Emerging perspectives on precision therapy for Parkinson's disease: multidimensional evidence leading to a new breakthrough in personalized medicine.

PD is a prevalent and progressive neurodegenerative disorder characterized by both motor and non-motor symptoms. Genes play a significant role in the onset and progression of the disease. While the complexity and pleiotropy of gene expression networks have posed challenges for gene-targeted therapies, numerous pathways of gene variant expression show promise as therapeutic targets in preclinical studies, with some already in clinical trials. With the recognition of the numerous genes and complex pathways that can influence PD, it may be possible to take a novel approach to choose a treatment for the condition. This approach would be based on the symptoms, genomics, and underlying mechanisms of the disease. We discuss the utilization of emerging genetic and pathological knowledge of PD patients to categorize the disease into subgroups. Our long-term objective is to generate new insights for the therapeutic approach to the disease, aiming to delay and treat it more effectively, and ultimately reduce the burden on individuals and society.

Discovery of a Novel Orally Bioavailable FLT3-PROTAC Degrader for Efficient Treatment of Acute Myeloid Leukemia and Overcoming Resistance of FLT3 Inhibitors.

Fms-like tyrosine receptor kinase 3 (FLT3) proteolysis-targeting chimeras (PROTACs) represent a promising approach to eliminate the resistance of FLT3 inhibitors. However, due to the poor druggability of PROTACs, the development of orally bioavailable FLT3-PROTACs faces great challenges. Herein, a novel orally bioavailable FLT3-ITD degrader A20 with excellent pharmacokinetic properties was discovered through reasonable design. A20 selectively inhibited the proliferation of FLT3-ITD mutant acute myeloid leukemia (AML) cells and potently induced FLT3-ITD degradation through the ubiquitin-proteasome system. Notably, oral administration of A20 resulted in complete tumor regression on subcutaneous AML xenograft models. Furthermore, on systemic AML xenograft models, A20 could completely eliminate the CD45+CD33+ human leukemic cells in murine and significantly prolonged the survival time of mice. Most importantly, A20 exerted significantly improved antiproliferative activity against drug-resistant AML cells compared to existing FLT3 inhibitors. These findings suggested that A20 could serve as a promising drug candidate for relapsed or refractory AML.

Biomethane production and microbial strategies corresponding to high organic loading treatment for molasses wastewater in an upflow anaerobic filter reactor.

Molasses wastewater contains high levels of organic compounds, cations, and anions, causing operational problems for anaerobic biological treatment. In this study, an upflow anaerobic filter (UAF) reactor was employed to establish a high organic loading treatment system for molasses wastewater and further investigated the microbial community dynamics in response to this stressful operation. The biogas production increased with an increase in total organic carbon (TOC) loading rate from 1.0 to 14 g/L/day, and then it decreased with further TOC loading rate addition until 16 g/L/day. The UAF reactor achieved a maximum biogas production of 6800 mL/L/day with a TOC removal efficiency of 66.5% at a TOC loading rate of 14 g/L/day. Further microbial analyses revealed that both the bacterial and archaeal communities developed multiple strategies to maintain stable operation of the reactor at high organic loading (e.g., Proteiniphilum and Defluviitoga maintained high abundances throughout the operation; Tissierella temporarily dominated the bacterial community at TOC loading rates of 8.0 to 14 g/L/day; and multi-trophic Methanosarcina shifted as the dominant methanogen at the TOC loading rates of 8.0 to 16 g/L/day). This study presents insights into a high organic loading molasses wastewater treatment system and the microbial flexibility in methane fermentation in response to process disturbances.

The role of plasma cortisol in dementia, epilepsy, and multiple sclerosis: A Mendelian randomization study.

