Psychiatric Disorders and TRP Channels: Focus on Psychotropic Drugs

Lavender essential oil alleviates depressive-like behavior in alcohol-withdrawn rats: Insights from gut metabolites and hippocampal transcriptome analysis

Lavender, an aromatic plant with a history dating back to ancient Egypt and Greece, is consumed because of its diverse pharmacological properties, including sedation, sleep aid, and antidepressant effects. However, the mechanisms underlying these antidepressant properties remain unclear. In this study, we explored the impact of lavender essential oil (LEO) inhalation on the diversity of gut microbiota, metabolites, and differential gene expression in the hippocampus of alcohol-withdrawn depressive rats. Additionally, we examined alterations in the hippocampal transient receptor potential (TRP) channel-mediated inflammatory regulation within the brain-gut axis of depressive rats. The results demonstrated a significant decrease in sucrose preference, diminished activity in the central zone of the open field test, and prolonged immobility time in the forced swim test in alcohol-withdrawn depressive rats, indicating the amelioration of depressive states following lavender essential oil inhalation. 16 S rDNA sequencing analysis revealed a significant reduction in Bacteroidota and Muribaculaceae in the gut of alcohol-withdrawn depressive rats, whereas lavender essential oil significantly increased the relative abundance of Muribaculaceae and other bacterial species. Metabolomic analysis identified 646 distinct metabolites as highly correlated biomarkers between the model and lavender essential oil groups. Furthermore, lavender essential oil inhalation significantly attenuated hippocampal inflammatory factors IL-2, IL-6, IL-1β, and TNF-α. This study identified elevated expression of Trpv4 and Calml4 in the hippocampal region of alcohol-withdrawn depressed rats and showed that lavender essential oil inhalation regulated aberrantly expressed genes. Our research suggests that lavender essential oil downregulates Trpv4, modulates inflammatory factors, and alleviates depressive-like behavior in alcohol withdrawal rats.

Serum exosomal microRNAs as potential biomarkers for centrally mediated abdominal pain syndrome

Centrally mediated abdominal pain syndrome (CAPS) has generated a heavy disease burden worldwide. This study aimed to explore the serum exosomal microRNAs as potential diagnostic biomarkers for CAPS. From September 2022 to October 2023, 97 patients with CAPS and 96 healthy subjects were enrolled. Differentially expressed serum exosomal miRNAs between patients with CAPS and healthy controls were identified by high-throughput sequencing and quantitative real-time polymerase chain reaction (qRT-PCR). The Receiver Operating Characteristic (ROC) curves and multivariate logistic regression analysis were used to evaluate the diagnostic value of the serum exosomal miRNAs. MiR-6850-5p, miR-194-5p, miR-199a-3p, miR-4525 which were significantly downregulated in serum exomes of CAPS patients compared to healthy controls which yielded the AUC values of 0.914 (95% CI, 0.873-0.954), 0.767 (95% CI, 0.695-0.839), 0.617 (95% CI, 0.527-0.708) and 0.561 (95% CI, 0.465-0.656), respectively to distinguish CAPS patients from healthy subjects. And AUC of the integration of the above 4 miRNAs was 0.931 (95% CI, 0.896-0.966). Multivariate logistic regression indicated that hsa-miR-6850-5p (OR=0.046; p<0.001), anxiety (OR=7.670; p=0.025) and depression (OR=22.967; p=0.008) were the independent predictors of CAPS. Serum exosomal miR-6850-5p is a promising diagnostic biomarker for CAPS. PERSPECTIVE: This study may be the first to explore serum exosomal miRNAs as a new diagnostic biomarker for CAPS, and the findings may help clinicians to access comprehensive understanding and accurate diagnosis of CAPS.

Non-electrophysiological techniques targeting transient receptor potential (TRP) gene of gastrointestinal tract

Transient receptor potential (TRP) channels are cation channels related to a wide range of physical and chemical stimuli, they are expressed all along the gastrointestinal system, and a myriad of diseases are often associated with aberrant expression or mutation of the TRP gene, suggesting that TRPs are promising targets for drug therapy. Therefore, a better understanding of the information of TRPs in health and disease could facilitate the development of effective drugs for the treatment of gastrointestinal diseases like IBD. But there are very few generalizations about the experimental techniques studied in this field. In view of the promise of TRP as a therapeutic target, we discuss experimental methods that can be used for TRPs including their distribution, function and interaction with other proteins, as well as some promising emerging technologies to provide experimental methods for future studies.

Seasonality of presentation and birth in catatonia

BACKGROUND

Catatonia is a neuropsychiatric syndrome associated with both psychiatric disorders and medical conditions. Understanding of the pathophysiology of catatonia remains limited, and the role of the environment is unclear. Although seasonal variations have been shown for many of the disorders underlying catatonia, the seasonality of this syndrome has not yet been adequately explored.

METHODS

Clinical records were screened to identify a cohort of patients suffering from catatonia and a control group of psychiatric inpatients, from 2007 to 2016 in South London. In a cohort study, the seasonality of presentation was explored fitting regression models with harmonic terms, while the effect of season of birth on subsequent development of catatonia was analyzed using regression models for count data. In a case-control study, the association between month of birth and catatonia was studied fitting logistic regression models.

RESULTS

In total, 955 patients suffering from catatonia and 23,409 controls were included. The number of catatonic episodes increased during winter, with a peak in February. Similarly, an increasing number of cases was observed during summer, with a second peak in August. However, no evidence for an association between month of birth and catatonia was found.

CONCLUSIONS

The presentation of catatonia showed seasonal variation in accordance with patterns described for many of the disorders underlying catatonia, such as mood disorders and infections. We found no evidence for an association between season of birth and risk of developing catatonia. This may imply that recent triggers may underpin catatonia, rather than distal events.

