NMDA Receptor Activation Stimulates Hypoxia-Induced TRPM2 Channel Activation, Mitochondrial Oxidative Stress, and Apoptosis in Neuronal Cell Line: Modular Role of Memantine

Deciphering the Neuroprotective Action of Bee Venom Peptide Melittin: Insights into Mechanistic Interplay

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis, are characterized by progressive loss of neuronal structure and function. These conditions often lead to cognitive decline, motor dysfunction, and ultimately severe impairment of daily activities. A key feature of neurodegenerative diseases is chronic inflammation, which contributes to neuronal damage and exacerbates disease progression. Traditional treatments mainly focus on symptomatic relief rather than addressing the underlying causes, highlighting the need for novel therapeutic approaches. Melittin, a bioactive peptide derived from bee venom, has garnered attention for its multifaceted neuroprotective properties, particularly in the context of neuroinflammatory and neurodegenerative disorders. This review delves into the molecular mechanisms through which melittin exerts neuroprotective effects, with a focus on its ability to modulate neuroinflammation, apoptosis, and neurogenesis. Research indicates that melittin can downregulate pro-apoptotic pathways by inhibiting calpain-mediated activation of apoptosis-inducing factor and Bax, thereby reducing neuronal cell death. Additionally, melittin exerts its neuroprotective effects through the inhibition of neuroinflammatory processes, specifically by downregulating key inflammatory pathways such as NF-κB and MAPK. This modulation leads to decreased production of proinflammatory cytokines and prostaglandins, which are implicated in the pathogenesis of neurodegenerative disorders. Beyond its anti-inflammatory actions, melittin promotes neurogenesis, potentially through the modulation of the BDNF/Trk-B/CREB signaling pathway, which plays a crucial role in neuronal survival and plasticity. These properties suggest that melittin not only provides symptomatic relief but could also address the root causes of neuronal degeneration, presenting a promising avenue for the development of new treatments for neurodegenerative diseases. Further research is required to validate its efficacy and safety in clinical settings.

Expression of Neuronal Nicotinic Acetylcholine Receptor and Early Oxidative DNA Damage in Aging Rat Brain-The Effects of Memantine

Aging and age-related neurodegenerative disorders are characterized by the dysfunction or loss of brain nicotinic acetylcholine receptors (nAChRs), and these changes may be related to other senescence markers, such as oxidative stress and DNA repair dysfunction. However, the mechanism of nAChR loss in the aging brain and the modification of this process by drugs (e.g., memantine, Mem) are not yet fully understood. To study whether the differences in nAChR expression in the rat brain occur due to aging or oxidative stress and are modulated by Mem, we analyzed nAChR subunits (at RNA and protein levels) and other biomarkers by real-time quantitative polymerase chain reaction (RQ-PCR) and Western blot validation. Twenty-one female Wistar rats were divided into four groups, depending on age, and the oldest group received injections of Mem or water with the use of intragastric catheters. We studied the cerebral grey matter (CGM), subcortical white matter (SCWM), and cerebellum (Ce). Results showed an age-related decrease of α7 nAChR mRNA level in SCWM. The α7 nAChR mRNA loss was accompanied by reduced expression of 8-oxoguanine DNA glycosylase 1 (OGG1) and an increased tumor necrosis factor alpha (TNFα) level. In the water group, we observed a higher level of α7 nAChR protein in the SCWM and Ce. Biomarker levels changed, but to a different extent depending on the brain area. Importantly, the dysfunction in antioxidative status was stopped and even regressed under Mem treatment. After two weeks of treatment, an increase in TP53 protein level and a decrease in 8-oxo-2'deoxyguanosine (8-oxo-2'dG) level were observed. We conclude that Mem administration may be protective against the senescence process by antioxidative mechanisms.