Background: Many clinical studies have shown a correlation between plasma cortisol and neurological disorders. This study explored the causal relationship between plasma cortisol and dementia, epilepsy and multiple sclerosis based on Mendelian randomization (MR) method. Methods: Data were taken from the summary statistics of a genome-wide association study, FinnGen consortium and United Kingdom Biobank. Dementia, epilepsy, and multiple sclerosis were used as outcomes, and genetic variants associated with plasma cortisol were used as instrumental variables. The main analysis was performed using the inverse variance weighted method, and the results were assessed according to the odds ratio (OR) and 95% confidence interval. Heterogeneity tests, pleiotropy tests, and leave-one-out method were conducted to evaluate the stability and accuracy of the results. Results: In two-sample MR analysis, the inverse variance weighted method showed that plasma cortisol was associated with Alzheimer's disease (AD) [odds ratio (95% confidence interval) = 0.99 (0.98-1.00), P = 0.025], vascular dementia (VaD) [odds ratio (95% confidence interval) = 2.02 (1.00-4.05), P = 0.049)], Parkinson's disease with dementia (PDD) [odds ratio (95% confidence interval) = 0.24 (0.07-0.82), P = 0.023] and epilepsy [odds ratio (95% confidence interval) = 2.00 (1.03-3.91), P = 0.042]. There were no statistically significant associations between plasma cortisol and dementia with Lewy bodies (DLB), frontotemporal dementia (FTD) and multiple sclerosis. Conclusion: This study demonstrates that plasma cortisol increase the incidence rates of epilepsy and VaD and decrease the incidence rates of AD and PDD. Monitoring plasma cortisol concentrations in clinical practice can help prevent diseases, such as AD, PDD, VaD and epilepsy.

Comparative efficacy and safety of antidepressant therapy for the agitation of dementia: A systematic review and network meta-analysis.

Background: Dementia is a clinical syndrome commonly seen in the elderly individuals. With the prevalence of dementia, the incidence of neuropsychiatric symptoms in dementia patients is increasing annually. Agitation, as one of the neuropsychiatric symptoms, has a serious impact on the quality of life of patients with dementia. Several antidepressant drugs have been shown to be effective for treating agitated behavior symptoms in patients with dementia, but there are no direct comparisons among those drugs. Therefore, we carried out a network meta-analysis (NMA) to examine the efficacy and safety of those antidepressant drugs. Methods: We searched eight databases (PubMed, Cochrane Library, Web of Science, Embase, Wanfang Database, China National Knowledge Infrastructure, VIP Database and China biomedical literature service) from their inception to 6 November 2022. Randomized controlled trials (RCTs) reporting the efficacy and safety of antidepressant drugs in treating agitated behavior symptoms in patients with dementia were included in our analysis. The quality assessment was carried out by two researchers individually and the analysis was based on the frequency method. Results: Twelve articles with 1,146 participants were included in our analysis. Based on the outcome of the agitation score, treatment with citalopram (standardized mean difference, SMD = -0.44, 95% confidence interval, 95% CI = -0.72 to -0.16) showed significant benefits over the placebo group. Treatment with trazodone (odds ratio, OR = 4.58, 95% CI = 1.12-18.69) was associated with a higher risk of total adverse events compared with a placebo treatment. Conclusion: Among the antidepressant drugs included in this study, treatment with citalopram was probably the only optimal intervention, when considering the improvement from baseline to the end of the intervention, and there was not a statistically significant difference in safety when compared with a placebo treatment. Systematic review registration: https://www.crd.york.ac.uk/prospero/#recordDetails, identifier: PROSPERO, CRD42022320932.

Effects of N-methyl-D-aspartate receptor knockdown and hypoxia/reoxygenation injury on the neuronal proteome and transcriptome.

