TRP Channels in Oxidative Stress Signalling.

It is well established that the accumulation of high levels of reactive oxygen species (ROS), due to excessive generation of ROS and/or impaired antioxidant capacity of cells, can result in oxidative stress and cause oxidative damage to cells and their functions [...].

Noopept Attenuates Diabetes-Mediated Neuropathic Pain and Oxidative Hippocampal Neurotoxicity via Inhibition of TRPV1 Channel in Rats.

Neuropathic pain and oxidative neurotoxicity are two adverse main actions of diabetes mellitus (DM). The expression levels of calcium ion (Ca2+) permeable TRPV1 channels are high in the dorsal root ganglion (DRGs) and hippocampus (HIPPO). TRPV1 is activated by capsaicin and reactive free oxygen radicals (fROS) to mediate peripheral neuropathy and neurotoxicity. Noopept (NP) acted several protective antioxidant actions against oxidative neurotoxicity. As DM is known to increase the levels of fROS, the protective roles of antioxidant NP were evaluated on the DM-mediated neurotoxicity and neuropathic pain via the modulation of TRPV1 in rats. Thirty-six rats were equally divided into control, NP, DM (streptozotocin, STZ), and STZ + NP groups. A decrease on the STZ-mediated increase of neuropathic pain (via the analyses of Von Frey and hot plate) and blood glucose level was observed by the treatment of NP. A protective role of NP via downregulation of TRPV1 activity on the STZ-induced increase of apoptosis, mitochondrial fROS, lipid peroxidation, caspase -3 (CASP-3), caspase -9 (CASP-9), TRPV1 current density, glutathione (GSH), cytosolic free Zn2+, and Ca2+ concentrations in the DRGs and HIPPO was also observed. The STZ-mediated decrease of glutathione peroxidase, GSH, vitamin E, and ß-carotene concentrations in the brain cortex, erythrocyte, liver, kidney, and plasma was also attenuated by the treatment of NP. The STZ-mediated increase of TRPV1, CASP-3, and CASP-9 expressions was decreased in the DRGs and HIPPO by the treatment of NP. In conclusion, the treatment of NP induced protective effects against STZ-induced adverse peripheral pain and HIPPO oxidative neurotoxicity. These effects might attribute to the potent antioxidant property of NP.

The protective role of selenium against dental amalgam-induced intracellular oxidative toxicity through the TRPV1 channel in DBTRG glioblastoma cells.

OBJECTIVE: The exposure to mercury (Hg) from dental amalgams is a suspected causative factor in neurological diseases. This study investigated the toxic effects of two different amalgam compositions related to Hg and the protective effects of selenium against the toxic effects of Hg through the TRPV1 channel in the human DBTRG glioblastoma cell line. METHODOLOGY: Six groups of the cells were organized. Analyses of cell viability, apoptosis, caspase 3 and caspase 9 activities, mitochondrial membrane depolarization, reactive oxygen species (ROS) production, and Western Blotting for protein expression levels were performed. RESULTS: Cell viability values were lower in amalgam with high copper (HCu) and low copper (LCu) groups independently of time but were increased by selenium and capsazepine (p<0.001 and p<0.05). Conversely, apoptosis rates, caspase 3 and caspase 9 expression, ROS formation, mitochondrial membrane depolarization, and protein expression levels were higher in the HCu and LCu groups but were decreased by selenium (p<0.001 and p<0.05). CONCLUSIONS: Selenium combined with an amalgam of either HCu or LCu decreases the toxic effects created by Hg in human DBTRG glioblastoma cells.

The protective role of selenium against dental amalgam-induced intracellular oxidative toxicity through the TRPV1 channel in DBTRG glioblastoma cells

Abstract Objective The exposure to mercury (Hg) from dental amalgams is a suspected causative factor in neurological diseases. This study investigated the toxic effects of two different amalgam compositions related to Hg and the protective effects of selenium against the toxic effects of Hg through the TRPV1 channel in the human DBTRG glioblastoma cell line. Methodology Six groups of the cells were organized. Analyses of cell viability, apoptosis, caspase 3 and caspase 9 activities, mitochondrial membrane depolarization, reactive oxygen species (ROS) production, and Western Blotting for protein expression levels were performed. Results Cell viability values were lower in amalgam with high copper (HCu) and low copper (LCu) groups independently of time but were increased by selenium and capsazepine (p<0.001 and p<0.05). Conversely, apoptosis rates, caspase 3 and caspase 9 expression, ROS formation, mitochondrial membrane depolarization, and protein expression levels were higher in the HCu and LCu groups but were decreased by selenium (p<0.001 and p<0.05). Conclusions Selenium combined with an amalgam of either HCu or LCu decreases the toxic effects created by Hg in human DBTRG glioblastoma cells.