Transient Receptor Potential (TRP) Channels in Pain, Neuropsychiatric Disorders, and Epilepsy

Pharmacomodulation of membrane channels is an essential topic in the study of physiological conditions and disease status. Transient receptor potential (TRP) channels are one such family of nonselective cation channels that have an important influence. In mammals, TRP channels consist of seven subfamilies with a total of twenty-eight members. Evidence shows that TRP channels mediate cation transduction in neuronal signaling, but the full implication and potential therapeutic applications of this are not entirely clear. In this review, we aim to highlight several TRP channels which have been shown to mediate pain sensation, neuropsychiatric disorders, and epilepsy. Recent findings suggest that TRPM (melastatin), TRPV (vanilloid), and TRPC (canonical) are of particular relevance to these phenomena. The research reviewed in this paper validates these TRP channels as potential targets of future clinical treatment and offers patients hope for more effective care.

The Association between Spicy Food Consumption and Psychological Health in Chinese College Students: A Cross-Sectional Study

BACKGROUND

Capsaicin is the main active ingredient in chili peppers and spicy food. Animal studies provide contradictory results on the role of capsaicin in psychiatric disorders. There are no epidemiological studies to investigate the relationship between spicy food consumption and psychological health.

METHODS

A cross-sectional online survey was conducted. Psychological health was assessed with the Depression Anxiety Stress Scale, and spicy food consumption was assessed as frequency, strength, and duration of consumption. Multivariable logistic regression was conducted to determine the associations between spicy food consumption and psychological symptoms.

RESULTS

Our sample comprised 1771 participants (male = 674, mean age = 21.97 years). The odds of having depressive, anxiety, and stress symptoms were 34.0%, 46.5%, and 19.1% in Chinese college students, respectively. After adjusting for a series of covariates, compared with non-consumers, the odds ratios (ORs) of depressive symptoms across spicy food consumption were 1.13 (95% CI: 0.87-1.46) for 1-2 days/week and 1.38 (95% CI: 1.02-1.86) for ≥3 days/week. With regard to anxiety symptoms, the ORs were 0.99 (95% CI: 0.78, 1.27) for 1-2 days/week and 1.50 (95% CI: 1.13-1.99) for ≥3 days/week. For stress symptoms, the ORs were 0.90 (95% CI: 0.66-1.23) for 1-2 days/week and 1.27 (95% CI: 0.89-1.80) for ≥3 days/week. The ORs for the depressive symptoms associated with different intensities of spicy food consumption were 1.00 (reference) for the reference group (non-consumers), 1.17 (95% CI: 0.90-1.52) for eating weakly spicy food, and 1.34 (95% CI: 1.01-1.78) for moderately to strongly spicy food.

CONCLUSION

The findings suggested a positive association between frequently spicy food consumption and depressive/anxiety symptoms in adolescents, and no such association was found for stress symptoms.

Protective role of selenium on MPP+ and homocysteine-induced TRPM2 channel activation in SH-SY5Y cells

Homocysteine is an intermediate product of biochemical reactions occurring in living organisms. It is known that drugs that increase dopamine synthesis used in Parkinson's disease (PD) cause an increase in the plasma homocysteine level. As the plasma homocysteine level increases, the amount of intracellular free calcium ion ([Ca²⁺]_i) and oxidative stress increase. As a result, it contributes to the excitotoxic effect by causing neurodegeneration. TRPM2 cation channel is activated by high [Ca²⁺]_i and oxidative stress. The role of TRPM2 in the development of neuronal damage due to the increase in homocysteine in PD has not yet been elucidated. In current study, we aimed to investigate the role of the TRPM2 and selenium (Se) in SH-SY5Y neuronal cells treated with homocysteine (HCT) and MPP . SH-SY5Y cells were divided into four groups: control, MPP, MPP + HCT, and MPP + HCT + Se. The results of plate reader assay, confocal microscope imaging, and western blot analyses indicated upregulation of apoptosis, [Ca²⁺]_i, mitochondrial membrane depolarization, caspase activation, and intracellular ROS values in the cells. The MPP + HCT group had considerably higher values than the other groups. The MPP + HCT + Se group had significantly lower values than all the other groups except the control group. In addition, incubation of MPP + HCT and MPP + HCT + Se groups with TRPM2 antagonist 2-APB increased cell viability and reduced intracellular calcium influx and apoptosis levels. It is concluded that the activation of TRPM2 was propagated in HCT and MPP-induced SH-SY5Y cells by the increase of oxidative stress. The antioxidant property of Se regulated the TRPM2 channel activation and neurodegeneration by providing intracellular oxidant/antioxidant balance.

Hydroxychloroquine Attenuates Acute Inflammation (LPS)-Induced Apoptosis via Inhibiting TRPV1 Channel/ROS Signaling Pathways in Human Monocytes

Simple Summary

LPS is a well-known agent in cell line models, including U937 monocytes, for inducing acute inflammation (INF). It is not known whether antioxidant HCQ, through the inhibition of TRPV1 in U937, can decrease oxidative monocyte toxicity and cell death. We investigated the modulator action of HCQ treatment through the modulation of TRPV1 on the levels of mROS, INF, and apoptosis in an LPS-stimulated U937 monocyte model. Acute INF activates apoptotic, inflammatory, and oxidant action through acute INF-dependent excessive cROS, MDA, cytokine generation, and Ca²⁺ influx in U937 human monocyte cells. Furthermore, treatment with acute INF increases TRPV1 and apoptotic marker (CAS3, CAS9, Bax, and Bcl-2) concentrations via downregulation of glutathione level and glutathione peroxidase activity in U937 monocytes. The acute INF-caused U937 oxidative stress and cytotoxicity is diminished by the treatment of HCQ and TRPV1 inhibitor (CPZ). In summary, treatment with HCQ and CPZ induced anti-inflammatory, anti-apoptotic, and antioxidant action via the inhibition of cROS, cytokine generation, and caspase activation.