Introduction: Brain tissue is extremely sensitive to hypoxia/reoxygenation (H/R) injury, which can easily cause irreversible damage to neurons. H/R injury can induce neuronal apoptosis through glutamate-mediated excitotoxicity. N-methyl-d-aspartate receptor (NMDAR) is one of the main receptors of excitatory glutamate, and blocking NMDAR protects brain tissue from ischemic and hypoxic injury. However, NMDAR hypofunction can also cause psychotic symptoms or cognitive impairment. There is still a lack of systematic research on the changes in the proteome and transcriptome in neuronal cells under conditions of NMDAR hypofunction and H/R injury. Methods: We compared the changes in the proteome, transcriptome and lncRNA expression levels in neurons after NMDAR knockdown and H/R by isobaric tags for relative and absolute quantitation (iTRAQ) and RNA sequencing (RNA-Seq). Results: The results showed that the proteins Rps9, Rpl18 and Rpl15 and the lncRNAs XLOC_161072 and XLOC_065271 were significantly downregulated after NMDAR knockdown but upregulated after H/R; in contrast, the mRNAs Bank1 and Pcp4l1 and the lncRNAs XLOC_159404 and XLOC_031922 were significantly upregulated after NMDAR knockdown but downregulated after H/R. Discussion: In this study, we demonstrated the characterization of protein, mRNA, and lncRNA expression profiles in neurons following NMDAR knockdown and H/R injury. These molecules are involved in multiple biological functions and signaling pathways, and their roles in neurons lacking NMDAR and subjected to H/R injury deserve further study. Additionally, we found that lncRNAs respond fastest to hypoxic stimulation and that Gapdh is not suitable as a reference protein for NMDAR-reduced neuron-related experiments.

Enriched environment remedies cognitive dysfunctions and synaptic plasticity through NMDAR-Ca2+-Activin A circuit in chronic cerebral hypoperfusion rats.

Chronic cerebral ischemia (CCI) is one of the critical factors in the occurrence and development of vascular cognitive impairment (VCI). Apoptosis of nerve cells and changes in synaptic activity after CCI are the key factors to induce VCI. Synaptic stimulation up-regulates intraneuronal Ca2+ level through N-methyl-D-aspartic acid receptor (NMDAR) via induction of the activity-regulated inhibitor of death (AID) expression to produce active-dependent neuroprotection. Moreover, the regulation of synaptic plasticity could improve cognition and learning ability. Activin A (ActA), an exocrine protein of AID, can promote NMDAR phosphorylation and participate in the regulation of synaptic plasticity. We previously found that exogenous ActA can improve the cognitive function of rats with chronic cerebral ischemia and enhance the oxygenated glucose deprivation of intracellular Ca2+ level. In addition to NMDAR, the Wnt pathway is critical in the positive regulation of LTP through activation or inhibition. It plays an essential role in synaptic transmission and activity-dependent synaptic plasticity. The enriched environment can increase ActA expression during CCI injury. We speculated that the NMDAR-Ca2+-ActA signal pathway has a loop-acting mode, and the environmental enrichment could improve chronic cerebral ischemia cognitive impairment via NMDAR-Ca2+-ActA, Wnt/ß-catenin pathway is involved in this process. For the hypothesis verification, this study intends to establish chronic cerebral hypoperfusion (CCH) rat model, explore the improvement effect of enriched environment on VCI, detect the changes in plasticity of synaptic morphology and investigate the regulatory mechanism NMDAR-Ca2+-ActA-Wnt/ß-catenin signaling loop, providing a therapeutic method for the treatment of CCH.

Current Knowledge Regarding the Interaction Between Oral Bone Metabolic Disorders and Diabetes Mellitus.

Diabetes mellitus, a major chronic disease affecting human health, has been increasing in prevalence in recent years. Diabetes mellitus can cause bone metabolic disorders in patients, leading to osteoporosis, a higher risk of traumatic fracture, and other bone diseases. Bone metabolic disorders in the oral cavity principally manifest as periodontitis, loss of alveolar bone, and failure of implant osseointegration. In recent years, numerous studies have shown that there is a complex interaction between bone metabolic disorders and diabetes mellitus. This paper reviews the adverse effects of diabetes on oral bone metabolism disorders such as alveolar osteoporosis and bone loss in patients with periodontitis, discusses the potential mechanisms of diabetic bone loss, and suggests potential ways to prevent and treat oral bone loss in patients with diabetes mellitus.

Association between ALDH2 rs671 polymorphism and risk of ischemic stroke: A protocol for systematic review and meta analysis.