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 (mpkCCDcl4). 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.

Modulator role of infliximab and methotrexate through the transient receptor potential melastatin 2 (TRPM2) channel in neutrophils of patients with rheumatoid arthritis: a pilot study.

INTRODUCTION: Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disease causing symmetric polyarthritis. In this study, we aimed to investigate the effects of infliximab (INF) and methotrexate (MTX) on apoptosis, oxidative stress, and calcium signaling in the neutrophils of RA patients. MATERIAL AND METHODS: Neutrophils were isolated from 10 patients with newly diagnosed RA and 10 healthy controls. They were divided into four groups (control, RA, RA + MTX, RA + INF) and incubated with MTX and INF. In the cell viability (MTT) test, the ideal non-toxic dose and incubation time of MTX were found to be 0.1 mM and 1 h, respectively. The neutrophils were also incubated with the TRPM2 channel blocker N-(p-amylcinnamoyl) anthranilic acid (ACA). RESULTS: Intracellular free Ca2+ concentration, intracellular reactive oxygen species (ROS) production, mitochondrial depolarization, lipid peroxidation, apoptosis, and caspase 3 and caspase 9 activities were found to be significantly higher in the neutrophils of RA patients compared to controls. MTT, reduced glutathione (GSH) level, and glutathione peroxidase (GSHPx) activity were significantly lower in the neutrophils of RA patients. However, MTT, GSH and GSHPx values were detected to be significantly increased with INF and MTX therapies. The Ca2+ concentrations were further decreased by the ACA therapy. CONCLUSIONS: Our results suggest that INF and MTX are useful antagonists in apoptosis and mitochondrial oxidative stress in the neutrophils of RA patients. INF and MTX decreased the Ca2+ concentration through inhibition of the TRPM2 channel in the neutrophils of RA patients. It may be a new pathway in the mechanisms of anti-rheumatic drugs.

Albumin evokes Ca2+-induced cell oxidative stress and apoptosis through TRPM2 channel in renal collecting duct cells reduced by curcumin.

In proteinuric nephropathies of chronic kidney disease, the epithelial cells of the nephron including the collecting duct are exposed to high concentrations of luminal albumin. Albumin is taken up from collecting duct cells by endocytosis causing excessive reactive oxygen species (ROS) production and a proinflammatory response. Curcumin used in the traditional medicine possesses anti-inflammatory and antioxidant effects. ROS and ADP-ribose (ADPR) activate the cation channel TRPM2. We hypothesize, that albumin-induced cell stress and proinflammatory response are mediated by Ca2+ and can be reduced by curcumin. The cortical collecting duct (CCD) cells mpkCCDc14 exhibit spontaneous and inducible Ca2+ oscillations, which can be blocked by pre-treatment with curcumin. Curcumin accumulates in plasma membrane and intracellular vesicles, where it interferes with TRPM2 and decreases the influx of Ca2+. Albumin reduces cell viability and increases apoptosis, NF-κB activation, and mitochondrial membrane depolarization via Ca2+-dependent signaling, which results in increased ROS production. Albumin-induced cell stress is diminished by the inhibition of TRPM2 after administration of curcumin and ADPR (PARP1) inhibitors. Curcumin did not reduce the Ca2+ elevation induced by thapsigargin in Ca2+-free medium, but it reduced the function of store-operated Ca2+ channels and ATP-evoked Ca2+ response. In conclusion, albumin-induced oxidative stress is mediated by Ca2+-dependent signaling via TRPM2 and leads to cell damage and a proinflammatory response, strengthening the role of CCD cells in the progression of chronic kidney disease.

Inhibitions of anandamide transport and FAAH synthesis decrease apoptosis and oxidative stress through inhibition of TRPV1 channel in an in vitro seizure model.