Silica Nanoparticles Induce SH-SY5Y Cells Death Via PARP and Caspase Signaling Pathways

A growing stream of research indicates that exposure to Silica nanoparticles (SiNPs) can cause nervous system damage, leading to the occurrence of neurodegenerative diseases such as Alzheimer's disease. However, the specific mechanism by which SiNPs cause neuroblast injury remains unclear and requires further research. This study established an in vitro experimental model of SH-SY5Y cells exposed to SiNPs and observed cell growth through an inverted fluorescence microscope. Cell viability was measured using an MTT assay. The intracellular ROS and Ca2+ levels were detected by flow cytometry. Cell apoptosis was observed using both Hoechst33342 staining and TUNEL staining. The activities of SOD and ATPase and the content of ATP in the cells were tested by biochemical methods. The genes including parp-1, aif, par, ucp2, vdac and prdx3 were explored using quantitative real-time PCR. The expressions of PARP, AIF, PAR, Caspase-3, Caspase-9 and Cyt C proteins were evaluated by Western Blot. The immunofluorescence technique was used to observe the distribution of Parthanatos-related proteins induced by SiNPs. The results showed that SiNPs reduced cell survival rate, induced excessive ROS and Ca2+ overload, decreased SOD activity, ATPase activity, intracellular and mitochondrial ATP content, increased the expression of mitochondrial function and PARP pathway related genes, as well as PARP and Caspase pathway protein expression, ultimately inducing cell apoptosis. As a further test of the roles of PARP and Caspase pathways in SiNPs induced SH-SY5Y cells death, we selected the PARP inhibitor Olaparib and Caspase inhibitor Z-VAD, and the above effects were significantly improved after treatment with the inhibitors. Conclusively, this study confirmed that SiNPs can generate excessive ROS production in SH-SY5Y cells, alter mitochondrial function, and induce cell death through Parthanatos and caspase dependent apoptotic pathways, which can coexist and interact with each other.

The Effect of Selenium Against Cadmium-Induced Nephrotoxicity in Rats: The Role of the TRPM2 Channel

This study investigated the protective effect of selenium (Se) in a cadmium (Cd)-induced nephrotoxicity model in rats and the role of the TRPM2 channel in this mechanism. For this purpose, Cd (25 mg/kg orally), Se (0.5 mg/kg i.p.), and 2-aminoethoxydiphenyl borate (2-APB), a TRPM2 channel antagonist, (3 mg/kg i.p.) were administered to rats every day for 5 days. At the end of the study, kidney tissues were analysed using histological and biochemical methods. A histopathological examination revealed congestion, tubular degeneration, necrosis, and glomerular adhesion in the Cd group. However, these lesions were significantly reduced in the Cd + Se and Cd + 2-APB groups, while the Cd + Se + 2-APB group showed a histological appearance similar to the control group. Immunohistochemical analysis revealed that Caspase-3, Bax, and TRPM2 expression was higher in the Cd group, while these levels were lower in the Se and 2-APB treatment groups (p < 0.05). Among the groups that received Cd, urea, creatinine, TOS, TNF-α, and IL-1β levels were at the highest level in the Cd group, while TAS level was at the lowest level (p < 0.05). The Se and 2-APB treatment modulated these parameters; however, Se + 2-APB treatment reduced urea, creatinine, TOS, TNF-α, and IL-1β levels to the lowest level compared to the Cd groups and brought the TAS level closer to the control group (p < 0.05). These findings indicated that targeting TRPM2 channel inactivation together with the selenium treatment could alleviate Cd-induced nephrotoxicity.

The Role of TRPM2 Channel in Doxorubicin-induced Cell Damage in Laryngeal Squamous Cancer Cells