Abstract

Acute inflammation (INF) and apoptosis are induced in monocytes by the generation of several factors, including the products of cytosolic oxygen free radicals (cROS) and the excessive influx of Ca²⁺ via the stimulation of TRPV1. These are main factors in the etiology of monocyte activation-induced inflammatory and neurodegenerative diseases. Importantly, the protective action of hydroxychloroquine (HCQ) treatment via the inhibition of TRPV1 on the levels of inflammatory factors, cROS, and apoptosis in acute INF (lipopolysaccharide, LPS)-exposed neuronal cells was recently reported. However, the relationships between acute INF via TRPV1 activation and HCQ in monocytes have not been fully clarified yet. The cell membrane of U937 human monocytes contains natural TRPV1. In the study plan, we used U937 cells in four main groups, namely control, HCQ (60 μM for 48 h), INF (1 μg/mL LPS for 16 h), and HCQ + INF. The current data indicate that LPS-induced acute INF caused the upregulation of excessive cytosolic Ca²⁺ accumulation via the stimulation of TRPV1 in the cells. The treatment of INF additionally upregulated the levels of apoptosis and cytokines (IL6, IL1β, and TNFα), due to upregulated cROS and lipid peroxidation levels as well as upregulated generation of caspase -3 (CAS3) and -9 (CAS9) but a decrease in glutathione and glutathione peroxidase. The expression levels of TRPV1, Bax, CAS3, and CAS9 were also upregulated by the treatment of LPS. However, treatment with HCQ and TRPV1 blocker (capsazepine) modulated the levels of cytokines, caspases, cROS, Ca²⁺ influx, and apoptosis through the modulation of TRPV1 in the U937 that were stimulated with LPS. In summary, the present data suggest TRPV1 activation through the acute INF (LPS)-induced inflammatory, oxidant, and apoptotic adverse actions in monocyte cells, whereas HCQ prevented adverse actions via the modulation of TRPV1. The results may be significant in the modulation of monocyte activation-caused inflammatory and neurodegenerative diseases.

Role of TRPV1 channels on glycogen synthase kinase-3β and oxidative stress in ouabain-induced bipolar disease

Bipolar disorder (BD) is a multifactorial chronic and refractory disease characterized by manic, depressive, and mixed mood episodes. Although epidemiological, and pathophysiological studies demonstrated a strong correlation between bipolar disorder and oxidative stress, precise etiology is still missing. Recent studies suggested the possible role of transient receptor potential channels (TRP) in the BD but, current knowledge is limited. Therefore, the current study investigates the possible role of TRPV1 in the ouabain-induced model of BD. The model was created with intracerebroventricular single dose ouabain (10^-3 M) administration. Animals were treated with capsaicin, capsazepine, and lithium for seven days. Mania and depressive-like states were investigated with open-field, sucrose preference, and elevated plus maze tests. Oxidative stress was assessed by measuring total antioxidant and oxidant states, spectrophotometrically. The phosphorylation Glycogen synthase kinase-3β (GSK-3β) evaluated by western blotting. Our results demonstrated that capsaicin dose-dependently inhibited the ouabain-induced hyperlocomotion and depression. Although capsazepine exacerbated behavioral impairment, it did not show a significant effect on the antioxidant and oxidant states, and the effects of capsazepine on behaviors were abolished by combination with capsaicin. Additionally, capsaicin potently prevented the ouabain-induced decrease in GSK-3β phosphorylation. In contrast, capsazepine potentiated ouabain-induced decrease in GSK-3β phosphorylation and combination with capsaicin, suppressed the effect of capsazepine on GSK-3β phosphorylation. The effects of TRPV1 activation on oxidative stress and mania-like behaviors in the ouabain-induced BD model might be regulated by GSK-3β phosphorylation.

Interferon Gamma-Mediated Oxidative Stress Induces Apoptosis, Neuroinflammation, Zinc Ion Influx, and TRPM2 Channel Activation in Neuronal Cell Line: Modulator Role of Curcumin

Host defenses in the brain are modulated by the activation of several factors such as oxygen free radical species (ROS), Ca²⁺ influx, and TRPM2 activation, and they are well-known adverse factors in neurotoxicity and neurodegenerative diseases. Importantly, recent data indicated a protective action of curcumin (CRC) via inhibition of TRPM2 on the inflammation factors, ROS, and apoptosis in hypoxia-induced SH-SY5Y neuronal cells. However, the relationship between interferon gamma (IFNg) exposure and TRPM2 activation in the SH-SY5Y cells are not fully identified. The SH-SY5Y cells as a neuronal cell line model were used in several neuroinflammation studies. Hence, we used the SH-SY5Y cells in the current study, and they were divided into four main groups as control, CRC, IFNg, and IFNg+CRC. The data presented here indicate that IFNg induced excessive Ca²⁺ influx via activation of TRPM2. The IFNg treatment further increased cell death, cell debris amount, apoptosis, and cytokine generations (IL-1β, IL-6, and TNF-α) which were due to increased cytosolic and mitochondrial ROS generations as well as increased activations of caspase-3 and caspase-9. The expression levels of TRPM2, PARP-1, Bax, caspase-3, and caspase-9 were increased in the cells by the IFNg treatment. However, CRC treatment reduced the increase of expression levels, cytokine generations, caspase activations, ROS release, Ca²⁺ influx, cell death, and apoptosis levels via inhibition of TRPM2 in the SH-SY5Y cells that were treated with IFNg. Moreover, the treatment of TRPM2 blockers (ACA and 2-APB) potentiated the modulator effects of CRC. In conclusion, these results suggest that neuroinflammation via IFNg lead to the TRPM2 activation in the SH-SY5Y cells, whereas CRC prevents IFNg-mediated TRPM2 activation, cell death, and cytokine generations.

Environmental pharmaceuticals and climate change: The case study of carbamazepine in M. galloprovincialis under ocean acidification scenario

Contaminants of emerging concern and ocean changes are key environmental stressors for marine species with possibly synergistic, but still unexplored, deleterious effects. In the present study the influence of a simulated ocean acidification scenario (pH = 7.6) was investigated on metabolism and sub-lethal effects of carbamazepine, CBZ (1 µg/L), chosen as one of the most widely diffused pharmaceuticals in marine organisms. A multidisciplinary approach was applied on mussels, M. galloprovincialis, integrating measurement of drug bioaccumulation with changes in the whole transcriptome, responsiveness of various biochemical and cellular biomarkers including immunological parameters, lipid and oxidative metabolism, onset of genotoxic effects. Chemical analyses revealed a limited influence of hypercapnia on accumulation and excretion of CBZ, while a complex network of biological responses was observed in gene expression profile and functional changes at cellular level. The modulation of gamma-aminobutyric acid (GABA) pathway suggested similarities with the Mechanism of Action known for vertebrates: immune responses, cellular homeostasis and oxidative system represented the processes targeted by combined stressors. The overall elaboration of results through a quantitative Weight of Evidence model, revealed clearly increased cellular hazard due to interactions of CBZ with acidification compared to single stressors.

