these effects without impacting NF-κB. Conversely, PPAR-γ knockdown intensified the inflammatory response. In vivo, α-amanitin induced dose-dependent liver injury in mice, evident by elevated serum ALT and AST, and histological liver damage. MCC950 pretreatment offered protection against hepatotoxicity, while PPAR-γ inhibition with GW9662 worsened the condition. The study highlights the interplay between α-amanitin, NLRP3, and PPAR-γ in hepatotoxicity, proposing potential therapeutic targets for mushroom poisoning-induced liver diseases.

Emerging targets in amyotrophic lateral sclerosis (ALS): The promise of ATP-binding cassette (ABC) transporter modulation

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative primarily affecting motor neurons, leading to disability and neuronal death, and ATP-Binding Cassette (ABC) transporter due to their role in drug efflux and modulation of various cellular pathways contributes to the pathogenesis of ALS. In this article, we extensively investigated various molecular and mechanistic pathways linking ALS transporter to the pathogenesis of ALS; this involves inflammatory pathways such as Mitogen-Activated Protein Kinase (MAPK), Phosphatidylinositol-3-Kinase/Protein Kinase B (PI3K/Akt), Toll-Like Receptor (TLR), Glycogen Synthase Kinase 3β (GSK-3β), Nuclear Factor Kappa-B (NF-κB), and Cyclooxygenase (COX). Oxidative pathways such as Astrocytes, Glutamate, Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), Sirtuin 1 (SIRT-1), Forkhead box protein O (FOXO), Extracellular signal-regulated kinase (ERK). Additionally, we delve into the role of autophagic pathways like TAR DNA-binding protein 43 (TDP-43), AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and lastly, the apoptotic pathways. Furthermore, by understanding these intricate interactions, we aim to develop novel therapeutic strategies targeting ABC transporters, improving drug delivery, and ultimately offering a promising avenue for treating ALS.

Astragaloside IV plays a neuroprotective role by promoting PPARγ in cerebral ischemia-reperfusion rats

BACKGROUND

Cerebral ischemia-reperfusion injury (CIRI) usually occurs during the treatment phase of ischemic disease, which is closely related to high morbidity and mortality. Promoting neurogenesis and synaptic plasticity are effective neural recovery strategies for CIRI. Astragaloside IV (AS-IV) has been shown to play a neuroprotective role in some neurological diseases. In the current study, we evaluated the effect and possible mechanism of AS-IV in CIRI rats.

METHODS

The middle cerebral artery occlusion reperfusion (MCAO/R) model was established in rats to simulate the occurrence of human CIRI. First, we determined the cerebral injury on the 1st, 3rd, 5th and 7th day after cerebral ischemia-reperfusion (I/R) surgery by neurological deficit detection, TTC staining, TUNEL staining and Western blot analysis. Furthermore, rats were pre administered with AS-IV and then subjected to cerebral I/R surgery. Brains were collected on the 3rd day to evaluate the neuroprotective effect of AS-IV.

RESULTS

Our results showed that on the 3rd day after I/R, the neurological impairment score and infarct volume were highest, the levels of apoptosis and expression of Caspase3 and Bax reached the peak. AS-IV treatment apparently attenuated neurological dysfunction, reduced infarct volume and pathological damage, promoted the neurogenesis, and alleviated the pathological damage caused by cerebral I/R involved in thickening and blurring of synaptic membranes, reduction of microtubules and synaptic vesicles, and loss of synaptic cleft. Our study also showed that AS-IV promoted the transcription and expression of the peroxisome proliferators-activated receptors γ (PPARγ) and brain-derived neurotrophic factor (BDNF), increased the expression of phosphorylation of tyrosine kinase receptor B (TrkB) and downstream PI3K/Akt/mTOR pathway proteins. Notably, when GW9662, an inhibitor of PPARγ was administered with AS-IV, the neuroprotective effect of AS-IV was reduced.

CONCLUSIONS

These findings suggested that AS-IV has neuroprotective function in CIRI rats, and its molecular mechanism may depend on the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (PKB)/Akt signalling pathway activated by PPARγ. AS-IV could be an effective therapeutic drug candidate for CIRI treatment.

Diabetic Cardiomyopathy: An Update on Emerging Pathological Mechanisms

Diabetic Cardiomyopathy (DCM) is a notable consequence of diabetes mellitus, distinguished by cardiac dysfunction that occurs separately from coronary artery disease or hypertension. A recent study has revealed an intricate interaction of pathogenic processes that contribute to DCM. Important aspects involve the dysregulation of glucose metabolism, resulting in heightened oxidative stress and impaired mitochondrial function. In addition, persistent high blood sugar levels stimulate inflammatory pathways, which contribute to the development of heart fibrosis and remodelling. Additionally, changes in the way calcium is managed and the presence of insulin resistance are crucial factors in the formation and advancement of DCM. This may be due to the involvement of many molecular mechanistic pathways such as NLRP3, NF-κB, PKC, and MAPK with their downstream associated signaling pathways. Gaining a comprehensive understanding of these newly identified pathogenic pathways is crucial in order to design precise therapy approaches that can enhance the results for individuals suffering from diabetes. In addition, this review offers an in-depth review of not just pathogenic pathways and molecular mechanistic pathways but also diagnostic methods, treatment options, and clinical trials.