Laryngeal squamous cell carcinoma is a common type of head and neck cancer. This study investigated the role of the TRPM2 channel in doxorubicin (DOX)-induced cell damage in human laryngeal squamous cancer cells (Hep-2). Cells were exposed to various DOX concentrations and the appropriate dose was found. Then, TRPM2 antagonist ACA was treated. At the end of the study, cell viability test, Western blot and oxidative stress and inflammatory markers were examined. The results showed that TRPM2 channel expression increased with DOX administration, and DOX incubation in cells caused an increase in ROS, MDA, IL-1β, IL-6, and TNF-α levels, while GSH and GSH-Px levels decreased. Concurrent treatment with ACA attenuated these effects and reduced oxidative stress and inflammation. In addition, DOX-induced apoptosis markers including Casp-3, Casp-8, Casp-9, p53, and Bax were elevated, while Bcl-2 levels were decreased; ACA treatment reversed these changes. The study demonstrated that DOX treatment significantly enhances TRPM2 channel activation and ROS production in Hep-2 cells, thereby initiating apoptotic pathways that lead to cell death. Consequently, targeting the TRPM2 channel may represent a promising therapeutic strategy for treating laryngeal cancer.

Downregulation and inhibition of TRPM2 calcium channel prevent oxidative stress-induced endothelial dysfunction in the EA.hy926 endothelial cells model - Preliminary studies

PURPOSE

Proper functioning of the endothelial barrier is crucial for cardiovascular system homeostasis. Oxidative stress can lead to endothelial dysfunction (ED), damaging lipids, proteins, and DNA. Reactive oxygen species also increase cytoplasmic Ca2+ levels, activating transient receptor potential melastatin 2 (TRPM2), a membrane non-selective calcium channel. The study aimed to assess TRPM2's significance in vascular endothelial cells' response to oxidative stress and the potential use of TRPM2 direct and indirect inhibitors in the prevention of oxidative stress-induced ED.

MATERIALS AND METHODS

EA.hy926 endothelial cells were exposed to hydrogen peroxide for 24 ​h to mimic oxidative stress conditions. To assess the significance of TRPM2 in the response of EA.hy926 ​cells to hydrogen peroxide TRPM2 siRNA as well as direct (N-(p-Amylcinnamoyl)anthranilic acid, flufenamic acid) and indirect (3-aminobenzamide, 3,4-dihydro-5[4-(1-piperidinyl)butyl]-1(2H)-isoquinolinone) TRPM2 inhibitors were tested.

RESULTS

Results showed that hydrogen peroxide-induced ED is alleviated by TRPM2 downregulation. Moreover, preincubation of cells with both direct and indirect TRPM2 inhibitors for 30 ​min before hydrogen peroxide treatment reduces its negative effects on cell viability, cell migration, and junctional proteins.

CONCLUSIONS

The obtained results suggest that TRPM2 channel may be a potential target in therapy and prevention of cardiovascular diseases connected with oxidative stress-induced ED. However, further research is needed for clinical applications of direct and indirect TRPM2 inhibitors.

S32, a Novel 3-Acetylaminocoumarin Compound, Exerts Neuroprotective Effects through the Inhibition of Neuroinflammation and Oxidative Stress In Vitro and In Vivo

Neuroinflammation and oxidative stress are key factors leading to neuronal injury. In this study, we investigated the role of S32, a novel 3-acetylaminocoumarin compound, in ameliorating neuronal injury induced by neuroinflammation and oxidative stress in vitro and in vivo. First, we found that S32 reduced the expression levels of p-P65 and p-P38, inhibited the nuclear translocation of P65, and lowered the levels of pro-inflammatory factors in LPS-induced BV2 cells, which indicated that S32 had an antineuroinflammatory effect. Second, BV2 cell culture medium was used as the conditioned medium to establish a model of oxidative damage in PC12 cells. It was found that S32 reduced the level of ROS and increased mitochondrial membrane potential of PC12 cells, which indicated that S32 can protect PC12 cells against conditioned medium-induced injury. Next, we found that S32 inhibited the decrease of cell viability of PC12 cells caused by H2O2, inhibited nuclear damage, decreased the level of ROS, increased MMP, activated the AKT and ERK pathways, increased Bcl-2 levels, and decreased Bax and Cleaved-Caspase3 expression levels, indicating that S32 ameliorated the damaging effects of H2O2-induced PC12 cells. Finally, we found that S32 exerted the antineuroinflammatory and apoptosis-inhibiting effects in LPS-induced mice. In conclusion, this study first demonstrated that S32, a novel 3-acetylaminocoumarin compound, can reduce neuroinflammation and neuroinflammation-induced neuronal injury, exerting an indirect protective effect on neurons, and also exert a direct protective effect on neurons by reducing oxidative stress.