Multiscale neurobiological correlates of human neuroticism

Neuroticism is a heritable personality trait associated with negative emotionality; however, we know little regarding the association between the microscale and macroscale neurobiological substrates of human neuroticism. Cross‐scale correlation analysis may provide such information. In this study, voxel‐wise neuroimaging–neuroticism correlation analyses consistently showed a positive correlation between neuroticism and functional connectivity density (FCD) in the ventral striatum in 274 young Chinese adults. Partial least squares regression analysis showed that the FCD‐neuroticism correlation map was significantly spatially correlated with gene expression profiles in each of six donated human brains. Neuroticism‐related genes derived from the six donors consistently showed significant enrichment in the chemical synaptic transmission, circadian entrainment, long‐term potentiation, inflammatory mediator regulation of transient receptor potential channels, and amphetamine addiction pathways. The protein–protein interaction analysis revealed four hub genes involved in the above pathways, including G protein subunit gamma 10, 5‐hydroxytryptamine receptor 2C, prodynorphin, and calcium/calmodulin‐dependent protein kinase II alpha. By combining multiscale correlation analyses and functional annotations, this study advances our understanding of the genetic and neural substrates of human neuroticism and emphasizes the importance of striatal functional properties in human neuroticism.

Amelioration of diabetes-induced cognitive impairment by Transient Receptor Potential Vanilloid 2 (TRPV2) channel inhibitor: Behavioral and mechanistic study

Transient receptor potential (TRP) channels are Ca²⁺ permeable non-selective cation channels which play a pivotal role in diabetes and diabetic complications. Among diabetic complications, diabetes-induced cognitive impairment is a major CNS complication. The role of several TRP channels has been investigated extensively for their diverse Ca²⁺ regulating mechanism, and recently their role has been postulated in the progression of neurodegenerative disorders. However, the role of TRPV2 has not been investigated yet. Therefore, in the present study, the involvement of TRPV2 channels was investigated in diabetes-induced cognitive impairment using TRPV2 inhibitor, tranilast. High glucose exposure in rat C6 glial cells enhances the Ca²⁺-entry through TRPV2 channels. In our in-vivo study, diabetic rats showed increased gene and protein expression of TRPV2 in the hippocampus. Subsequent increase in the acetylcholinesterase activity in the cortex, as well as decrease in the phosphorylation of Ca²⁺/calmodulin-dependent protein kinase II (p-CaMKII-Thr-286), p-GSK-3β (Ser-9), p-CREB (Ser-133) and postsynaptic density protein 95 (PSD-95) in the hippocampus were also observed this led to the impairment in the learning and memory as evident from behavioral parameters such as Morris water maze test, passive avoidance and Y-maze test paradigm. Three-week treatment with tranilast (30 and 100 mg/kg, p.o.) showed improvement in learning and memory associated behaviours (Morris water maze test, passive avoidance, and Y-maze test) by increasing the p-CaMKII (Thr-286), p-GSK-3β (Ser-9), p-CREB (Ser-133) and PSD-95 in the hippocampus. Cortical acetylcholinesterase activity was also reduced by the tranilast. These findings depicted that TRPV2 inhibition may be an effective treatment strategy in diabetes-induced cognitive deficits.

Therapeutic potential of pharmacological agents targeting TRP channels in CNS disorders

Central nervous system (CNS) disorders like Alzheimer's disease (AD), Parkinson disease (PD), stroke, epilepsy, depression, and bipolar disorder have a high impact on both medical and social problems due to the surge in their prevalence. All of these neuronal disorders share some common etiologies including disruption of Ca²⁺ homeostasis and accumulation of misfolded proteins. These misfolded proteins further disrupt the intracellular Ca²⁺ homeostasis by disrupting the activity of several ion channels including transient receptor potential (TRP) channels. TRP channel families include non-selective Ca²⁺ permeable channels, which act as cellular sensors activated by various physio-chemical stimuli, exogenous, and endogenous ligands responsible for maintaining the intracellular Ca²⁺ homeostasis. TRP channels are abundantly expressed in the neuronal cells and disturbance in their activity leads to various neuronal diseases. Under the pathological conditions when the activity of TRP channels is perturbed, there is a disruption of the neuronal homeostasis through increased inflammatory response, generation of reactive oxygen species, and mitochondrial dysfunction. Therefore, there is a potential of pharmacological interventions targeting TRP channels in CNS disorders. This review focuses on the role of TRP channels in neurological diseases; also, we have highlighted the current insights into the pharmacological modulators targeting TRP channels.

Morphine Induces Apoptosis, Inflammation, and Mitochondrial Oxidative Stress via Activation of TRPM2 Channel and Nitric Oxide Signaling Pathways in the Hippocampus

Morphine as an opioid is an important drug in the treatment of moderate to severe pain. Several stress factors via generation of nitric oxide (NO) and oxidative stress (OS) are responsible for the adverse effects of morphine-induced analgesia, addiction, and antinociceptive tolerance, including altered Ca²⁺ concentration, inflammation, OS, and release of apoptotic factors. TRPM2 is a Ca²⁺-permeable cation channel and it is activated by OS and NO. Hence, adverse effect of morphine addiction may occur via the OS and NO-induced TRPM2 activation. Because of the unclear etiology of morphine-induced adverse effects in the hippocampus, investigating the involvement of TRPM2 and NO synthetase (NOS) activations in the treatment of morphine-induced OS, apoptosis, and neuroinflammation is a major challenge. The hippocampal neuron of TRPM2 wild-type (TRPM2-WT) and knockout (TRPM2-KO) mice were divided into control, morphine, NOS inhibitor (L-NAME) + morphine, and TRPM2 channel blockers (ACA and 2-APB) + morphine. The morphine-induced increases of apoptosis, neuron death, OS, lipid peroxidation, caspase-3 and caspase-9, neuroinflammatory cytokines (IL-1β, TNF-α, IL-6), and Ca²⁺ levels in the hippocampal neuron of TRPM2-WT mouse were decreased by the L-NAME, ACA, and 2-APB treatments, although cell viability, neuron count, and reduced glutathione and glutathione peroxidase levels were increased by the treatments. However, the effects of morphine were not observed in the hippocampus of TRPM2-KO mice. Taken together, our data show that neurodegeneration adverse effects of morphine were induced by activation of TRPM2, and excessive generations of NO and OS. Thus, inhibition of TRPM2 may modulate morphine-induced neurodegeneration in the hippocampus.