Integrated Network Pharmacology and In-silico Approaches to Decipher the Pharmacological Mechanism of Dioscorea septemloba Thunb in Treating Gout and Its Complications

BACKGROUND

Dioscorea septemloba Thunb. (DST) has demonstrated therapeutic potential in the treatment of gout and its associated complications. However, the underlying mechanisms of DST's pharmacological activity remain unclear. This study aims to investigate the pharmacological substances and network regulatory mechanisms of DST in treating gout and its complications using network pharmacology.

METHODS

According to ultra-high performance liquid chromatography coupled with hybrid quadrupole-Orbitrap mass spectrometry (UPLC-Q-Exactive Orbitrap-MS) data and Lipinski's rule of five, 24 bioactive phytochemicals from DST were identified. The targets of gout were retrieved from Gene Expression Omnibus (GEO), GeneCards, and DisGeNET databases, followed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG pathway) enrichment analysis. The Cytoscape network analysis was used to identify the primary pathological pathways and key targets. Finally, LeDock was used for molecular docking to verify the active components of DST and their core target proteins.

RESULTS

DST contains several core active ingredients, such as tetrahydroimidazo[1,2-a]pyridine- 2,5-dione, diosgenin, beta-sitosterol, dioscorol B, montroumarin and 9,10-dihydro-5,7- dimethoxy-3,4-phenanthrenediol. Moreover, these active components were found to strongly bind to the key targets for treating gout and its complications, including HSP90AA1, STAT3, PTGS2, PPARG, MTOR, HIF1A, MMP9, ESR1, and TLR4. As a result, DST alleviates gout and its complications by inhibiting xanthine dehydrogenase (XDH) to reduce uric acid levels and regulating the HIF-1α, EZH2/STAT3, and COX-2/PPAR-γ pathways to reduce inflammation. Additionally, it also plays an analgesic role by regulating the neuroactive ligand-receptor interaction pathway and calcium ion signaling pathway.

CONCLUSION

This study has provided insights into the underlying mechanisms of DST in the treatment of gout and its complications, which could serve as a scientific foundation for its clinical translation.

Nrf2 and Ferroptosis: Exploring Translational Avenues for Therapeutic Approaches to Neurological Diseases

Nrf2, a crucial protein involved in defense mechanisms, particularly oxidative stress, plays a significant role in neurological diseases (NDs) by reducing oxidative stress and inflammation. NDs, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, stroke, epilepsy, schizophrenia, depression, and autism, exhibit ferroptosis, iron-dependent regulated cell death resulting from lipid and iron-dependent reactive oxygen species (ROS) accumulation. Nrf2 has been shown to play a critical role in regulating ferroptosis in NDs. Age-related decline in Nrf2 expression and its target genes (HO-1, Nqo-1, and Trx) coincides with increased iron-mediated cell death, leading to ND onset. The modulation of iron-dependent cell death and ferroptosis by Nrf2 through various cellular and molecular mechanisms offers a potential therapeutic pathway for understanding the pathological processes underlying these NDs. This review emphasizes the mechanistic role of Nrf2 and ferroptosis in multiple NDs, providing valuable insights for future research and therapeutic approaches.

Aquaporin proteins: A promising frontier for therapeutic intervention in cerebral ischemic injury

Cerebral ischemic injury is characterized by reduced blood flow to the brain, remains a significant cause of morbidity and mortality worldwide. Despite improvements in therapeutic approaches, there is an urgent need to identify new targets to lessen the effects of ischemic stroke. Aquaporins, a family of water channel proteins, have recently come to light as promising candidates for therapeutic intervention in cerebral ischemic injury. There are 13 aquaporins identified, and AQP4 has been thoroughly involved with cerebral ischemia as it has been reported that modulation of AQP4 activity can offers a possible pathway for therapeutic intervention along with their role in pH, osmosis, ions, and the blood-brain barrier (BBB) as possible therapeutic targets for cerebral ischemia injury. The molecular pathways which can interacts with particular cellular pathways, participation in neuroinflammation, and possible interaction with additional proteins thought to be involved in the etiology of a stroke. Understanding these pathways offers crucial information on the diverse role of AQPs in cerebral ischemia, paving the door for the development of focused/targeted therapeutics.