In last decades, many scholars have studied the relationship between aldehyde dehydrogenase 2 (ALDH2) rs671 and ischemic stroke (IS), however, the results obtained from these studies were inconclusive. The purpose of this study was to investigate the association between rs671 and the risk of IS by systematically review.Two researchers independently screened relevant published literatures, derived data and estimated the risk of bias of the research in Pubmed, Embase, Ovid, China National Knowledge Infrastructure (CNKI), Cochrane Library and China Biomedical Literature Database throughout March 29, 2020. All statistical analyses were performed with the Stata 12.0 software. The data of the study was analyzed using fixed and random effects models. The results were expressed by odds ratio (OR) and 95% confidence interval (95%CI).A total of 10 articles were included this study. The total number of samples for all studies was 5265, including 2762 cases and 2503 controls. Statistical results indicated statistical differences between ALDH2 rs671 polymorphism and IS under dominant model (AA vs. AG + GG) and allelic model (A vs G), ORs (95% CI) were 1.66 (1.27-2.17) (P = .00) and 1.34 (1.05-1.71) (P = .02), respectively. But there was no statistical difference under recessive model (AA + AG vs GG), OR (95% CI) was 1.40 (0.99-1.97), P = .06.ALDH2 rs671 polymorphism was related to IS risk for Chinese population and the A allele of rs671 may be a risk factor of IS.

Diabetes and its Potential Impact on Head and Neck Oncogenesis.

In recent years, the incidence of diabetes mellitus and cancer has increased sharply; indeed, these have become the two most important diseases threatening health and survival. Head and neck (HN) tumors are the sixth most common malignancies in humans. Numerous studies have shown that there are many common risk factors for diabetes mellitus and HN squamous cell carcinoma, including advanced age, poor diet and lifestyle, and environmental factors. However, the mechanism linking the two diseases has not been identified. A number of studies have shown that diabetes affects the development, metastasis, and prognosis of HN cancer, potentially through the associated hyperglycemia, hyperinsulinemia and insulin resistance, or chronic inflammation. More recent studies show that metformin, the first-line drug for the treatment of type 2 diabetes, can significantly reduce the risk of HN tumor development and reduce mortality in diabetic patients. Here, we review recent progress in the study of the relationship between diabetes mellitus and HN carcinogenesis, and its potential mechanisms, in order to provide a scientific basis for the early diagnosis and effective treatment of these diseases.

Role of epigenetic in leukemia: From mechanism to therapy.

Epigenetic variations can play remarkable roles in different normal and abnormal situations. Such variations have been shown to have a direct role in the pathogenesis of various diseases either through inhibition of tumor suppressor genes or increasing the expression of oncogenes. Enzymes involving in epigenetic machinery are the main actors in tuning the epigenetic-based controls on gene expressions. Aberrant expression of these enzymes can trigger big chaos in the cellular gene expression networks and finally lead to cancer progression. This situation has been shown in different types of leukemia, where high or low levels of an epigenetic enzyme are partly or highly responsible for the involvement or progression of a disease. DNA hypermethylation, different histone modifications, and aberrant miRNA expressions are three main epigenetic variations, which have been shown to play a role in leukemia progression. Epigenetic based treatments now are considered as novel and effective therapies in order to decrease the abnormal epigenetic modifications in patient cells. Different epigenetic-based approaches have been developed and tested to inhibit or reverse the unusual expression of epigenetic agents in leukemia. Acute myeloid leukemia (AML), the most prevalent acute leukemia in adults, is anaggressive hematological malignancy arising in hematopoietic stem and progenitor cells. With the exception of a few specific AML subtypes, the mainstays of treatment have not significantly changed over the last 20 years, and are still based on standard cytotoxic chemotherapy. In this review, we will discuss the recent development of therapeutics specifically targeting these key epigenetic programs in AML, describe their mechanism of action and present their current clinical development. Finally, we will discuss the opportunities presented by epigenetically targeted therapy in AML and will highlight future challenges ahead for the AML community, to ensure that this novel therapeutics are optimally translated into clinical practice and result in clinical improvement for AML patients.

Vascular Risk Factors and Alzheimer's Disease: Blood-Brain Barrier Disruption, Metabolic Syndromes, and Molecular Links.