Resveratrol diminishes bisphenol A-induced oxidative stress through TRPM2 channel in the mouse kidney cortical collecting duct cells

Bisphenol A (BisPH-A) is a latent danger that threatens our health, which we frequently exposure in our modern life (e.g. the widespread use of drinking water in plastic pet bottles). But the BisPH-A induced transient receptor potential melastatin 2 (TRPM2)-mediated oxidative stress and apoptosis in these cells has not been studied yet. Calcium (Ca²⁺) plays an important role in a versatile intracellular signal transduction that works over a wide range to regulate oxidative stress processes. TRPM2 is activated by oxidative stress and it has emerged as an important Ca²⁺ signaling mechanism in a variety of cells, contributing many cellular functions including cell death. Resveratrol (RESV), which belongs to the polyphenol group, acts as an antioxidant, eliminating cellular oxidative stress and increasing the body's resistance to diseases. The current study aimed to elucidate the effect of antioxidant resveratrol on TRPM2-mediated oxidative stress induced by BisPH-A exposure in the mouse kidney cortical collecting duct cells (mpkCCD_cl4). The cells were divided into four groups as control, resveratrol (50 µM for 24 h), BisPH-A (100 µM for 24 h) and BisPH-A + RESV. Intracellular free Ca²⁺ concentrations and TRPM2 channel currents were high in BisPH-A treated cells, but decreased with resveratrol treatment. In addition, BisPH-A induced mitochondrial membrane depolarization, reactive oxygen species (ROS), caspase 3, caspase 9 and apoptosis values were decreased by the resveratrol treatment. In conclusion, resveratrol protected cells from BisPH-A induced oxidative damage. In this study, we showed that TRPM2 channel mediates this protective effect of resveratrol.

Elevation of Transient Receptor Potential Vanilloid 1 Function in the Lateral Habenula Mediates Aversive Behaviors in Alcohol-withdrawn Rats

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

Chronic alcohol use and withdrawal leads to increased pain perception, anxiety, and depression. These aberrant behaviors are accompanied by increased excitatory glutamatergic transmission to, and activity of, the lateral habenula neurons.Vanilloid type 1, or TRPV1, channels are expressed in the habenula and they facilitate glutamatergic transmission. Whether TRPV1 channel plays a role in habenula hyperactivity is not clear.

WHAT THIS ARTICLE TELLS US THAT IS NEW

Glutamatergic transmission in the lateral habenula was inhibited by TRPV1 channel antagonists. In vivo, local administration of TRPV1 antagonists into the lateral habenula attenuated hyperalgesia, anxiety, and relapse-like drinking in rats who chronically consumed alcohol.The data suggest that enhanced TRPV1 channel function during withdrawal may contribute to aberrant behavior that promotes relapse alcohol consumption.

BACKGROUND

Recent rat studies indicate that alcohol withdrawal can trigger a negative emotional state including anxiety- and depression-like behaviors and hyperalgesia, as well as elevated glutamatergic transmission and activity in lateral habenula neurons. TRPV1, a vanilloid receptor expressed in the habenula, is involved in pain, alcohol dependence, and glutamatergic transmission. The authors therefore hypothesized that TRPV1 contributes to the changes in both the behavioral phenotypes and the habenula activity in alcohol-withdrawn rats.

METHODS

Adult male Long-Evans rats (n = 110 and 280 for electrophysiology and behaviors, respectively), randomly assigned into the alcohol and water (Naïve) groups, were trained to consume either alcohol or water-only using an intermittent-access procedure. Slice electrophysiology was used to measure spontaneous excitatory postsynaptic currents and firing of lateral habenula neurons. The primary outcome was the change in alcohol-related behaviors and lateral habenula activity induced by pharmacologic manipulation of TRPV1 activity.

RESULTS

The basal frequency of spontaneous excitatory postsynaptic currents and firing of lateral habenula neurons in alcohol-withdrawn rats was significantly increased. The TRPV1 antagonist capsazepine (10 µM) induced a stronger inhibition on spontaneous excitatory postsynaptic currents (mean ± SD; by 26.1 ± 27.9% [n = 11] vs. 6.7 ± 18.6% [n = 17], P = 0.027) and firing (by 23.4 ± 17.6% [n = 9] vs. 11.9 ± 16.3% [n = 12], P = 0.025) in Withdrawn rats than Naive rats. By contrast, the TRPV1 agonist capsaicin (3 μM) produced a weaker potentiation in Withdrawn than Naïve rats (spontaneous excitatory postsynaptic currents: by 203.6 ± 124.7% [n = 20] vs. 415.2 ± 424.3% [n = 15], P < 0.001; firing: 38.1 ± 14.7% [n = 11] vs. 73.9 ± 41.9% [n = 11], P < 0.001). Conversely, capsaicin's actions in Naïve but not in Withdrawn rats were significantly attenuated by the pretreatment of TRPV1 endogenous agonist N-Oleoyldopamine. In Withdrawn rats, intra-habenula infusion of TRPV1 antagonists attenuated hyperalgesia and anxiety-like behaviors, decreased alcohol consumption upon resuming drinking, and elicited a conditioned place preference.

CONCLUSIONS

Enhanced TRPV1 function may contribute to increased glutamatergic transmission and activity of lateral habenula neurons, resulting in the aberrant behaviors during ethanol withdrawal.