Mechanistic exploration of ubiquitination-mediated pathways in cerebral ischemic injury

The ubiquitin-proteasome system (UPS) plays a pivotal role in regulating protein homeostasis and cellular processes, including protein degradation, trafficking, DNA repair, and cell signaling. During cerebral ischemia, ischemic conditions profoundly disrupt UPS activity, leading to proteasomal dysfunction and the accumulation of abnormal proteins. This imbalance contributes to neuronal injury and cell death observed in ischemic stroke. The UPS is intricately linked to various signaling pathways crucial for neuronal survival, inflammation, and cellular stress response, such as NF-κB, TRIM, TRIP, JAK-STAT, PI3K/Akt, and ERK1/2. Alterations in the ubiquitination process can significantly impact the activation and regulation of these pathways, exacerbating ischemic brain injury. Therapeutic approaches targeting the UPS in cerebral ischemia aim to rebalance protein levels, reduce proteotoxic stress, and mitigate neuronal injury. Strategies include proteasome inhibition, targeting specific ubiquitin ligases and deubiquitinating enzymes, and modulating ubiquitination-mediated regulation of key signaling pathways implicated in ischemia-induced pathophysiology. Therefore, the present review discusses the molecular mechanisms underlying UPS dysfunction in ischemic stroke is crucial for developing effective therapeutic interventions. Modulating ubiquitination-mediated pathways through therapeutic interventions targeting specific UPS components holds significant promise for mitigating ischemic brain injury and promoting neuroprotection and functional recovery in patients with cerebral ischemia.

The Neuroprotective Mechanisms of PPAR-γ: Inhibition of Microglia-Mediated Neuroinflammation and Oxidative Stress in a Neonatal Mouse Model of Hypoxic-Ischemic White Matter Injury

BACKGROUND

Neuroinflammation and oxidative stress, mediated by microglial activation, hinder the development of oligodendrocytes (OLs) and delay myelination in preterm infants, leading to white matter injury (WMI) and long-term neurodevelopmental sequelae. Peroxisome proliferator-activated receptor gamma (PPAR-γ) has been reported to inhibit inflammation and oxidative stress via modulating microglial polarization in various central nervous system diseases. However, the relationship between PPAR-γ and microglial polarization in neonatal WMI is not well understood. Therefore, this study aimed to elucidate the role and mechanisms of PPAR-γ in preterm infants affected by WMI.

METHODS

In this study, an in vivo hypoxia-ischemia (HI) induced brain WMI neonatal mouse model was established. The mice were administered intraperitoneally with either RSGI or GW9662 to activate or inhibit PPAR-γ, respectively. Additionally, an in vitro oxygen-glucose deprivation (OGD) cell model was established and pretreated with pcDNA 3.1-PPAR-γ or si-PPAR-γ to overexpress or silence PPAR-γ, respectively. The neuroprotective effects of PPAR-γ were investigated in vivo. Firstly, open field test, novel object recognization test, and beam-walking test were employed to assess the effects of PPAR-γ on neurobehavioral recovery. Furthermore, assessment of OLs loss and OL-maturation disorder, the number of myelinated axons, myelin thickness, synaptic deficit, activation of microglia and astrocyte, and blood-brain barrier (BBB) were used to evaluate the effects of PPAR-γ on pathological repair. The mechanisms of PPAR-γ were explored both in vivo and in vitro. Assessment of microglia polarization, inflammatory mediators, reactive oxygen species (ROS), MDA, and antioxidant enzymes was used to evaluate the anti-inflammatory and antioxidative effects of PPAR-γ activation. An assessment of HMGB1/NF-κB and NRF2/KEAP1 signaling pathway was conducted to clarify the mechanisms by which PPAR-γ influences HI-induced WMI in neonatal mice.

RESULTS

Activation of PPAR-γ using RSGI significantly mitigated BBB disruption, promoted M2 polarization of microglia, inhibited activation of microglia and astrocytes, promoted OLs development, and enhanced myelination in HI-induced WMI. Conversely, inhibition of PPAR-γ using GW9662 further exacerbated the pathologic hallmark of WMI. Neurobehavioral tests revealed that neurological deficits were ameliorated by RSGI, while further aggravated by GW91662. In addition, activation of PPAR-γ significantly alleviated neuroinflammation and oxidative stress by suppressing HMGB1/NF-κB signaling pathway and activating NRF2 signaling pathway both in vivo and in vitro. Conversely, inhibition of PPAR-γ further exacerbated HI or OGD-induced neuroinflammation, oxidative stress via modulation of the same signaling pathway.

CONCLUSIONS

Our findings suggest that PPAR-γ regulates microglial activation/polarization as well as subsequent neuroinflammation/oxidative stress via the HMGB1/NF-κB and NRF2/KEAP1 signaling pathway, thereby contributing to neuroprotection and amelioration of HI-induced WMI in neonatal mice.

PPARγ Agonist Rosiglitazone and Antagonist GW9662: Antihypertensive Effects on Chronic Intermittent Hypoxia-Induced Hypertension in Rats

The increased incidence of hypertension associated with obstructive sleep apnea (OSA) presents significant physical, psychological, and economic challenges. Peroxisome proliferator-activated receptor gamma (PPARγ) plays a role in both OSA and hypertension, yet the therapeutic potential of PPARγ agonists and antagonists for OSA-related hypertension remains unexplored. Therefore, we constructed a chronic intermittent hypoxia (CIH)-induced hypertension rat model that mimics the pathogenesis of OSA-related hypertension in humans. The model involved administering PPARγ agonist rosiglitazone (RSG), PPARγ antagonist GW9662, or normal saline, followed by regular monitoring of blood pressure and thoracic aorta analysis using staining and electron microscopy. Intriguingly, our results indicated that both RSG and GW9662 appeared to potently counteract CIH-induced hypertension. In silico study suggested that GW9662's antihypertensive effect might mediated through angiotensin II receptor type 1 (AGTR1). Our findings provide insights into the mechanisms of OSA-related hypertension and propose novel therapeutic targets.