Alzheimer's disease (AD) is a neurodegenerative disorder, marked by cortical and hippocampal deposition of amyloid-ß (Aß) plaques and neurofibrillary tangles and cognitive impairment. Studies indicate a prominent link between cerebrovascular abnormalities and the onset and progression of AD, where blood-brain barrier (BBB) dysfunction and metabolic disorders play key risk factors. Pericyte degeneration, endothelial cell damage, astrocyte depolarization, diminished tight junction integrity, and basement membrane disarray trigger BBB damage. Subsequently, the altered expression of low-density lipoprotein receptor-related protein 1 and receptor for advanced glycation end products at the microvascular endothelial cells dysregulate Aß transport across the BBB. White matter lesions and microhemorrhages, dyslipidemia, altered brain insulin signaling, and insulin resistance contribute to tau and Aß pathogenesis, and oxidative stress, mitochondrial damage, inflammation, and hypoperfusion serve as mechanistic links between pathophysiological features of AD and ischemia. Deregulated calcium homeostasis, voltage gated calcium channel functioning, and protein kinase C signaling are also common mechanisms for both AD pathogenesis and cerebrovascular abnormalities. Additionally, APOE polymorphic alleles that characterize impaired cerebrovascular integrity function as primary genetic determinants of AD. Overall, the current review enlightens key vascular risk factors for AD and underscores pathophysiologic relationship between AD and vascular dysfunction.

Astroglial connexins and cognition: memory formation or deterioration?

Connexins are the membrane proteins that form high-conductance plasma membrane channels and are the important constituents of gap junctions and hemichannels. Among different types of connexins, connexin 43 is the most widely expressed and studied gap junction proteins in astrocytes. Due to the key involvement of astrocytes in memory impairment and abundant expression of connexins in astrocytes, astroglial connexins have been projected as key therapeutic targets for Alzheimer's disease. On the other hand, the role of connexin gap junctions and hemichannels in memory formation and consolidation has also been reported. Moreover, deletion of these proteins and loss of gap junction communication result in loss of short-term spatial memory. Accordingly, both memory formation and memory deteriorating functions of astrocytes-located connexins have been documented. Physiologically expressed connexins may be involved in the memory formation, while pathologically increased expression of connexins with consequent excessive activation of astrocytes may induce neuronal injury and cognitive decline. The present review describes the memory formation as well as memory deteriorating functions of astroglial connexins in memory disorders of different etiology with possible mechanisms.

Exosomal Circular RNA as a Biomarker Platform for the Early Diagnosis of Immune-Mediated Demyelinating Disease.

Exosomes can pass through the blood-brain barrier and are present in the cerebrospinal fluid (CSF). The components in exosomes, such as DNA, RNA, protein, and lipids, change greatly and are closely related to disease progression. Circular RNA (circRNA) is stable in structure and has a long half-life in exosomes without degradation. Therefore, circRNA is considered an ideal biomarker and can be used to monitor a variety of central nervous system diseases. This study aimed to investigate the expression profiles of exosomal circRNA (exo-circRNA) in CSF from patients with immune-mediated demyelinating diseases to identify suitable biomarkers for the early diagnosis of immune-mediated demyelinating diseases. circRNA expression levels in exosomes obtained from five CSF samples from immune-mediated demyelinating disease patients and five paired CSF control samples were analyzed using a hybridization array. Hierarchical clustering analysis showed that 5,095 exo-circRNAs were differentially expressed between patients with immune-mediated demyelinating diseases and paired control samples. Of these exo-circRNAs, 26 were identified as significantly differentially expressed in CSF exosomes from patients with immune-mediated demyelinating diseases (FC ≥1.5 and p ≤ 0.05). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the upregulation or activation of protein tyrosine phosphatase receptor type F (PTPRF) and RAD23 homolog B, nucleotide excision repair protein (RAD23B) may be associated with the occurrence and development of immune-mediated demyelinating diseases. Then, a competing endogenous RNA network was constructed and centered on the most upregulated/downregulated exo-circRNAs to predict their function in immune-mediated demyelinating diseases. In addition, reverse transcription quantitative polymerase chain reaction results stating that hsa_circ_0087862 and hsa_circ_0012077 were validated in an independent cohort of subjects. Canonical correlation analysis results indicated a potential connection between exosomal hsa_circ_0012077 expression level and immunoglobulin G levels in CSF. Finally, the receiver operating characteristic (ROC) curve showed that when hsa_circ_0087862 or hsa_circ_0012077 was employed alone for diagnosing immune-mediated demyelinating diseases, the diagnostic accuracy was 100%. In conclusion, based on this study, exosomal hsa_circ_0087862 and hsa_circ_0012077 in CSF could be used as suitable biomarkers for the diagnosis of immune-mediated demyelinating disease based on their expression levels. Moreover, the upregulation or activation of PTPRF and RAD23B was potentially associated with the occurrence and development of immune-mediated demyelinating diseases.