Effects of TRPV1 Activation by Capsaicin and Endogenous N-Arachidonoyl Taurine on Synaptic Transmission in the Prefrontal Cortex

While the transient receptor potential vanilloid 1 (TRPV1) ion channel, a non-selective calcium-permeable cation channel with high Ca²⁺ permeability, mainly integrates physical and chemical stimuli for nociception, recent studies suggest that it has a role beyond a noxious thermal sensor. In fact, TRPV1 is presently being considered as a target for treating pathophysiological processes including pain, fear, and anxiety disorders. Although this ion channel has many potential roles, its underlying mechanism of action remains elusive. Here we show in mice that activation of TRPV1-, by the exogenous agonist capsaicin-, regulates synaptic activity in both glutamatergic and GABAergic synaptic transmission. Moreover, activation by the endogenous activator N-arachidonoyl taurine (NAT), induced similar effects as capsaicin. On the other hand, taurine, the decomposition product of NAT, strongly depressed the evoked glutamatergic synaptic transmission. In addition to these findings, we also show the immunohistochemical distribution of TRPV1 in the prefrontal cortex (PFC) of mice, as such studies are currently less frequent in the PFC. Overall, these observations allow for a better understanding of how TRPV1 helps regulate excitatory and inhibitory synaptic activity in the PFC of mice.

Personalized Epigenome Remodeling Under Biochemical and Psychological Changes During Long-Term Isolation Environment

It has been reported that several aspects of human health could be disturbed during a long-term isolated environment (for instance, the Mars-500 mission), including psychiatric disorders, circadian disruption, temporal dynamics of gut microbiota, immune responses, and physical-activity-related neuromuscular performance. Nevertheless, the mechanisms underlying these disturbances and the interactions among different aspects of human adaptation to extreme environments remain to be elucidated. Epigenetic features, like DNA methylation, might be a linking mechanism that explains the involvement of environmental factors between the human genome and the outcome of health. We conducted an exploration of personalized longitudinal DNA methylation patterns of the peripheral whole blood cells, profiling six subjects across six sampling points in the Mars-500 mission. Specifically, we developed a Personalized Epigenetic-Phenotype Synchronization Analysis (PeSa) algorithm to explore glucose- and mood-state-synchronized DNA methylation sites, focusing on finding the dynamic associations between epigenetic patterns and phenotypes in each individual, and exploring the underling epigenetic connections between glucose and mood-state disturbance. Results showed that DMPs (differentially methylated-probes) were significantly enriched in pathways related to glucose metabolism (Type II diabetes mellitus pathway), mood state (Long-term depression) and circadian rhythm (Circadian entrainment pathway) during the mission. Furthermore, our data revealed individualized glucose-synchronized and mood-state-synchronized DNA methylation sites, and PTPRN2 was found to be associated with both glucose and mood state disturbances across all six subjects. Our findings suggest that personalized phenotype-synchronized epigenetic features could reflect the effects on the human body, including the disturbances of glucose and mood-states. The association analysis of DNA methylation and phenotypes, like the PeSa analysis, could provide new possibilities in understanding the intrinsic relationship between phenotypic changes of the human body adapting to long-term isolation environmental factors.

Cryo-EM structure of TRPC5 at 2.8-Å resolution reveals unique and conserved structural elements essential for channel function

The transient receptor potential canonical subfamily member 5 (TRPC5), one of seven mammalian TRPC members, is a nonselective calcium-permeant cation channel. TRPC5 is of considerable interest as a drug target in the treatment of progressive kidney disease, depression, and anxiety. Here, we present the 2.8-Å resolution cryo-electron microscopy (cryo-EM) structure of the mouse TRPC5 (mTRPC5) homotetramer. Comparison of the TRPC5 structure to previously determined structures of other TRPC and TRP channels reveals differences in the extracellular pore domain and in the length of the S3 helix. The disulfide bond at the extracellular side of the pore and a preceding small loop are essential elements for its proper function. This high-resolution structure of mTRPC5, combined with electrophysiology and mutagenesis, provides insight into the lipid modulation and gating mechanisms of the TRPC family of ion channels.

The role of convergent ion channel pathways in microglial phenotypes: a systematic review of the implications for neurological and psychiatric disorders

Increases in the activated state of microglia, the main neuroimmune cells, are widely reported in the brains of patients with neurological and psychiatric disorders. Microglia transform from the resting to the activated state by sensing their environment, aided by a variety of ion channels. To examine the effect of ion channels on microglial phenotypes, we conducted a systematic review of immunohistochemical analyses of these neuroimmune cells in animal models following administration of ion channel antagonists, compared to control conditions. A systematic search of the PubMed and Web of Science electronic databases using the PRISMA and WHO methodologies for systematic reviews yielded 15 original peer-reviewed studies. The majority (13 out of 15) of these studies reported a decrease in microglial activated state after ion signaling pharmacological blockade. The studies provide evidence that acute administration of ion channel antagonists leads to a reduction in microglial activation in rodent brains in the models for epilepsy, Parkinson's disease, inflammation, pain, ischemia, and brain and spinal cord injury. Future research should explore microglial-specific druggable targets for neurological and psychiatric disorders. The investigation of acute and chronic administration of ion channel antagonists in microglial phenotypes in primates and the development of microglia-like cells derived from human stem cells could be valuable sources in this direction.

Mechanisms and Therapeutic Targets of Depression After Intracerebral Hemorrhage

The relationship between depression and intracerebral hemorrhage (ICH) is complicated. One of the most common neuropsychiatric comorbidities of hemorrhagic stroke is Post-ICH depression. Depression, as a neuropsychiatric symptom, also negatively impacts the outcome of ICH by enhancing morbidity, disability, and mortality. However, the ICH outcome can be improved by antidepressants such as the frequently-used selective serotonin reuptake inhibitors. This review therefore presents the mechanisms of post-ICH depression, we grouped the mechanisms according to inflammation, oxidative stress (OS), apoptosis and autophagy, and explained them through their several associated signaling pathways. Inflammation is mainly related to Toll-like receptors (TLRs), the NF-kB mediated signal pathway, the PPAR-γ-dependent pathway, as well as other signaling pathways. OS is associated to nuclear factor erythroid-2 related factor 2 (Nrf2), the PI3K/Akt pathway and the MAPK/P38 pathway. Moreover, autophagy is associated with the mTOR signaling cascade and the NF-kB mediated signal pathway, while apoptosis is correlated with the death receptor-mediated apoptosis pathway, mitochondrial apoptosis pathway, caspase-independent pathways and others. Furthermore, we found that neuroinflammation, oxidative stress, autophagy, and apoptosis experience interactions with one another. Additionally, it may provide several potential therapeutic targets for patients that might suffer from depression after ICH.

