Yu Jeung Lee

Repeated exposure to far infrared ray attenuates acute restraint stress in mice via inhibition of JAK2/STAT3 signaling pathway by induction of glutathione peroxidase-1

Exposure to far-infrared ray (FIR) has been shown to exert beneficial effects on cardiovascular and emotional disorders. However, the precise underlying mechanism mediated by FIR remains undetermined. Since restraint stress induces cardiovascular and emotional disorders, the present study investigated whether exposure to FIR affects acute restraint stress (ARS) in mice. c-Fos-immunoreactivity (IR) was significantly increased in the paraventricular hypothalamic nucleus (PVN) and dorsomedial hypothalamic nucleus (DMH) in response to ARS. The increase in c-Fos-IR parallels that in oxidative burdens in the hypothalamus against ARS. Exposure to FIR significantly attenuated increases in the c-Fos-IR, oxidative burdens and corticosterone level. ARS elicited decreases in GSH/GSSG ratio, cytosolic Cu/Zn-superoxide dismutase (SOD-1), glutathione peroxidase (GPx), and glutathione reductase (GR) activities. FIR-mediated attenuation was particularly observed in ARS-induced decrease in GPx, but not in SOD-1 or GR activity. Consistently, ARS-induced decreases in GPx-1-immunoreactivity in PVN and DMH, and decreases in GPx-1 expression in the hypothalamus were significantly attenuated by FIR. ARS-induced significant increases in phosphorylation of JAK2/STAT3, and nuclear translocation and DNA-binding activity of NFκB were observed in the hypothalamus. Exposure to FIR selectively attenuated phosphorylation of JAK2/STAT3, but did not diminish nuclear translocation and DNA-binding activity of NFκB, suggesting that JAK2/STAT3 constitutes a critical target for FIR-mediated pharmacological potential. ARS-induced increase in c-Fos-IR in the PVN and DMH of non-transgenic mice was significantly attenuated by FIR exposure or JAK2/STAT3 inhibitor AG490. GPx-1 overexpressing transgenic mice significantly protected increases in the c-Fos-IR and corticosterone level induced by ARS. However, neither FIR exposure nor AG490 significantly affected attenuations by genetic overexpression of GPx-1. Moreover, AG490 did not exhibit any additional positive effects against the attenuation by genetic overexpression of GPx-1 or FIR exposure. Our results indicate that exposure to FIR significantly protects ARS-induced increases in c-Fos-IR and oxidative burdens via inhibition of JAK2/STAT3 signaling by induction of GPx-1.

Beneficial Effects of Red Yeast Rice on High-Fat Diet-Induced Obesity, Hyperlipidemia, and Fatty Liver in Mice.

Obesity is a common cause of hyperlipidemia, which is a major coronary risk factor. Previous studies have shown red yeast rice (RYR) effectiveness in lowering low-density lipoprotein cholesterol. The aim of this study was to investigate the effects of RYR on obesity and hyperlipidemia. Mice were randomly separated into five groups: the control group with a normal diet, the high-fat diet (HFD) group fed a HFD without any treatment, and HFD-fed groups supplemented with RYR (1 g/kg/day for 8 weeks, 1 g/kg/day for 12 weeks, and 2.5 g/kg/day for 8 weeks). Body weight was recorded twice and food intake thrice weekly. Liver and fat pads were surgically removed and weighed. The levels of lipid parameters, liver enzymes, and leptin levels were measured. The HFD feeding resulted in obesity, which was associated with increases in body weight, liver weight, fat pad weight, liver enzymes, and plasma leptin levels with the development of hyperlipidemia. RYR prevented weight gain and fat pad weight in mice fed a HFD. RYR alleviated blood lipid parameters, liver enzymes, and leptin levels, and improved atherogenic index. These findings suggest that RYR has therapeutic potential in treating obesity and hyperlipidemia.

Treatment with Mountain-Cultivated Ginseng Alleviates Trimethyltin-Induced Cognitive Impairments in Mice via IL-6-Dependent JAK2/STAT3/ERK Signaling