Simultaneous use of venlafaxine and calcium channel blockers on tolerance to morphine: The role of mitochondrial damage and oxidative stress in the brain

BACKGROUND

One of the reasons for tolerance to morphine is increased oxidative stress and dysfunction of cell mitochondria in the hippocampus. Venlafaxine and calcium channel blockers can protect mitochondrial function. The investigation of the role of mitochondrial damage and oxidative stress in the simultaneous use of venlafaxine and calcium channel blockers on the acute analgesic effects of morphine and the induction of tolerance to its effects in mice was assessed.

METHOD

In this experimental study, to induce tolerance to morphine, NMRI mice were treated with 50 mg/kg morphine for three consecutive days and 5 mg/kg morphine on the fourth day. Venlafaxine (20 mg/kg) alone or in combination with calcium channel blockers, nimodipine (10 mg/kg), and diltiazem (40 mg/kg) was administered 30 min before morphine, and the hot plate test was used. Then, hippocampal mitochondria were isolated by differential centrifugation method, and the levels of mitochondrial dehydrogenase activity, mitochondrial membrane potential, mitochondrial ROS production rate, as well as the content of glutathione and malondialdehyde in hippocampal mitochondria, were measured.

RESULTS

The administration of venlafaxine-nimodipine and venlafaxine-diltiazem increased morphine's acute analgesic effects (P < 0.05) and reduced the induction and expression of tolerance to the analgesic effects of morphine (P < 0.05). Morphine significantly decreased MTT and GSH and increased MDA, mitochondrial membrane damage, and ROS compared to the control group (P < 0.01). Injection of venlafaxine-nimodipine and also venlafaxine-diltiazem 30 min before morphine can improve these alterations (P < 0.05).

DISCUSSION AND CONCLUSION

Our data showed that the simultaneous use of venlafaxine with calcium channel blockers could increase the acute analgesic effects of morphine and reduce the induction and expression of tolerance to it. Also, the preventive and protective roles of simultaneous administration of venlafaxine and calcium channel blockers on morphine-induced mitochondrial oxidative stress and damage during the tolerance test were achieved.

Kynurenic acid protects against ischemia/reperfusion injury by modulating apoptosis in cardiomyocytes

Acute myocardial infarction, often associated with ischemia/reperfusion injury (I/R), is a leading cause of death worldwide. Although the endogenous tryptophan metabolite kynurenic acid (KYNA) has been shown to exert protection against I/R injury, its mechanism of action at the cellular and molecular level is not well understood yet. Therefore, we examined the potential involvement of antiapoptotic mechanisms, as well as N-methyl-D-aspartate (NMDA) receptor modulation in the protective effect of KYNA in cardiac cells exposed to simulated I/R (SI/R). KYNA was shown to attenuate cell death induced by SI/R dose-dependently in H9c2 cells or primary rat cardiomyocytes. Analysis of morphological and molecular markers of apoptosis (i.e., membrane blebbing, apoptotic nuclear morphology, DNA double-strand breaks, activation of caspases) revealed considerably increased apoptotic activity in cardiac cells undergoing SI/R. The investigated apoptotic markers were substantially improved by treatment with the cytoprotective dose of KYNA. Although cardiac cells were shown to express NMDA receptors, another NMDA antagonist structurally different from KYNA was unable to protect against SI/R-induced cell death. Our findings provide evidence that the protective effect of KYNA against SI/R-induced cardiac cell injury involves antiapoptotic mechanisms, that seem to evoke independently of NMDA receptor signaling.