Unlocking new avenues for neuropsychiatric disease therapy: the emerging potential of Peroxisome proliferator-activated receptors as promising therapeutic targets

RATIONALE

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate various physiological processes such as inflammation, lipid metabolism, and glucose homeostasis. Recent studies suggest that targeting PPARs could be beneficial in treating neuropsychiatric disorders by modulating neuronal function and signaling pathways in the brain. PPAR-α, PPAR-δ, and PPAR-γ have been found to play important roles in cognitive function, neuroinflammation, and neuroprotection. Dysregulation of PPARs has been associated with neuropsychiatric disorders like bipolar disorder, schizophrenia, major depression disorder, and autism spectrum disorder. The limitations and side effects of current treatments have prompted research to target PPARs as a promising novel therapeutic strategy. Preclinical and clinical studies have shown the potential of PPAR agonists and antagonists to improve symptoms associated with these disorders.

OBJECTIVE

This review aims to provide an overview of the current understanding of PPARs in neuropsychiatric disorders, their potential as therapeutic targets, and the challenges and future directions for developing PPAR-based therapies.

METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out with the keywords "PPAR, Neuropsychiatric disorders, Oxidative stress, Inflammation, Bipolar Disorder, Schizophrenia, Major depression disorder, Autism spectrum disorder, molecular pathway".

RESULT & CONCLUSION

Although PPARs present a hopeful direction for innovative therapeutic approaches in neuropsychiatric conditions, additional research is required to address obstacles and convert this potential into clinically viable and individualized treatments.

Interrogating the estrogen-mediated regulation of adrenocortical Klotho expression using ovariectomized albino rat model exposed to repeated restraint stress

Reproductive aging is associated with altered stress response and many other menopausal symptoms. Little is known about the adrenal expression of the anti-aging protein Klotho or how it is modulated by estrogen in ovariectomized stressed rats. Fifty-six Wistar female rats were assigned into seven equal groups. Sham-operated (Sham), sham stressed (Sham/STS), ovariectomized (OVR), ovariectomized stressed (OVR/STS), ovariectomized stressed rosiglitazone-treated (OVR/STS/R), ovariectomized stressed estrogen-treated (OVR/STS/E), and ovariectomized stressed estrogen/GW9662 co-treated (OVR/STS/E/GW) groups. All stressed rats were subjected daily to a one-hour restraint stress test for 19 days. At the end of the experiment, blood was collected for serum corticosterone (CORT) analysis. Adrenal tissues were obtained and prepared for polymerase chain reaction (PCR) assay, hematoxylin and eosin (H&E), immunohistochemistry-based identification of Klotho and PPAR-γ, and Oil Red O (ORO) staining. The rise in serum CORT was negligible in the OVR/STS group, in contrast to the Sham/STS group. The limited CORT response in the former group was restored by estrogen and rosiglitazone and blocked by estrogen/GW9226 co-administration. ORO-staining revealed a more evident reduction in the adrenal fat in the OVR/STS group, which was reversed by estrogen and counteracted by GW. Also, there was a comparable expression pattern of Klotho and PPAR-γ in the adrenals. The adrenal Klotho decreased in the OVR/STS group, but was reversed by estrogen treatment. GW9226/estrogen co-treatment interfered with the regulatory effect of estrogen on Klotho. The study suggested modulation of the adrenal Kotho expression by estrogen, in the ovariectomized rats subjected to a restraint stress test. This estrogen-provided adrenal protection might be mediated by PPAR-γ activation.

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.

Function and Mechanism of Abscisic Acid on Microglia-Induced Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD), as a neurologically implemented disease with complex etiological factors, has a complex and variable pathogenesis. Accompanying further research, neuroinflammation has been found to be one of the possible factors in its pathogenesis. Microglia, as intrinsic immune cells in the brain, play an important role in maintaining microenvironmental homeostasis in the brain. However, over-activation of neurotoxic microglia in PD promotes neuroinflammation, which further increases dopaminergic (DA) neuronal damage and exacerbates the disease process. Therefore, targeting and regulating the functional state of microglia is expected to be a potential avenue for PD treatment. In addition, plant extracts have shown great potential in the treatment of neurodegenerative disorders due to their abundant resources, mild effects, and the presence of multiple active ingredients. However, it is worth noting that some natural products have certain toxic side effects, so it is necessary to pay attention to distinguish medicinal ingredients and usage and dosage when using to avoid aggravating the progression of diseases. In this review, the roles of microglia with different functional states in PD and the related pathways inducing microglia to transform into neuroprotective states are described. At the same time, it is discussed that abscisic acid (ABA) may regulate the polarization of microglia by targeting them, promote their transformation into neuroprotective state, reduce the neuroinflammatory response in PD, and provide a new idea for the treatment of PD and the selection of drugs.