Panax ginseng is the most widely used herbal medicine for improving cognitive functions. The pharmacological activity and underlying mechanisms of mountain-cultivated ginseng, however, have yet to be clearly elucidated, in particular, against trimethyltin-induced cognitive dysfunction. We previously reported that interleukin-6 plays a protective role against trimethyltin-induced cognitive dysfunction. Because of this, we have implemented a study system that uses interleukin-6 null (-/-) and wild-type mice. Interestingly, mountain-cultivated ginseng significantly upregulated interleukin-6 expression. With this study, we sought to determine whether the interleukin-6-dependent modulation of the Janus kinase 2/signal transducer activator of transcription 3 and extracellular signal-regulated kinase signaling network is also associated with the pharmacological activity of mountain-cultivated ginseng against trimethyltin-induced cognitive dysfunction. Trimethyltin treatment (2.4 mg/kg, intraperitoneal) causes the downregulation of Janus kinase 2/signal transducer activator of transcription 3, extracellular signal-regulated kinase signaling, and impairment of the cholinergic system. We found that mountain-cultivated ginseng treatment (50 mg/kg, intraperitoneal) significantly attenuated cognitive impairment normally induced by trimethyltin by upregulating p-Janus kinase 2/signal transducer activator of transcription 3, p-extracellular signal-regulated kinase signaling, and the cholinergic system. Trimethyltin-induced cognitive impairments were more pronounced in interleukin-6 (-/-) mice than wild-type mice, and they were markedly reduced by treatment with either mountain-cultivated ginseng or recombinant interleukin-6 protein (6 ng, intracerebroventricular). Additionally, treatment with either AG490 (20 mg/kg, intraperitoneal), a Janus kinase 2/signal transducer activator of transcription 3 inhibitor, or U0126 (2 µg/head, intracerebroventricular), an extracellular signal-regulated kinase inhibitor, reversed the effects of mountain-cultivated ginseng treatment. The effects of mountain-cultivated ginseng treatment were comparable to those of recombinant interleukin-6 protein in interleukin-6 (-/-) mice. Our results, therefore, suggest that mountain-cultivated ginseng acts through interleukin-6-dependent activation of Janus kinase 2/signal transducer activator of transcription 3/extracellular signal-regulated kinase signaling in order to reverse cognitive impairment caused by trimethyltin treatment.

Genetic overexpressing of GPx‐1 attenuates cocaine‐induced renal toxicity via induction of anti‐apoptotic factors

The present study investigates the role of the glutathione peroxidase (GPx)‐1 gene in cocaine‐induced renal damage in mice. Multiple doses of cocaine increased lipid peroxidation, protein oxidation, and glutathione oxidation in the kidney of the non‐transgenic mice (non‐TG mice). The enzymatic activities of GPx and glutathione reductase were significantly decreased in non‐TG mice, whereas superoxide dismutase was increased in the early phase of cocaine exposure. Treatment with cocaine resulted in significant decreases in expression of Bcl‐2 and Bcl‐xl in the kidney of non‐TG mice, which resulted in significant increases in Bax and cleaved‐caspase 3. Consistently, cocaine‐induced tubular epithelial vacuolization and focal tubular necrosis were mainly observed in the proximal tubules in the kidneys of non‐TG mice. These renal pathologic changes were much less pronounced in GPx‐1 TG than in non‐TG mice. These results suggest that the GPx‐1 gene is a protective factor against nephrotoxicity induced by cocaine via interactive modulations between antioxidant and cell survival signaling processes.

Genetic depletion of glutathione peroxidase-1 potentiates nephrotoxicity induced by multiple doses of cocaine via activation of angiotensin II AT1 receptor.

ABSTRACT We investigated the possible roles of angiotensin II type 1 receptor (AT1R) and oxidative stress responsive nuclear factor κB (NFκB) in renal damage caused by multiple doses of cocaine in glutathione peroxidase (GPx)-1 gene-depleted mice. Treatment with cocaine resulted in significant increases in malondialdehyde, protein carbonyl, and pro-apoptotic Bax expression and decreases in the ratio of glutathione (GSH) and its oxidized form (GSSG), GSH-dependent enzymes, and anti-apoptotic factors in the kidney. These alterations were more pronounced in GPx-1 knockout (−/−) mice than in wild type (WT) mice. Notably, the AT1R antagonist losartan protected against the renal toxicity induced by cocaine, whereas the NFκB inhibitor pyrrolidine dithiocarbamate was not protective. The toxicity was more pronounced in GPx-1 (−/−) mice than in WT mice. The protective effect afforded by losartan against cocaine toxicity appeared to be more sensitive in GPx-1 (−/−) mice than that in WT mice. These losartan-mediated protective effects were inhibited by the phosphatidyl-inositol-3-kinase (PI3K) inhibitor LY294002, indicating that losartan provides significant protection from cocaine-induced renal toxicity through PI3K/Akt signaling. Our results suggest that genetic inhibition of GPx-1 potentiates cocaine-induced renal damage via activation of AT1R by inhibition of PI3K-Akt signaling, and that AT1R can be a therapeutic target against renal toxicity induced by cocaine.