Cerebral Hypoxia-Induced Molecular Alterations and Their Impact on the Physiology of Neurons and Dendritic Spines: A Comprehensive Review

This article comprehensively reviews how cerebral hypoxia impacts the physiological state of neurons and dendritic spines through a series of molecular changes, and explores the causal relationship between these changes and neuronal functional impairment. As a severe pathological condition, cerebral hypoxia can significantly alter the morphology and function of neurons and dendritic spines. Specifically, dendritic spines, being the critical structures for neurons to receive information, undergo changes such as a reduction in number and morphological abnormalities under hypoxic conditions. These alterations further affect synaptic function, leading to neurotransmission disorders. This article delves into the roles of molecular pathways like MAPK, AMPA receptors, NMDA receptors, and BDNF in the hypoxia-induced changes in neurons and dendritic spines, and outlines current treatment strategies. Neurons are particularly sensitive to cerebral hypoxia, with their apical dendrites being vulnerable to damage, thereby affecting cognitive function. Additionally, astrocytes and microglia play an indispensable role in protecting neuronal and synaptic structures, regulating their normal functions, and contributing to the repair process following injury. These studies not only contribute to understanding the pathogenesis of related neurological diseases but also provide important insights for developing novel therapeutic strategies. Future research should further focus on the dynamic changes in neurons and dendritic spines under hypoxic conditions and their intrinsic connections with cognitive function.

The effects of berberine and curcumin on cardiac, lipid profile and fibrosis markers in cyclophosphamide-induced cardiac damage: The role of the TRPM2 channel

Cyclophosphamide (CYP) is widely used to treat various types of cancer. In addition to the therapeutic properties of this drug, unfortunately, its side effects are still not fully understood. This study investigated the protective effect of curcumin (CURC) and berberine (BER) on CYP-induced cardiac damage. Thirty-six male rats were equally divided into the control, dimethyl sulfoxide (DMSO), CYP, CYP + CURC, CYP + BER and CYP + BER + CURC groups. Troponin-I, Creatine kinase-myocardial band (CK-MB), total cholesterol, triglyceride levels in serum samples, and reactive oxygen species (ROS), poly(ADP-ribose) polymerase-1 (PARP-1), and transient receptor potential melastatin 2 (TRPM2) channel levels in heart tissue were measured using an enzyme-linked immunoassay (ELISA) kit. In addition, histopathological examination and immunohistochemical investigation of the TRPM2 channel, fibroblast specific protein-1 (FSP1), transforming growth factor-beta- 1 (TGF-β1) and α-smooth muscle actin (α-SMA) expressions were determined in heart tissue. The CYP group's troponin-I, total cholesterol, triglyceride, CK-MB, ROS, PARP-1 and TRPM2 channel levels were higher than in the other groups in the ELISA measurements (p < 0.05). In contrast, these parameters in the group treated with CURC and BER together with CYP were lower than in the CYP group (p < 0.05). Additionally, CUR and BER reduced CYP-induced pathological damage, TRPM2, FSP1, TGF-β1 and α-SMA expressions. The data showed that CYP administration can cause cardiac damage by increasing the TRPM2 channel, TGF-β1, FSP1 and α-SMA expression levels. Therefore, we concluded that CURC and BER administration following CYP application may be used as therapeutic agents to prevent CYP-induced cardiac damage.

Investigating the impact of Psidium guajava leaf hydroalcoholic extract in improving glutamatergic toxicity-induced oxidative stress in Danio rerio larvae

Glutamate is one of the predominant excitatory neurotransmitters released from the central nervous system; however, at high concentrations, this substance may induce excitotoxicity. This phenomenon is involved in numerous neuropathologies. At present, clinically available pharmacotherapeutic agents to counteract glutamatergic excitotoxicity are not completely effective; therefore, research to develop novel compounds is necessary. In this study, the main objective was to determine the pharmacotherapeutic potential of the hydroalcoholic extract of Psidium guajava (PG) in a model of oxidative stress-induced by exposure to glutamate utilizing Danio rerio larvae (zebrafish) as a model. Data showed that treatment with glutamate produced a significant increase in oxidative stress, chromatin damage, apoptosis, and locomotor dysfunction. All these effects were attenuated by pre-treatment with the classical antioxidant N-acetylcysteine (NAC). Treatment with PG inhibited oxidative stress responsible for cellular damage induced by glutamate. However, exposure to PG failed to prevent glutamate-initiated locomotor damage. Our findings suggest that under conditions of oxidative stress, PG can be considered as a promising candidate for treatment of glutamatergic excitotoxicity and consequent neurodegenerative diseases.