The expression level of TRPV1 is high in hippocampus which is a main epileptic area in the brain. In addition to the actions of capsaicin (CAP) and reactive oxygen species (ROS), the TRPV1 channel is activated in neurons by endogenous cannabinoid, anandamide (AEA). In the current study, we investigated the role of inhibitors of TRPV1 (capsazepine, CPZ), AEA transport (AM404), and FAAH (URB597) on the modulation of Ca2+ entry, apoptosis, and oxidative stress in in vitro seizure-induced rat hippocampus and human glioblastoma (DBTRG) cell line. The seizure was induced in the hippocampal and DBTRG neurons using in vitro 4-aminopyridine (4-AP) to trigger a seizure-like activity model. CPZ and AM404 were fully effective in reversing 4-AP-induced intracellular free Ca2+ concentration of the hippocampus and TRPV1 current density of DBTRG. However, AEA and CAP did not activate TRPV1 in the URB597-treated neurons. Hence, we observed TRPV1 blocker effects of URB597 in the DBTRG neurons. In addition, the AM404 and CPZ treatments decreased intracellular ROS production, mitochondrial membrane depolarization, apoptosis, caspases 3 and 9 values in the hippocampus. In conclusion, the results indicate that inhibition of AEA transport, FAAH synthesis, and TRPV1 activity can result in remarkable neuroprotective effects in the epileptic neurons. Possible molecular pathways of involvement of capsazepine (CPZ) and AM4040 in anandamide and capsaicin (CAP)-induced apoptosis, oxidative stress, and Ca2+ accumulation through TRPV1 channel in the seizure-induced rat hippocampus and human glioblastoma neurons. The TRPV1 channel is activated by different stimuli including reactive oxygen species (ROS), anandamide (AEA), and CAP and it is blocked by capsazepine (CPZ). Cannabinoid receptor type 1 (CB1) is also activated by AEA. The AEA levels in cytosol are decreased by fatty acid amide hydrolase (FAAH) enzyme. Inhibition of FAAH through URB597 induces stimulation of CB1 receptor through accumulation AEA. URB597 acts antiepileptic effects through inhibition of TRPV1. Overloaded Ca2+ concentration of mitochondria can induce an apoptotic program by stimulating the release of apoptosis-promoting factors such as caspases 3 and caspase 9 by generating ROS due to respiratory chain damage. AM404 and CPZ reduce TRPV1 channel activation and Ca2+ entry in the in vitro 4-AP seizure model-induced hippocampal and glioblastoma neurons.

Calorie restriction protects against apoptosis, mitochondrial oxidative stress and increased calcium signaling through inhibition of TRPV1 channel in the hippocampus and dorsal root ganglion of rats.

The TRPV1 channel is activated in neurons by capsaicin, oxidative stress, acidic pH and heat factors, and these factors are attenuated by the antioxidant role of calorie restriction (CR). Hence, we investigated the hypothesis that the antioxidant roles of CR and food frequency (FF) may modulate TRPV1 activity and apoptosis through inhibition of mitochondrial oxidative stress in hippocampal (HIPPON) and dorsal root ganglion neurons (DRGN). We investigated the contribution of FF and CR to neuronal injury and apoptosis through inhibition of TRPV1 in rats. We assigned rats to control, FF and FF + CR groups. A fixed amount of food ad libitum was supplemented to the control and FF groups for 20 weeks, respectively. FF + CR group were fed the same amount of food as the control group but with 20% less calories during the same period. In major results, TRPV1 currents, intracellular Ca2+ levels, apoptosis, reactive oxygen species, mitochondrial depolarization, PARP-1 expression, caspase 3 and 9 activity and expression values were found to be increased in the HIPPON and DRGN following FF treatment, and these effects were decreased following FF + CR treatment. The FF-induced decrease in cell viability of HIPPO and DRGN, and vitamin E concentration of brain, glutathione peroxidase, vitamin A, and ß-carotene values of the HIPPO, DRGN, plasma, liver and kidney were increased by FF + DR treatment, although lipid peroxidation levels in the same samples were decreased. In conclusion, CR reduces FF-induced increase of oxidative stress, apoptosis and Ca2+ entry through TRPV1 in the HIPPON and DRGN. Our findings may be relevant to the etiology and treatment of obesity following CR treatment.

Corrigendum: The neuroprotective action of dexmedetomidine on apoptosis, calcium entry and oxidative stress in cerebral ischemia-induced rats: Contribution of TRPM2 and TRPV1 channels.

This corrects the article DOI: 10.1038/srep37196.