PPAR agonists for the treatment of neuroinflammatory diseases

Peroxisome proliferator-activated receptors [PPARs; PPARα, PPARβ/δ (also known as PPARδ), and PPARγ] widely recognized for their important role in glucose/lipid homeostasis, have recently received significant attention due to their additional anti-inflammatory and neuroprotective effects. Several newly developed PPAR agonists have shown high selectivity for specific PPAR isoforms in vitro and in vivo, offering the potential to achieve desired therapeutic outcomes while reducing the risk of adverse effects. In this review, we discuss the latest preclinical and clinical studies of the activation of PPARs by synthetic, natural, and isoform-specific (full, partial, and dual) agonists for the treatment of neuroinflammatory diseases, including HIV-associated neurocognitive disorders (HAND), Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and cerebral ischemia.

Pharmacological modulation of Sonic Hedgehog signaling pathways in Angiogenesis: A mechanistic perspective

The Sonic hedgehog (SHh) signaling pathway is an imperative operating network that helps in regulates the critical events during the development processes like multicellular embryo growth and patterning. Disruptions in SHh pathway regulation can have severe consequences, including congenital disabilities, stem cell renewal, tissue regeneration, and cancer/tumor growth. Activation of the SHh signal occurs when SHh binds to the receptor complex of Patch (Ptc)-mediated Smoothened (Smo) (Ptc-smo), initiating downstream signaling. This review explores how pharmacological modulation of the SHh pathway affects angiogenesis through canonical and non-canonical pathways. The canonical pathway for angiogenesis involves the activation of angiogenic cytokines such as fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), placental growth factor (PGF), hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), stromal cell-derived factor 1α, transforming growth factor-β1 (TGF-β1), and angiopoietins (Ang-1 and Ang-2), which facilitate the process of angiogenesis. The Non-canonical pathway includes indirect activation of certain pathways like iNOS/Netrin-1/PKC, RhoA/Rock, ERK/MAPK, PI3K/Akt, Wnt/β-catenin, Notch signaling pathway, and so on. This review will provide a better grasp of the mechanistic approach of SHh in mediating angiogenesis, which can aid in the suppression of certain cancer and tumor growths.

Nuclear orphan receptors: A novel therapeutic agent in neuroinflammation

Orphan receptors constitute a historically varied subsection of a superfamily of nuclear receptors. Nuclear receptors regulate gene expression in response to ligand signals and are particularly alluring therapeutic targets for chronic illnesses. Neuroinflammation and neurodegenerative diseases have been linked to these orphan nuclear receptors. Preclinical and clinical evidence suggests that orphan receptors could serve as future targets in neuroinflammation, such as Parkinson's disease (PD), Alzheimer's Disease (AD), Huntington's Disease (HD), Multiple Sclerosis (MS), and Cerebral Ischemia. Given the therapeutic relevance of certain orphan receptors in a variety of disorders, their potential in neuroinflammation remains unproven. There is substantial evidence that ligand-activated transcription factors have great promise for preventing neurodegenerative and neurological disorders, with certain orphan nuclear receptors i.e., PPARγ, NR4As, and orphan GPCRs holding particularly high potential. Based on previous findings, we attempted to determine the contribution of PPAR, NR4As, and orphan GPCRs-regulated neuroinflammation to the pathogenesis of these disorders and their potential to become novel therapeutic targets.

Therapeutic implication of Sonic Hedgehog as a potential modulator in ischemic injury

Sonic Hedgehog (SHh) is a homology protein that is involved in the modeling and development of embryonic tissues. As SHh plays both protective and harmful roles in ischemia, any disruption in the transduction and regulation of the SHh signaling pathway causes ischemia to worsen. The SHh signal activation occurs when SHh binds to the receptor complex of Ptc-mediated Smoothened (Smo) (Ptc-smo), which initiates the downstream signaling cascade. This article will shed light on how pharmacological modifications to the SHh signaling pathway transduction mechanism alter ischemic conditions via canonical and non-canonical pathways by activating certain downstream signaling cascades with respect to protein kinase pathways, angiogenic cytokines, inflammatory mediators, oxidative parameters, and apoptotic pathways. The canonical pathway includes direct activation of interleukins (ILs), angiogenic cytokines like hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and hypoxia-inducible factor alpha (HIF-), which modulate ischemia. The non-canonical pathway includes indirect activation of certain pathways like mTOR, PI3K/Akt, MAPK, RhoA/ROCK, Wnt/-catenin, NOTCH, Forkhead box protein (FOXF), Toll-like receptors (TLR), oxidative parameters such as GSH, SOD, and CAT, and some apoptotic parameters such as Bcl2. This review provides comprehensive insights that contribute to our knowledge of how SHh impacts the progression and outcomes of ischemic injuries.