FGF13 enhances the function of TRPV1 by stabilizing microtubules and regulates acute and chronic itch

Itching is an aversive somatosensation that triggers the desire to scratch. Transient receptor potential (TRP) channel proteins are key players in acute and chronic itch. However, whether the modulatory effect of fibroblast growth factor 13 (FGF13) on acute and chronic itch is associated with TRP channel proteins is unclear. Here, we demonstrated that conditional knockout of Fgf13 in dorsal root ganglion neurons induced significant impairment in scratching behaviors in response to acute histamine-dependent and chronic dry skin itch models. Furthermore, FGF13 selectively regulated the function of the TRPV1, but not the TRPA1 channel on Ca2+ imaging and electrophysiological recordings, as demonstrated by a significant reduction in neuronal excitability and current density induced by TRPV1 channel activation, whereas TRPA1 channel activation had no effect. Changes in channel currents were also verified in HEK cell lines. Subsequently, we observed that selective modulation of TRPV1 by FGF13 required its microtubule-stabilizing effect. Furthermore, in FGF13 knockout mice, only the overexpression of FGF13 with a tubulin-binding domain could rescue TRP channel function and the impaired itch behavior. Our findings reveal a novel mechanism by which FGF13 is involved in TRPV1-dependent itch transduction and provide valuable clues for alleviating pathological itch syndrome.

24S-Hydroxycholesterol in Neuropsychiatric Diseases: Schizophrenia, Autism Spectrum Disorder, and Bipolar Disorder

Neuropsychiatric diseases (NPDs) are severe, debilitating psychiatric conditions that affect the nervous system. These are among the most challenging disorders in medicine. Some examples include Alzheimer's, anxiety disorders, autism spectrum disorder, bipolar disorder, and schizophrenia. NPDs represent an ever-increasing burden on public health and are prevalent throughout the world. For most of these diseases, the particular etiopathogeneses are still enigmatic. NPDs are also associated with structural and functional changes in the brain, along with altered neurotransmitter and neuroendocrine systems.Approximately 25% of the total human body cholesterol is located in the brain. Its involvement in neuronal functions starts in the early growth stages and remains important throughout adulthood. It is also an integral part of the neuronal membrane, ensuring membrane lipid organization and regulating membrane fluidity. The main mechanism for removing cholesterol from the brain is cholesterol 24-hydroxylation by cytochrome P450 46A1 (CYP46A1), an enzyme specifically found in the central nervous system. Although research on 24S-OHC and its role in neuropsychiatric diseases is still in its early stages, this oxidized cholesterol metabolite is thought to play a crucial role in the etiology of NPDs. 24S-OHC can affect neurons, astrocytes, oligodendrocytes, and vascular cells. In addition to regulating the homeostasis of cholesterol in the brain, this oxysterol is involved in neurotransmission, oxidative stress, and inflammation. The role of 24S-OHC in NPDs has been found to be controversial in terms of the findings so far. There are several intriguing discrepancies in the data gathered so far regarding 24S-OHC and NPDs. In fact, 24S-OHC levels were reported to have decreased in a number of NPDs and increased in others.Hence, in this chapter, we first summarize the available data regarding 24S-OHC as a biomarker in NPDs, including schizophrenia, autism spectrum disorder, and bipolar disorder. Then, we present a brief synopsis of the pharmacological targeting of 24S-OHC levels through the modulation of CYP46A1 activity.