Menthol evokes Ca2+ signals and induces oxidative stress independently of the presence of TRPM8 (menthol) receptor in cancer cells.

Menthol is a naturally occurring monoterpene alcohol possessing remarkable biological properties including antipruritic, analgesic, antiseptic, anti-inflammatory and cooling effects. Here, we examined the menthol-evoked Ca2+ signals in breast and prostate cancer cell lines. The effect of menthol (50-500µM) was predicted to be mediated by the transient receptor potential ion channel melastatin subtype 8 (TRPM8). However, the intensity of menthol-evoked Ca2+ signals did not correlate with the expression levels of TRPM8 in breast and prostate cancer cells indicating a TRPM8-independent signaling pathway. Menthol-evoked Ca2+ signals were analyzed in detail in Du 145 prostate cancer cells, as well as in CRISPR/Cas9 TRPM8-knockout Du 145 cells. Menthol (500µM) induced Ca2+ oscillations in both cell lines, thus independent of TRPM8, which were however dependent on the production of inositol trisphosphate. Results based on pharmacological tools point to an involvement of the purinergic pathway in menthol-evoked Ca2+ responses. Finally, menthol (50-500µM) decreased cell viability and induced oxidative stress independently of the presence of TRPM8 channels, despite that temperature-evoked TRPM8-mediated inward currents were significantly decreased in TRPM8-knockout Du 145 cells compared to wild type Du 145 cells.

Involvement of TRPM2 and TRPV1 channels on hyperalgesia, apoptosis and oxidative stress in rat fibromyalgia model: Protective role of selenium.

Fibromyalgia (FM) results in pain characterized by low selenium (Se) levels, excessive Ca2+ influx, reactive oxygen species (ROS) production, and acidic pH. TRPM2 and TRPV1 are activated by ROS and acid; nevertheless, their roles have not been elucidated in FM. Therefore, we investigated the contribution of TRPM2 and TRPV1 to pain, oxidative stress, and apoptosis in a rat model of FM and the therapeutic potential of Se. Thirty-six rats were divided into four groups: control, Se, FM, and FM + Se. The Se treatment reduced the FM-induced increase in TRPM2 and TRPV1 currents, pain intensity, intracellular free Ca2+, ROS, and mitochondrial membrane depolarization in the sciatic (SciN) and dorsal root ganglion (DRGN) neurons. Furthermore, Se treatment attenuated the FM-induced decrease in cell viability in the DRGN and SciN, glutathione peroxidase, and reduced glutathione and α-tocopherol values in the DRGN, SciN, brain, muscle, and plasma; however, lipid peroxidation levels were decreased. Se also attenuated PARP1, caspase 3, and 9 expressions in the SciN, DRGN, and muscle. In conclusion, Se treatment decreased the FM-induced increase in hyperalgesia, ROS, apoptosis, and Ca2+ entry through TRPM2 and TRPV1 in the SciN and DRGN. Our findings may be relevant to the elucidation and treatment of FM.

Inhibition of the TRPM2 and TRPV1 Channels through Hypericum perforatum in Sciatic Nerve Injury-induced Rats Demonstrates their Key Role in Apoptosis and Mitochondrial Oxidative Stress of Sciatic Nerve and Dorsal Root Ganglion.

Sciatic nerve injury (SNI) results in neuropathic pain, which is characterized by the excessive Ca2+ entry, reactive oxygen species (ROS) and apoptosis processes although involvement of antioxidant Hypericum perforatum (HP) through TRPM2 and TRPV1 activation has not been clarified on the processes in SNI-induced rat, yet. We investigated the protective property of HP on the processes in the sciatic nerve and dorsal root ganglion neuron (DRGN) of SNI-induced rats. The rats were divided into five groups as control, sham, sham+HP, SNI, and SNI+HP. The HP groups received 30 mg/kg HP for 4 weeks after SNI induction. TRPM2 and TRPV1 channels were activated in the neurons by ADP-ribose or cumene peroxide and capsaicin, respectively. The SNI-induced TRPM2 and TRPV1 currents and intracellular free Ca2+ and ROS concentrations were reduced by HP, N-(p-amylcinnamoyl) anthranilic acid (ACA), and capsazepine (CapZ). SNI-induced increase in apoptosis and mitochondrial depolarization in sciatic nerve and DRGN of SNI group were decreased by HP, ACA, and CapZ treatments. PARP-1, caspase 3 and 9 expressions in the sciatic nerve, DRGN, skin, and musculus piriformis of SNI group were also attenuated by HP treatment. In conclusion, increase of mitochondrial ROS, apoptosis, and Ca2+ entry through inhibition of TRPM2 and TRPV1 in the sciatic nerve and DRGN neurons were decreased by HP treatment. The results may be relevant to the etiology and treatment of SNI by HP.