Resveratrol Activates Autophagy via the AKT/mTOR Signaling Pathway to Improve Cognitive Dysfunction in Rats With Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) is a main cause of vascular dementia and is also an etiological factor of neurological diseases and mental disorders. However, few treatments are available for CCH, and new medications are needed. In the present study, we employed a rat model of CCH that was based on bilateral common carotid artery occlusion and investigated the therapeutic effects of resveratrol and its detailed mechanism of action. We evaluated neurological deficit scores and performed the Morris water maze test, hematoxylin and eosin staining, TUNEL staining, enzyme-linked immunosorbent assays, and Western blot. Resveratrol reduced neurological deficit scores in CCH rats and reduced pathological damage in the frontal cortex and hippocampus. Resveratrol activated autophagy and inhibited the expression of AKT/mechanistic target of rapamycin (mTOR) signaling pathway-related proteins. Treatment with a phosphoinositide-3 kinase inhibitor reversed the protective effect of resveratrol. These findings suggest that resveratrol improves cognitive function in a rat model of CCH and reduces oxidative stress-induced neuronal damage in the frontal cortex and hippocampus by activating autophagy and inhibiting neuronal apoptosis. These effects may be regulated by the AKT/mTOR signaling pathway.

Knockdown of microRNA-17-5p Enhances the Neuroprotective Effect of Act A/Smads Signal Loop After Ischemic Injury.

Cerebral ischemic injury is a leading cause of human mortality and disability, seriously threatening human health in the world. Activin A (Act A), as a well-known neuroprotective factor, could alleviate ischemic brain injury mainly through Act A/Smads signaling. In our previous study, a noncanonical Act A/Smads signal loop with self-amplifying property was found, which strengthened the neuroprotective effect of Act A. However, this neuroprotective effect was limited due to the self-limiting behavior mediated by Smad anchor for receptor activation (SARA) protein. It was reported that microRNA-17-5p (miR-17-5p) could suppress the expression of SARA in esophageal squamous cell carcinoma. Thus we proposed that knockdown of miR-17-5p could strengthen the neuroprotective effect of Act A/Smads signal loop through SARA. To testify this hypothesis, oxygen-glucose deficiency (OGD) was introduced to highly differentiated rattus pheochromocytoma (PC12) cells. After the transfection of miR-17-5p mimic or inhibitor, the activity of Act A signal loop was quantified by the expression of phosphorylated Smad3. The results showed that suppression of miR-17-5p up-regulated the expression of SARA protein, which prolonged and strengthened the activity of Act A signaling through increased phosphorylation of downstream Smad3 and accumulation of Act A ligand. Further luciferase assay confirmed that SARA was a direct target gene of miR-17-5p. These practical discoveries will bring new insight on the endogenous neuroprotective effects of Act A signal loop by interfering a novel target: miR-17-5p.

Involvement of Endothelin-1, H2S and Nrf2 in Beneficial Effects of Remote Ischemic Preconditioning in Global Cerebral Ischemia-Induced Vascular Dementia in Mice.