Accumulation of minor alleles and risk prediction in schizophrenia

Schizophrenia is a common neuropsychiatric disorder with a lifetime risk of 1%. Accumulation of common polygenic variations has been found to be an important risk factor. Recent studies showed a role for the enrichment of minor alleles (MAs) of SNPs in complex diseases such as Parkinson’s disease. Here we similarly studied the role of genome wide MAs in schizophrenia using public datasets. Relative to matched controls, schizophrenia cases showed higher average values in minor allele content (MAC) or the average amount of MAs per subject. By risk prediction analysis based on weighted genetic risk score (wGRS) of MAs, we identified an optimal MA set consisting of 23 238 variants that could be used to predict 3.14% of schizophrenia cases, which is comparable to using 22q11 deletion to detect schizophrenia cases. Pathway enrichment analysis of these SNPs identified 30 pathways with false discovery rate (FDR) <0.02 and of significant P-value, most of which are known to be linked with schizophrenia and other neurological disorders. These results suggest that MAs accumulation may be a risk factor to schizophrenia and provide a method to genetically screen for this disease.

Cannabinoids and Vanilloids in Schizophrenia: Neurophysiological Evidence and Directions for Basic Research

Much of our knowledge of the endocannabinoid system in schizophrenia comes from behavioral measures in rodents, like prepulse inhibition of the acoustic startle and open-field locomotion, which are commonly used along with neurochemical approaches or drug challenge designs. Such methods continue to map fundamental mechanisms of sensorimotor gating, hyperlocomotion, social interaction, and underlying monoaminergic, glutamatergic, and GABAergic disturbances. These strategies will require, however, a greater use of neurophysiological tools to better inform clinical research. In this sense, electrophysiology and viral vector-based circuit dissection, like optogenetics, can further elucidate how exogenous cannabinoids worsen (e.g., tetrahydrocannabinol, THC) or ameliorate (e.g., cannabidiol, CBD) schizophrenia symptoms, like hallucinations, delusions, and cognitive deficits. Also, recent studies point to a complex endocannabinoid-endovanilloid interplay, including the influence of anandamide (endogenous CB₁ and TRPV₁ agonist) on cognitive variables, such as aversive memory extinction. In fact, growing interest has been devoted to TRPV₁ receptors as promising therapeutic targets. Here, these issues are reviewed with an emphasis on the neurophysiological evidence. First, we contextualize imaging and electrographic findings in humans. Then, we present a comprehensive review on rodent electrophysiology. Finally, we discuss how basic research will benefit from further combining psychopharmacological and neurophysiological tools.

Nanoparticles as potential clinical therapeutic agents in Alzheimer's disease: focus on selenium nanoparticles

INTRODUCTION

In etiology of Alzheimer's disease (AD), involvement of amyloid β (Aβ) plaque accumulation and oxidative stress in the brain have important roles. Several nanoparticles such as titanium dioxide, silica dioxide, silver and zinc oxide have been experimentally using for treatment of neurological disease. In the last decade, there has been a great interest on combination of antioxidant bioactive compounds such as selenium (Se) and flavonoids with the oxidant nanoparticles in AD. We evaluated the most current data available on the physiological effects of oxidant and antioxidant nanoparticles. Areas covered: Oxidative nanoparticles decreased the activities of reactive oxygen species (ROS) scavenging enzymes such as glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase in the brain of rats and mice. However, Se-rich nanoparticles in small size (5-15 nm) depleted Aβ formation through decreasing ROS production. Reports on low levels of Se in blood and tissue samples and the low activities of GSH-Px, catalase and SOD enzymes in AD patients and animal models support the proposed crucial role of oxidative stress in the pathogenesis of AD. Expert commentary: In conclusion, present literature suggests that Se-rich nanoparticles appeared to be a potential therapeutic compound for the treatment of AD.

Interaction of Plant Extracts with Central Nervous System Receptors

Background: Plant extracts have been used in traditional medicine for the treatment of various maladies including neurological diseases. Several central nervous system receptors have been demonstrated to interact with plant extracts and components affecting the pharmacology and thereby potentially playing a role in human disease and treatment. For instance, extracts from Hypericum perforatum (St. John’s wort) targeted several CNS receptors. Similarly, extracts from Piper nigrum, Stephania cambodica, and Styphnolobium japonicum exerted inhibition of agonist-induced activity of the human neurokinin-1 receptor. Methods: Different methods have been established for receptor binding and functional assays based on radioactive and fluorescence-labeled ligands in cell lines and primary cell cultures. Behavioral studies of the effect of plant extracts have been conducted in rodents. Plant extracts have further been subjected to mood and cognition studies in humans. Results: Mechanisms of action at molecular and cellular levels have been elucidated for medicinal plants in support of standardization of herbal products and identification of active extract compounds. In several studies, plant extracts demonstrated affinity to a number of CNS receptors in parallel indicating the complexity of this interaction. In vivo studies showed modifications of CNS receptor affinity and behavioral responses in animal models after treatment with medicinal herbs. Certain plant extracts demonstrated neuroprotection and enhanced cognitive performance, respectively, when evaluated in humans. Noteworthy, the penetration of plant extracts and their protective effect on the blood-brain-barrier are discussed. Conclusion: The affinity of plant extracts and their isolated compounds for CNS receptors indicates an important role for medicinal plants in the treatment of neurological disorders. Moreover, studies in animal and human models have confirmed a scientific basis for the application of medicinal herbs. However, additional investigations related to plant extracts and their isolated compounds, as well as their application in animal models and the conducting of clinical trials, are required.