Targeting breast cancer cells by MRS1477, a positive allosteric modulator of TRPV1 channels.

There is convincing epidemiological and experimental evidence that capsaicin, a potent natural transient receptor potential cation channel vanilloid member 1 (TRPV1) agonist, has anticancer activity. However, capsaicin cannot be given systemically in large doses, because of its induction of acute pain and neurological inflammation. MRS1477, a dihydropyridine derivative acts as a positive allosteric modulator of TRPV1, if added together with capsaicin, but is ineffective, if given alone. Addition of MRS1477 evoked Ca2+ signals in MCF7 breast cancer cells, but not in primary breast epithelial cells. This indicates that MCF7 cells not only express functional TRPV1 channels, but also produce endogenous TRPV1 agonists. We investigated the effects of MRS1477 and capsaicin on cell viability, caspase-3 and -9 activities and reactive oxygen species production in MCF7 cells. The fraction of apoptotic cells was increased after 3 days incubation with capsaicin (10 µM) paralleled by increased reactive oxygen species production and caspase activity. These effects were even more pronounced, when cells were incubated with MRS1477 (2 µM) either alone or together with CAPS (10 µM). Capsazepine, a TRPV1 blocker, inhibited both the effect of capsaicin and MRS1477. Whole-cell patch clamp recordings revealed that capsaicin-evoked TRPV1-mediated current density levels were increased after 3 days incubation with MRS1477 (2 µM). However, the tumor growth in MCF7 tumor-bearing immunodeficient mice was not significantly decreased after treatment with MRS1477 (10 mg/ kg body weight, i.p., injection twice a week). In conclusion, in view of a putative in vivo treatment with MRS1477 or similar compounds further optimization is required.

Selenium potentiates the anticancer effect of cisplatin against oxidative stress and calcium ion signaling-induced intracellular toxicity in MCF-7 breast cancer cells: involvement of the TRPV1 channel.

BACKGROUND: In breast cancers, calcium signaling is a main cause of proliferation and apoptosis of breast cancer cells. Although previous studies have implicated the transient receptor potential vanilloid 1 (TRPV1) cation channel, the synergistic inhibition effects of selenium (Se) and cisplatin in cancer and the suppression of ongoing apoptosis have not yet been investigated in MCF-7 breast cancer cells. This study investigates the anticancer properties of Se through TRPV1 channel activity in MCF-7 breast cancer cell line cultures when given alone or in combination with cisplatin. MATERIALS: The MCF-7 cells were divided into four groups: the control group, the Se-treated group (200 nM), the cisplatin-treated group (40 µM) and the Se + cisplatin-treated group. RESULTS: The intracellular free calcium ion concentration and current densities increased with TRPV1 channel activator capsaicin (0.01 mM), but they decreased with the TRPV1 blocker capsazepine (0.1 mM), Se, cisplatin, and Se + cisplatin incubations. However, mitochondrial membrane depolarization, apoptosis, and the caspase 3, and caspase 9 values increased in the Se-treated group and the cisplatin-treated group, although Western blot (procaspase 3 and 9) results and the cell viability levels decreased with the Se and Se + cisplatin treatments. Apoptosis and caspase-3 were further increased with the Se + cisplatin treatment. Intracellular reactive oxygen species production increased with the cisplatin treatment, but not with the Se treatment. CONCLUSION: This study's results report, for the first time, that at a cellular level, Se and cisplatin interact on the same intracellular toxic cascade, and the combination of these two drugs can result in a remarkable anticancer effect through modulation of the TRPV1.

The neuroprotective action of dexmedetomidine on apoptosis, calcium entry and oxidative stress in cerebral ischemia-induced rats: Contribution of TRPM2 and TRPV1 channels.