Exposure to far-infrared ray attenuates methamphetamine-induced impairment in recognition memory through inhibition of protein kinase C δ in male mice: Comparison with the antipsychotic clozapine

We have previously demonstrated that repeated treatment with methamphetamine (MA) results in a recognition memory impairment via upregulation of protein kinase C (PKC) δ and downregulation of the glutathione peroxidase‐1 (GPx‐1)‐dependent antioxidant system. We also demonstrated that far‐infrared ray (FIR) attenuates acute restraint stress via induction of the GPx‐1 gene. Herein, we investigated whether exposure to FIR modulates MA‐induced recognition memory impairment in male mice, and whether cognitive potentials mediated by FIR require modulation of the PKCδ gene, extracellular signal‐regulated kinase (ERK) 1/2, and glutathione‐dependent system. Repeated treatment with MA significantly increased PKCδ expression and its phosphorylation out of PKC isoenzymes (i.e., PKCα, PKCβI, PKCβII, PKCζ, and PKCδ expression) in the prefrontal cortex of mice. Exposure to FIR significantly attenuated MA‐induced increase in phospho‐PKCδ and decrease in phospho‐ERK 1/2. In addition, FIR further facilitated the nuclear factor E2‐related factor 2 (Nrf2)‐dependent glutathione synthetic system. Moreover, L‐buthionine‐(S, R)‐sulfoximine, an inhibitor of glutathione synthesis, counteracted the FIR‐mediated phospho‐ERK 1/2 induction and memory‐enhancing activity against MA insult. More important, positive effects of FIR are comparable to those of genetic depletion of PKCδ or the antipsychotic clozapine. Our results indicate that FIR protects against MA‐induced memory impairment via activations of the Nrf2‐dependent glutathione synthetic system, and ERK 1/2 signaling by inhibition of the PKCδ gene.

Role of dopamine D1 receptor in 3-fluoromethamphetamine-induced neurotoxicity in mice

&NA; 3‐Fluoromethamphetamine (3‐FMA) is an illegal designer drug of methamphetamine (MA) derivative. Up to date, little is known about the neurotoxic potential of 3‐FMA. In the present study, we investigated the role of dopamine receptors in neurotoxicity induced by 3‐FMA in comparison with MA (35 mg/kg, i.p.) as a control drug. Here we found that 3‐FMA (40, 60 or 80 mg/kg, i.p.) produced mortality in a dose‐dependent manner in mice. Treatment with 3‐FMA (40 mg/kg, i.p.) resulted in significant hyperthermia, oxidative stress and microgliosis (microglial differentiation into M1 phenotype) followed by pro‐apoptotic changes and the induction of terminal deoxynucleotidyl transferase dUDP nick end labeling (TUNEL)‐positive cells. Moreover, 3‐FMA significantly produced dopaminergic impairments [i.e., increase in dopamine (DA) turnover rate and decreases in DA level, and in the expression of tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT‐2)] with behavioral impairments. These dopaminergic neurotoxic effects of 3‐FMA were comparable to those of MA. SCH23390, a dopamine D1 receptor antagonist, but not sulpiride, a dopamine D2 receptor antagonist significantly attenuated 3‐FMA‐induced neurotoxicity. Although both SCH23390 and sulpiride attenuated MA‐induced dopaminergic neurotoxicity, sulpiride is more effective than SCH23390 on the dopaminergic neurotoxicity. Interestingly, SCH23390 treatment positively modulated 3‐FMA‐induced microglial activation (i.e., SCH23390 inhibited M1 phenotype from 3‐FMA insult, but activated M2 phenotype). Therefore, our results suggest that the activation of dopamine D1 receptor is critical to 3‐FMA‐induced neurotoxicity, while both dopamine D1 and D2 receptors (dopamine D2 receptor > dopamine D1 receptor) mediate MA‐induced dopaminergic neurotoxicity.

Ginsenoside Re protects against phencyclidine-induced behavioral changes and mitochondrial dysfunction via interactive modulation of glutathione peroxidase-1 and NADPH oxidase in the dorsolateral cortex of mice

We investigated whether ginsenoside Re (Re) modulates phencyclidine (PCP)-induced sociability deficits and recognition memory impairments to extend our recent finding. We examined the role of GPx-1 gene in the pharmacological activity of Re against mitochondrial dysfunction induced by PCP in the dorsolateral cortex of mice. Since mitochondrial oxidative stress activates NADPH oxidase (PHOX), we applied PHOX inhibitor apocynin for evaluating interactive modulation between GPx-1 and PHOX against PCP neurotoxicity. Sociability deficits and recognition memory impairments induced by PCP were more pronounced in GPx-1 knockout (KO) than in wild type (WT) mice. PCP-induced mitochondrial oxidative stress, mitochondrial dysfunction, and membrane translocation of p47phox were more evident in GPx-1 KO than in WT. Re treatment significantly attenuated PCP-induced neurotoxic changes. Re also significantly attenuated PCP-induced sociability deficits and recognition memory impairments. The attenuation by Re was comparable to that by apocynin. The attenuation was more obvious in GPx-1 KO than in WT. Importantly, apocynin did not show any additional positive effects on the neuroprotective activity of Re, indicating that PHOX is a molecular target for therapeutic activity of Re. Our results suggest that Re requires interactive modulation between GPx activity and PHOX (p47phox) to exhibit neuroprotective potentials against PCP insult.