Docosahexaenoic Acid as Master Regulator of Cellular Antioxidant Defenses: A Systematic Review

Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid that benefits the prevention of chronic diseases. Due to its high unsaturation, DHA is vulnerable to free radical oxidation, resulting in several unfavorable effects, including producing hazardous metabolites. However, in vitro and in vivo investigations suggest that the relationship between the chemical structure of DHA and its susceptibility to oxidation may not be as clear-cut as previously thought. Organisms have developed a balanced system of antioxidants to counteract the overproduction of oxidants, and the nuclear factor erythroid 2-related factor 2 (Nrf2) is the key transcription factor identified for transmitting the inducer signal to the antioxidant response element. Thus, DHA might preserve the cellular redox status promoting the transcriptional regulation of cellular antioxidants through Nrf2 activation. Here, we systematically summarize the research on the possible role of DHA in controlling cellular antioxidant enzymes. After the screening process, 43 records were selected and included in this review. Specifically, 29 studies related to the effects of DHA in cell cultures and 15 studies concerned the effects of consumption or treatment with DHA in animal. Despite DHA's promising and encouraging effects at modulating the cellular antioxidant response in vitro/in vivo, some differences observed among the reviewed studies may be accounted for by the different experimental conditions adopted, including the time of supplementation/treatment, DHA concentration, and cell culture/tissue model. Moreover, this review offers potential molecular explanations for how DHA controls cellular antioxidant defenses, including involvement of transcription factors and the redox signaling pathway.

Co-Delivery of Therapeutics and Bioactive Gas Using a Novel Liposomal Platform for Enhanced Treatment of Acute Arterial Injury

Atherosclerosis is a complex, multi-stage disease characterized by pathological changes across the vascular wall. Endothelial dysfunction, inflammation, hypoxia, and vascular smooth muscle cell proliferation contribute to its progression. An effective strategy capable of delivering pleiotropic treatment to the vascular wall is essential to limit neointimal formation. Echogenic liposomes (ELIP), which can encapsulate bioactive gases and therapeutic agents, have the potential to deliver enhanced penetration and treatment efficacy for atherosclerosis. In this study, liposomes loaded with nitric oxide (NO) and rosiglitazone, a peroxisome proliferator-activated receptor agonist, were prepared using hydration, sonication, freeze-thawing, and pressurization. The efficacy of this delivery system was evaluated in a rabbit model of acute arterial injury induced by balloon injury to the common carotid artery. Intra-arterial administration of rosiglitazone/NO co-encapsulated liposomes (R/NO-ELIP) immediately following injury resulted in reduced intimal thickening after 14 days. The anti-inflammatory and anti-proliferative effects of the co-delivery system were investigated. These liposomes were echogenic, enabling ultrasound imaging to assess their distribution and delivery. R/NO-ELIP delivery exhibited a greater attenuation (88 ± 15%) of intimal proliferation when compared to NO-ELIP (75 ± 13%) or R-ELIP (51 ± 6%) delivery alone. The study demonstrates the potential of echogenic liposomes as a promising platform for ultrasound imaging and therapeutic delivery.

PPARs and Their Neuroprotective Effects in Parkinson's Disease: A Novel Therapeutic Approach in α-Synucleinopathy?

Parkinson's disease (PD) is the most common α-synucleinopathy worldwide. The pathognomonic hallmark of PD is the misfolding and propagation of the α-synuclein (α-syn) protein, observed in post-mortem histopathology. It has been hypothesized that α-synucleinopathy triggers oxidative stress, mitochondrial dysfunction, neuroinflammation, and synaptic dysfunction, leading to neurodegeneration. To this date, there are no disease-modifying drugs that generate neuroprotection against these neuropathological events and especially against α-synucleinopathy. Growing evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists confer neuroprotective effects in PD, however, whether they also confer an anti-α-synucleinopathy effect is unknown. Here we analyze the reported therapeutic effects of PPARs, specifically the gamma isoform (PPARγ), in preclinical PD animal models and clinical trials for PD, and we suggest possible anti-α-synucleinopathy mechanisms acting downstream from these receptors. Elucidating the neuroprotective mechanisms of PPARs through preclinical models that mimic PD as closely as possible will facilitate the execution of better clinical trials for disease-modifying drugs in PD.

Effect of Flaxseed on TGF-Β, IL-6, and MMP9 Genes Expression during Wound Healing Process in Rabbits

BACKGROUND: Wound healing is a natural restorative response to tissue injury, and it involves regulated order of cellular and biochemical actions to reinstate tissue after injury, which involves resurfacing reconstitution, and restoration of tensile strength of injured skin. Normal and impaired wound healing post-significant problems related to healthcare and expenditure. Most of the chemical medications which widely used for wound healing might cause unwanted side effects with prolonged use such as hyper scarring, thus studies using natural products are now deemed important. Flaxseed is a natural product that enhances the immune system functioning against different diseases. Nevertheless, limited studies have been done looking into the response triggered by immune cells and the wound-healing-related genes with the use of flaxseed extract onto the wounded skin for the healing process. AIM: The main objective of this study is to analyze the expression of wound healing-related genes during different stages of the wound healing process induced by flaxseed in vivo. METHODS: The effect of flaxseed oil in the early stages (day 4 and 7) and late stages (day 14) of wound healing was explored on New Zealand white rabbits by creating a longitudinal full thickness wound on their back. The gene expression profiles of transforming growth factor-beta (TGF-β), IL-6, and metalloproteinase (MMP9) genes which have roles in wound healing through inflammation, proliferation, and remodeling were studied by polymerase chain reaction method. RESULTS: Flaxseed extract has significant effects in up-regulating anti-inflammatory marker TGF-β in wounds. Flaxseed oil also reduces the expression level of MMP9 on day 14 of wound healing. CONCLUSIONS: This suggests that flaxseed extract has the potential to promote wound healing through the regulation of TGF-β and MMP9 in vivo.