Dexmedetomidine (DEX) may act as an antioxidant through regulation of TRPM2 and TRPV1 channel activations in the neurons by reducing cerebral ischemia-induced oxidative stress and apoptosis. The neuroprotective roles of DEX were tested on cerebral ischemia (ISC) in the cultures of rat primary hippocampal and DRG neurons. Fifty-six rats were divided into five groups. A placebo was given to control, sham control, and ISC groups, respectively. In the third group, ISC was induced. The DEX and ISC+DEX groups received intraperitoneal DEX (40 µg/kg) 3, 24, and 48 hours after ISC induction. DEX effectively reversed capsaicin and cumene hydroperoxide/ADP-ribose-induced TRPV1 and TRPM2 densities and cytosolic calcium ion accumulation in the neurons, respectively. In addition, DEX completely reduced ISC-induced oxidative toxicity and apoptosis through intracellular reactive oxygen species production and depolarization of mitochondrial membrane. The DEX and ISC+DEX treatments also decreased the expression levels of caspase 3, caspase 9, and poly (ADP-ribose) polymerase in the hippocampus and DRG. In conclusion, the current results are the first to demonstrate the molecular level effects of DEX on TRPM2 and TRPV1 activation. Therefore, DEX can have remarkable neuroprotective impairment effects in the hippocampus and DRG of ISC-induced rats.

Synergic Effects of Doxorubicin and Melatonin on Apoptosis and Mitochondrial Oxidative Stress in MCF-7 Breast Cancer Cells: Involvement of TRPV1 Channels.

Transient receptor transient receptor potential vanilloid 1 (TRPV1) is a Ca(2+)-permeable channel gated by oxidative stress and capsaicin (CAP) and modulated by melatonin (MEL) and capsazepine (CPZ). A combination of doxorubicin (DOX) and MEL may offer a potential therapy for breast cancer by exerting antitumor and anti-apoptotic effects and modulating Ca(2+) influx and TRPV1 activity. We aimed to investigate the effects of MEL and DOX on the oxidative toxicity of MCF-7 human breast cancer cells, in addition to the activity of the TRPV1 channel and apoptosis. The MCF-7 cells were divided into the following six treatment groups: control, incubated with MEL (0.3 mM), incubated with 0.5 µM DOX, incubated with 1 µM DOX, incubated with MEL + 0.5 µM DOX, or incubated with MEL + 1 µM DOX. The intracellular free Ca(2+) concentration was higher in the DOX groups than in the control, and the concentration was decreased by MEL. The intracellular free Ca(2+) concentration was further increased by treatment with the TRPV1 channel activator CAP (0.01 mM), and it was decreased by the CPZ (0.1 mM). The intracellular production of reactive oxygen species, mitochondrial membrane depolarization, apoptosis level, procaspase 9 and PARP activities, and caspase 3 and caspase 9 activities were higher in the DOX and MEL groups than in the control. Apoptosis and the activity of caspase 9 were further increased in the DOX plus MEL groups. Taken together, the findings indicate that MEL supported the effects of DOX by activation of TRPV1 and apoptosis, as well as by inducing MCF-7 cell death. As the apoptosis and caspase activity of cancer cells increase because of their elevated metabolism, MEL may be useful in supporting their apoptotic capacity.

Melatonin and selenium reduce plasma cytokine and brain oxidative stress levels in diabetic rats.

BACKGROUND: Hyperglycaemia-induced progression of brain and erythrocyte oxidative injuries might be modulated by melatonin and selenium as potent antioxidants. The present study was conducted to explore whether melatonin and selenium protect against diabetic brain and erythrocyte oxidative stress levels in streptozotocin (STZ)-induced diabetic rats. MATERIALS AND METHODS: Seventy rats were equally divided into seven groups. The first and second groups were used as untreated and placebo treated controls. The third group was treated with STZ to induce diabetes. The fourth and sixth groups received 10 mg kg(-1) melatonin. The fifth and seventh groups were treated with 1.5 mg kg(-1) selenium (sodium selenite). The sixth and seventh groups were treated with STZ administered with melatonin and selenium as described for the fourth and fifth groups. RESULTS: Brain and erythrocyte lipid peroxidation levels and plasma IL-1ß and IL-4 levels were high in the STZ group, although they were low in melatonin and selenium treatments. Decreased glutathione peroxidase, reduced glutathione, total antioxidant status, vitamins A and vitamin E values in brain and erythrocyte of STZ group were increased by melatonin and selenium treatments. DISCUSSION: Melatonin and selenium induced protective effects against diabetes-induced brain and erythrocyte oxidative injuries through regulation of the antioxidant level and cytokine production.