The present study explored the role of endothelin-1, H2S, and Nrf2 in remote preconditioning (RIPC)-induced beneficial effects in ischemia-reperfusion (I/R)-induced vascular dementia. Mice were subjected to 20 min of global ischemia by occluding both carotid arteries to develop vascular dementia, which was assessed using Morris water maze test on 7th day. RIPC was given by subjecting hind limb to four cycles of ischemia (5 min) and reperfusion (5 min) and it significantly restored I/R-induced locomotor impairment, neurological severity score, cerebral infarction, apoptosis markers along with deficits in learning and memory. Biochemically, there was increase in the plasma levels of endothelin-1 along with increase in the brain levels of H2S and its biosynthetic enzymes viz., cystathionine-ß-synthase (CBS) and cystathionine-γ-lyase (CLS). There was also an increase in the expression of Nrf2 and glutathione reductase in the brain in response to RIPC. Pretreatment with bosentan (dual blocker of ETA and ETB receptors), amino-oxyacetic acid (CBS synthase inhibitor), and DL-propargylglycine (CLS inhibitor) significantly attenuated RIPC-mediated beneficial effects and biochemical alterations. The effects of bosentan on behavioral and biochemical parameters were more significant than individual treatments with CBS or CLS inhibitors. Moreover, CBS and CLS inhibitors did not alter the endothelin-1 levels possibly suggesting that endothelin-1 may act as upstream mediator of H2S. It is concluded that RIPC may stimulate the release endothelin-1, which may activate CBS and CLS to increase the levels of H2S and latter may increase the expression of Nrf2 to decrease oxidative stress and prevent vascular dementia.

Hyperpolarization-activated and cyclic nucleotide-gated channel proteins as emerging new targets in neuropathic pain.

Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are activated during hyperpolarization, and there is an inward flow of current, which is termed as hyperpolarization-activated current, Ih. Initially, these channels were identified on the pacemaker cells of the heart. Nowadays, these are identified on different regions of the nervous system, including peripheral nerves, dorsal root ganglia, dorsal horns, and different parts of the brain. There are four different types of HCN channels (HCN1-HCN4); however, HCN1 and HCN2 are more prominent. A large number of studies have shown that peripheral nerve injury increases the amplitude of Ih current in the neurons of the spinal cord and the brain. Moreover, there is an increase in the expression of HCN1 and HCN2 protein channels in peripheral axons and the spinal cord and brain regions in experimental models of nerve injury. Studies have also documented the pain-attenuating actions of selective HCN inhibitors, such as ivabradine and ZD7288. Moreover, certain drugs with additional HCN-blocking activities have also shown pain-attenuating actions in different pain models. There have been few studies documenting the relationship of HCN channels with other mediators of pain. Nevertheless, it may be proposed that the HCN channel activity is modulated by endogenous opioids and cyclo-oxygenase-2, whereas the activation of these channels may modulate the actions of substance P and the expression of spinal N-methyl-D-aspartate receptor subunit 2B to modulate pain. The present review describes the role and mechanisms of HCN ion channels in the development of neuropathic pain.

Role of hydrogen sulfide in cognitive deficits: Evidences and mechanisms.

Hydrogen sulfide (H2S) is a gaseous molecule and is endogenously produced in the brain by cystathionine beta-synthase, 3-mercaptopyruvate-sulfurtransferase, cysteine aminotransferase and cystathionine γ-lyase. Physiologically, H2S acts as a neuromodulator and regulates synaptic activity of neurons and glia to promote the development of long-term potentiation. A decrease in H2S levels in the brain and plasma has been directly correlated with the degree of severity of Alzheimer disease in patients. A large number of studies have shown a decrease in the H2S levels in experimental models of cognitive dysfunction and exogenous administration of sodium hydrosulfide (NaHS), a H2S donor, has been shown to prevent the development of memory deficits. The beneficial effects of H2S in different models has been ascribed to decrease in neuroinflammation, up-regulation of antioxidant defense, decrease in endoplasmic reticulum (ER) stress, inhibition of phosphatidylinositol 3-kinase (PI3-K)/Akt signaling, inhibition of mitogen activated protein (MAP) kinases, decrease in glutamate and normalization of NMDA receptors, inhibition of matrix metalloproteinases (MMPs), up-regulation of silent information regulator 1 (Sirt 1) and preservation of mitochondrial function. The present review describes the role of H2S in different models of cognitive deficits and human subjects along with possible mechanisms.