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.

Molecular evidence of the amelioration of toluene induced encephalopathy by human breast milk mesenchymal stem cells

Toluene was widely used volatile organic compound that accumulates in tissues with high lipid content. Stem cells have been proposed as an increasingly attractive approach for repair of damaged nervous system, we aimed to evaluate the ability of breast milk mesenchymal stem cells (MSc) to ameliorate toluene-induced encephalopathy. Sixty adult male albino rats were assigned to 3 groups, control, toluene, and toluene/breast milk-MSc. Neurological assessment was evaluated as well as serum levels of glial fibrillary acidic protein (GFAP), tumor necrosis factor-alpha (TNF-α), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), tissue dopamine and oxidative markers. Gene expression of peroxisome Proliferator-Activated Receptor-Gamma (PPAR-ɣ), nuclear factor-kappaB (NF-kB), and interleukin-6 (IL-6) were evaluated. Moreover, histological and immunohistochemical investigation were done. Results revealed that toluene caused cerebral injury, as evidenced by a significant increase in serum GFAP, TNF-α, malondialdehyde (MDA) and nitric oxide (NO), a significant decrease in serum NGF, tissue dopamine and oxidative markers, besides, a non-significant change in VEGF. Toluene also caused changes in normal cerebral structure and cellular degeneration, including a significant decrease in the total number of neurons and thickness of frontal cortex. Meninges showing signs of inflammation with inflammatory cell infiltration and exudation, a significant decrease in MBP immunoreactivity, and increase in the percent of high motility group box protein-1 (HMGB1) positive cells. PPAR- ɣ, NF-kB, and IL-6 gene expression were all considerably elevated by toluene. These changes were greatly improved by breast milk MSc. Therefore, we conclude that breast milk MSc can attenuate toluene-induced encephalopathy.

Identification of novel and potential PPARγ stimulators as repurposed drugs for MCAO associated brain degeneration

Peroxisome proliferator-activated receptor-gamma (PPARγ) has been shown to have therapeutic promise in the treatment of ischemic stroke and is supported by several studies. To identify possible PPARγ activators, the current study used an in silico technique in conjunction with molecular simulations and in vivo validation. FDA-approved drugs were evaluated using molecular docking to determine their affinity for PPARγ. The findings of molecular simulations support the repurposing of rabeprazole and ethambutol for the treatment of ischemic stroke. Adult Sprague Dawley rats were subjected to transient middle cerebral artery occlusion (t-MCAO). Five groups were made as a sham-operated, t-MCAO group, rabeprazole +t-MCAO, ethambutol +t-MCAO, and pioglitazone +t-MCAO. The neuroprotective effects of these drugs were evaluated using the neurological deficit score and the infarct area. The inflammatory mediators and signaling transduction proteins were quantified using Western blotting, ELISA, and immunohistochemistry. The repurposed drugs mitigated cerebral ischemic injury by PPARγ mediated downregulation of nods like receptor protein 3 inflammasomes (NLRP3), tumor necrosis factor-alpha (TNF-α), cyclooxygenase 2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-kB), and c-Jun N-terminal kinase (p-JNK). Our data demonstrated that rabeprazole and ethambutol have neuroprotective potential via modulating the cytoprotective stress response, increasing cellular survival, and balancing homeostatic processes, and so may be suitable for future research in stroke therapy.

Prediction of the endocrine-disrupting ability of 49 per- and polyfluoroalkyl substances: In silico and epidemiological evidence

The toxic effects of per- and polyfluoroalkyl substances (PFASs) on humans are mediated by nuclear hormone receptors (NHRs). However, data on the interaction of PFASs and NHRs is limited. Endocrine Disruptome, an inverse docking tool, was used in this study to simulate the docking of 49 common PFASs with 14 different types of human NHRs. According to the findings, 25 PFASs have a high or moderately high probability of binding to more than five NHRs, with androgen receptor (AR) and mineralocorticoid receptor (MR) being the most likely target NHRs. Molecular docking analyses revealed that the binding modes of PFASs with the two NHRs were similar to those of their corresponding co-crystallized ligands. PFASs, in particular, may disrupt the endocrine system by binding to MR. This finding is consistent with epidemiological research that has linked PFASs to MR-related diseases. Our findings may contribute to a better understanding of the health risks posed by PFASs.