Amitriptyline modulated Ca2+ signaling and induced Ca2+-independent cell viability in human osteosarcoma cells

Amitriptyline is a widely used tricyclic antidepressant, which acts primarily as a serotonin–norepinephrine reuptake inhibitor. This study examined the effect of amitriptyline on Ca2+ homeostasis and its related mechanism in MG63 human osteosarcoma cells. Amitriptyline evoked cytosolic-free Ca2+ concentrations ([Ca2+]i) rises concentration dependently. Amitriptyline-evoked Ca2+ entry was confirmed by Mn2+-induced quench of fura-2 fluorescence. This entry was inhibited by Ca2+ entry modulators nifedipine, econazole, SKF96365, the protein kinase C (PKC) activator phorbol 12-myristate 13 acetate but was not affected by the PKC inhibitor GF109203X. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (TG) inhibited amitriptyline-evoked [Ca2+]i rises by 95%. Conversely, treatment with amitriptyline abolished TG-evoked [Ca2+]i rises. Inhibition of phospholipase C (PLC) with U73122 inhibited amitriptyline-evoked [Ca2+]i rises by 70%. Amitriptyline killed cells at 200–500 μM in a concentration-dependent fashion. Chelating cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid/AM did not reverse amitriptyline-induced cytotoxicity. Collectively, our data suggest that in MG63 cells, amitriptyline induced [Ca2+]i rises by evoking PLC-dependent Ca2+ release from the endoplasmic reticulum and Ca2+ entry via PKC-regulated store-operated Ca2+ entry. Amitriptyline also induced Ca2+-disassociated cell death.

Agomelatine reduces brain, kidney and liver oxidative stress but increases plasma cytokine production in the rats with chronic mild stress-induced depression

Agomelatine (AGOM) as an antidepressant acts both as a melatonin-receptor agonist and a selective serotonin-receptor antagonist. As a potent melatonin derived antioxidant, AGOM might modulate depression-induced lipid peroxidation and pro-inflammatory cytokines in brain, kidney and liver. The present study explores whether AGOM protects against experimental depression-induced brain, kidney and liver oxidative stress, and plasma cytokine production in rats with chronic mild stress (CMS)-induced depression. Thirty-six rats were divided into four groups. The first group was used as an untreated control. The second group received AGOM for 4 weeks. The third group was exposed to chronic mild stress (CMS) of 4 weeks for induction depression. The fourth group received 40 mg/kg AGOM and CMS for 4 weeks. Liver and kidney lipid peroxidation levels were high in the CMS group although they were low in AGOM treatments. AGOM and AGOM + CMS treatments increased the lowered glutathione peroxidase activity and reduced glutathione levels in brain, kidney and liver of CMS group. β-carotene, vitamin A and vitamin E concentrations in the brain, kidney and liver of the four groups were not changed by CMS and AGOM treatments. However, plasma TNF-α, interleukin (IL)-1β, and IL-4 levels were high in the CMS and AGOM group and their levels were further increased by the AGOM + CMS treatment. In conclusions, AGOM induced protective effects against experimental depression-induced brain, kidney, and liver oxidative injuries through regulation of the glutathione concentrations and glutathione peroxidase activity. However, plasma cytokine productions were increased by the AGOM treatment.

Duloxetine Reduces Oxidative Stress, Apoptosis, and Ca2+ Entry Through Modulation of TRPM2 and TRPV1 Channels in the Hippocampus and Dorsal Root Ganglion of Rats

Overload of Ca²⁺ entry and excessive oxidative stress in neurons are the two main causes of depression. Activation of transient receptor potential (TRP) vanilloid type 1 (TRPV1) and TRP melastatin 2 (TRPM2) during oxidative stress has been linked to neuronal survival. Duloxetine (DULOX) in neurons reduced the effects of Ca²⁺ entry and reactive oxygen species (ROS) through glutamate receptors, and this reduction of effects may also occur through TRPM2 and TRPV1 channels. In order to better characterize the actions of DULOX in peripheral pain and hippocampal oxidative injury through modulation of TRPM2 and TRPV1, we tested the effects of DULOX on apoptosis and oxidative stress in the hippocampal and dorsal root ganglion (DRG) neurons of rats. Freshly isolated hippocampal and DRG neurons were incubated for 24 h with DULOX. In whole-cell patch-clamp and intracellular-free calcium ([Ca²⁺]) concentration (Fura-2) experiments, cumene hydroperoxide and ADP-ribose-induced TRPM2 currents in the neurons were inhibited by N-(p-amylcinnamoyl) anthranilic acid (ACA) and capsaicin-induced TRPV1 currents were inhibited by capsazepine (CPZ) incubations. TRPM2 and TRPV1 channel current densities, [Ca²⁺] concentration, apoptosis, caspase 3, caspase 9, mitochondrial depolarization, and intracellular ROS production values in the neurons were lower in the DULOX group than in controls. In addition, the above values were further decreased by DULOX + CPZ and DULOX + ACA treatments. In conclusion, TRPM2 and TRPV1 channels are involved in Ca²⁺ entry-induced neuronal death and modulation of the activity of these channels by DULOX treatment may account for their neuroprotective activity against apoptosis, excessive ROS production, and Ca²⁺ entry.

The problem of police-related cardiac arrest

The term "positional asphyxia" was originally used to describe the situation in which the upper airways becomes compromised by sharp angulation of the head or neck, or where the chest wall is splinted and the diaphragm is prevented from moving because of an unusual position of the body. The term was redefined in the early 1980s to describe sudden death during physical restraint of an individual who is in a prone position. A large percent of reported victims were overweight males. Most were in early middle age and manifesting psychotic behavior at the time of death. Most were reported to have unremarkable autopsies, save for the finding, in many cases, of cocaine or methamphetamine (more recently synthetic cannabinoids and cathinones as well). As no cause of death was apparent (other than non-specific signs such as pulmonary edema), it became common practice to attribute death to force exerted on the decedent's back. When experimental studies with human volunteers disproved this notion, the term "restraint asphyxia" was substituted for positional asphyxia, but with nearly the exact same meaning. No experimental study has ever determined the actual amount of force necessary to cause asphyxia by force applied to the back (although the range of required static force is known), nor the duration for which it must be applied. This review discusses the epidemiology and the evidence for and against the theory of "restraint/positional" asphyxia. It also considers alternative theories of causation, including the findings of studies suggesting that cardiac channelopathies/cardiomyopathies may explain many cases of ARD.