Extrasynaptic NMDA receptors in acute and chronic excitotoxicity: implications for preventive treatments of ischemic stroke and late-onset Alzheimer's disease

Stroke and late-onset Alzheimer's disease (AD) are risk factors for each other; the comorbidity of these brain disorders in aging individuals represents a significant challenge in basic research and clinical practice. The similarities and differences between stroke and AD in terms of pathogenesis and pathophysiology, however, have rarely been comparably reviewed. Here, we discuss the research background and recent progresses that are important and informative for the comorbidity of stroke and late-onset AD and related dementia (ADRD). Glutamatergic NMDA receptor (NMDAR) activity and NMDAR-mediated Ca²⁺ influx are essential for neuronal function and cell survival. An ischemic insult, however, can cause rapid increases in glutamate concentration and excessive activation of NMDARs, leading to swift Ca²⁺ overload in neuronal cells and acute excitotoxicity within hours and days. On the other hand, mild upregulation of NMDAR activity, commonly seen in AD animal models and patients, is not immediately cytotoxic. Sustained NMDAR hyperactivity and Ca²⁺ dysregulation lasting from months to years, nevertheless, can be pathogenic for slowly evolving events, i.e. degenerative excitotoxicity, in the development of AD/ADRD. Specifically, Ca²⁺ influx mediated by extrasynaptic NMDARs (eNMDARs) and a downstream pathway mediated by transient receptor potential cation channel subfamily M member (TRPM) are primarily responsible for excitotoxicity. On the other hand, the NMDAR subunit GluN3A plays a "gatekeeper" role in NMDAR activity and a neuroprotective role against both acute and chronic excitotoxicity. Thus, ischemic stroke and AD share an NMDAR- and Ca²⁺-mediated pathogenic mechanism that provides a common receptor target for preventive and possibly disease-modifying therapies. Memantine (MEM) preferentially blocks eNMDARs and was approved by the Federal Drug Administration (FDA) for symptomatic treatment of moderate-to-severe AD with variable efficacy. According to the pathogenic role of eNMDARs, it is conceivable that MEM and other eNMDAR antagonists should be administered much earlier, preferably during the presymptomatic phases of AD/ADRD. This anti-AD treatment could simultaneously serve as a preconditioning strategy against stroke that attacks ≥ 50% of AD patients. Future research on the regulation of NMDARs, enduring control of eNMDARs, Ca²⁺ homeostasis, and downstream events will provide a promising opportunity to understand and treat the comorbidity of AD/ADRD and stroke.

TRPM2-mediated Ca2+ signaling as a potential therapeutic target in cancer treatment: an updated review of its role in survival and proliferation of cancer cells

The transient receptor potential melastatin subfamily member 2 (TRPM2), a thermo and reactive oxygen species (ROS) sensitive Ca²⁺-permeable cation channel has a vital role in surviving the cell as well as defending the adaptability of various cell groups during and after oxidative stress. It shows higher expression in several cancers involving breast, pancreatic, prostate, melanoma, leukemia, and neuroblastoma, indicating it raises the survivability of cancerous cells. In various cancers including gastric cancers, and neuroblastoma, TRPM2 is known to conserve viability, and several underlying mechanisms of action have been proposed. Transcription factors are thought to activate TRPM2 channels, which is essential for cell proliferation and survival. In normal physiological conditions with an optimal expression of TRPM2, mitochondrial ROS is produced in optimal amounts while regulation of antioxidant expression is carried on. Depletion of TRPM2 overexpression or activity has been shown to improve ischemia-reperfusion injury in organ levels, reduce tumor growth and/or viability of various malignant cancers like breast, gastric, pancreatic, prostate, head and neck cancers, melanoma, neuroblastoma, T-cell and acute myelogenous leukemia. This updated and comprehensive review also analyzes the mechanisms by which TRPM2-mediated Ca²⁺ signaling can regulate the growth and survival of different types of cancer cells. Based on the discussion of the available data, it can be concluded that TRPM2 may be a unique therapeutic target in the treatment of several types of cancer. Video Abstract.