Therapeutic implications of cyclooxygenase (COX) inhibitors in ischemic injury

INTRODUCTION

Ischemia-reperfusion injury (IRI) is the inexplicable aggravation of cellular dysfunction that results in blood flow restoration to previously ischemic tissues. COX mediates the oxidative conversion of AA to various prostaglandins and thromboxanes, which are involved in various physiological and pathological processes. In the pathophysiology of I/R injuries, COX has been found to play an important role. I/R injuries affect most vital organs and are characterized by inflammation, oxidative stress, cell death, and apoptosis, leading to morbidity and mortality.

MATERIALS AND METHODS

A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to understand the Nature and mechanistic interventions of the Cyclooxygenase modulations in ischemic injury. Here, we have discussed the COX Physiology and downstream signalling pathways modulated by COX, e.g., Camp Pathway, Peroxisome Proliferator-Activated Receptor Activity, NF-kB Signalling, PI3K/Akt Signalling in ischemic injury.

CONCLUSION

This review will discuss the various COX types, specifically COX-1 and COX-2, which are involved in developing I/R injury in organs such as the brain, spinal cord, heart, kidney, liver, and intestine.

Role of Phytoconstituents as PPAR Agonists: Implications for Neurodegenerative Disorders

Peroxisome proliferator-activated receptors (PPAR-γ, PPAR-α, and PPAR-β/δ) are ligand-dependent nuclear receptors that play a critical role in the regulation of hundreds of genes through their activation. Their expression and targeted activation play an important role in the treatment of a variety of diseases, including neurodegenerative, cardiovascular, diabetes, and cancer. In recent years, several reviews have been published describing the therapeutic potential of PPAR agonists (natural or synthetic) in the disorders listed above; however, no comprehensive report defining the role of naturally derived phytoconstituents as PPAR agonists targeting neurodegenerative diseases has been published. This review will focus on the role of phytoconstituents as PPAR agonists and the relevant preclinical studies and mechanistic insights into their neuroprotective effects. Exemplary research includes flavonoids, fatty acids, cannabinoids, curcumin, genistein, capsaicin, and piperine, all of which have been shown to be PPAR agonists either directly or indirectly. Additionally, a few studies have demonstrated the use of clinical samples in in vitro investigations. The role of the fruit fly Drosophila melanogaster as a potential model for studying neurodegenerative diseases has also been highlighted.

Pharmacological modulation of cytokines correlating neuroinflammatory cascades in epileptogenesis

Epileptic seizure-induced brain injuries include activation of neuroimmune response with activation of microglia, astrocytes cells releasing neurotoxic inflammatory mediators underlies the pathophysiology of epilepsy. A wide spectrum of neuroinflammatory pathways is involved in neurodegeneration along with elevated levels of inflammatory mediators indicating the neuroinflammation in the epileptic brain. Therefore, the neuroimmune response is commonly observed in the epileptic brain, indicating elevated cytokine levels, providing an understanding of the neuroinflammatory mechanism contributing to seizures recurrence. Clinical and experimental-based evidence suggested the elevated levels of cytokines responsible for neuronal excitation and blood-brain barrier (BBB) dysfunctioning causing the drug resistance in epilepsy. Therefore, the understanding of the pathogenesis of neuroinflammation in epilepsy, including migration of microglial cells releasing the inflammatory cytokines indicating the correlation of elevated levels of inflammatory mediators (interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) triggering the generation or recurrence of seizures. The current review summarized the knowledge regarding elevated inflammatory mediators as immunomodulatory response correlating multiple neuroinflammatory NF-kB, RIPK, MAPK, ERK, JNK, JAK-STAT signaling cascades in epileptogenesis. Further selective targeting of inflammatory mediators provides beneficial therapeutic strategies for epilepsy.

Repurposing Small Molecules to Target PPAR-γ as New Therapies for Peripheral Nerve Injuries

The slow rate of neuronal regeneration that follows peripheral nerve repair results in poor recovery, particularly where reinnervation of muscles is delayed, leading to atrophy and permanent loss of function. There is a clear clinical need to develop drug treatments that can accelerate nerve regeneration safely, restoring connections before the target tissues deteriorate irreversibly. The identification that the Rho/Rho-associated kinase (ROCK) pathway acts to limit neuronal growth rate is a promising advancement towards the development of drugs. Targeting Rho or ROCK directly can act to suppress the activity of this pathway; however, the pathway can also be modulated through the activation of upstream receptors; one of particular interest being peroxisome proliferator-activated receptor gamma (PPAR-γ). The connection between the PPAR-γ receptor and the Rho/ROCK pathway is the suppression of the conversion of inactive guanosine diphosphate (GDP)-Rho to active guanosine triphosphate GTP-Rho, resulting in the suppression of Rho/ROCK activity. PPAR-γ is known for its role in cellular metabolism that leads to cell growth and differentiation. However, more recently there has been a growing interest in targeting PPAR-γ in peripheral nerve injury (PNI). The localisation and expression of PPAR-γ in neural cells following a PNI has been reported and further in vitro and in vivo studies have shown that delivering PPAR-γ agonists following injury promotes nerve regeneration, leading to improvements in functional recovery. This review explores the potential of repurposing PPAR-γ agonists to treat PNI and their prospective translation to the clinic.