Genetic overexpression of glutathione peroxidase-1 attenuates microcystin-leucine-arginine-induced memory impairment in mice

ABSTRACT Microcystin‐leucine‐arginine (MCLR) is the most common form of microcystins, which are environmental toxins produced by cyanobacteria, and its hepatotoxicity has been well‐documented. However, the neurotoxic potential of MCLR remains to be further elucidated. In the present study, we investigated whether intracerebroventricular (i.c.v.) infusion of MCLR induces mortality and neuronal loss in the hippocampus of mice. Because we found that MCLR impairs memory function in the hippocampus at a low dose (4 ng/&mgr;l/mouse, i.c.v.) without a significant neuronal loss, we focused on this dose for further analyses. Results showed that MCLR (4 ng/&mgr;l/mouse, i.c.v.) significantly increased oxidative stress (i.e., malondialdehyde, protein carbonyl, and synaptosomal ROS) in the hippocampus. In addition, MCLR significantly increased superoxide dismutase (SOD) activity without corresponding induction of glutathione peroxidase (GPx) activity, and thus led to significant decrease in the ratio of GPx/SODs activity. The GSH/GSSG ratio was also significantly reduced after MCLR treatment. GPx‐1 overexpressing transgenic mice (GPx‐1 Tg) were significantly protected from MCLR‐induced memory impairment and oxidative stress. The DNA binding activity of nuclear factor erythroid‐derived 2‐related factor 2 (Nrf2) in these mice was significantly enhanced, and the ratios of GPx/SODs activity and GSH/GSSG returned to near control levels in the hippocampus. Importantly, memory function exhibited a significant positive correlation with the ratios of GPx/SODs activity and GSH/GSSG in the hippocampus of MCLR‐treated non‐transgenic (non‐Tg)‐ and GPx‐1 Tg‐mice. Combined, our results suggest that MCLR induces oxidative stress and memory impairment without significant neuronal loss, and that GPx‐1 gene constitutes an important protectant against MCLR‐induced memory impairment and oxidative stress via maintaining antioxidant defense system homeostasis, possibly through the induction of Nrf2 transcription factor. Graphical abstract Figure. No caption available. HighlightsA low dose of MCLR induces memory losses without significant neuronal degeneration.MCLR‐induced memory loss is possibly via reductions in GPx/SODs and GSH/GSSG.GPx‐1 overexpression inhibits MCLR‐induced memory loss via up‐regulation of Nrf2.

Glutathione peroxidase-1 overexpressing transgenic mice are protected from neurotoxicity induced by microcystin-leucine-arginine

Although it has been well‐recognized that microcystin‐leucine‐arginine (MCLR), the most common form of microcystins, induces neurotoxicity, little is currently known about the underlying mechanism for this neurotoxicity. Here, we found that MCLR (10 ng/μL/mouse, i.c.v.) induces significant neuronal loss in the hippocampus of mice. MCLR‐induced neurotoxicity was accompanied by oxidative stress, as shown by a significant increase in the level of 4‐hydroxynonenal, protein carbonyl, and reactive oxygen species (ROS). Superoxide dismutase‐1 (SOD‐1) activity was significantly increased, but glutathione peroxidase (GPx) level was significantly decreased following MCLR insult. In addition, MCLR significantly inhibited GSH/GSSG ratio, and significantly induced NFκB DNA binding activity. Because reduced activity of GPx appeared to be critical for the imbalance between activities of SODs and GPx, we utilized GPx‐1 overexpressing transgenic mice to ascertain the role of GPx‐1 in this neurotoxicity. Genetic overexpression of GPx‐1 or NFκB inhibitor pyrrolidine dithiocarbamate (PDTC) significantly attenuated MCLR‐induced hippocampal neuronal loss in mice. However, PDTC did not exert any additive effect on neuroprotection mediated by GPx‐1 overexpression, indicating that NFκB is a neurotoxic target of MCLR. Combined, these results suggest that MCLR‐induced neurotoxicity requires oxidative stress associated with failure in compensatory induction of GPx, possibly through activation of the transcription factor NFκB.