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, PKCßI, PKCßII, 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.

Evaluation of medication dosing errors in elderly patients with renal impairment
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OBJECTIVE: The administration of the usual dosage of medication in elderly patients with renal impairment can cause adverse drug reactions due to patients' decreased renal function. Using retrospective prescription analysis, in a teaching hospital, this study aimed to evaluate medication dosing errors in elderly patients with renal impairment and the risk factors for these dosing errors. MATERIALS AND METHODS: This retrospective study included elderly patients with a creatinine clearance of 59 mL/min or less who were hospitalized in a teaching hospital between July 1, 2015, and September 30, 2015. Data including the patients' age, gender, weight, serum creatinine, duration of hospital stay, and discharge prescriptions were obtained from electronic medical records. Patients with dosing errors were identified, and the risk factors for the dosing errors were statistically analyzed. RESULTS: Out of 497 patients, 164 (33%) had evidence of dosing errors. All metformin prescriptions (n = 38) were associated with dosing errors (100%), and trimetazidine was prescribed 11 times in cases where it was contraindicated (31%). The following were confirmed to be statistically significant risk factors that increased the likelihood of the dosing errors: the patient's age (odds ratio (OR): 1.050, 95% confidence interval (CI): 1.011 - 1.092), the number of drugs prescribed per patient (OR: 1.106; 95% CI: 1.012 - 1.210), and the number of drugs requiring dosing adjustments in patients with renal impairment (OR: 1.996; 95% CI: 1.614 - 2.468). CONCLUSION: There was a considerable rate of dosing errors in hospitalized elderly patients with renal impairment. It is necessary for healthcare professionals to make appropriate dosage adjustments in elderly patients with renal impairment to improve the outcomes of pharmacotherapy and patients' quality of life.
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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.

Ginsenoside Re Protects Trimethyltin-Induced Neurotoxicity via Activation of IL-6-Mediated Phosphoinositol 3-Kinase/Akt Signaling in Mice.

Ginseng (Panax ginseng), an herbal medicine, has been used to prevent neurodegenerative disorders. Ginsenosides (e.g., Re, Rb1, or Rg1) were obtained from Korean mountain cultivated ginseng. The anticonvulsant activity of ginsenoside Re (20 mg/kg/day × 3) against trimethyltin (TMT) insult was the most pronounced out of ginsenosides (e.g., Re, Rb1, and Rg1). Re itself did not significantly alter tumor necrosis factor-α (TNF-α), interferon-ϒ (IFN-ϒ), and interleukin-1ß (IL-1ß) expression, however, it significantly increases the interleukin-6 (IL-6) expression. In addition, Re attenuated the TMT-induced decreases in IL-6 protein level. Therefore, IL-6 knockout (-/-) mice were employed to investigate whether Re requires IL-6-dependent neuroprotective activity against TMT toxicity. Re significantly attenuated TMT-induced lipid peroxidation, protein peroxidation, and reactive oxygen species in the hippocampus. Re-mediated antioxidant effects were more pronounced in IL-6 (-/-) mice than in WT mice. Consistently, TMT-induced increase in c-Fos-immunoreactivity (c-Fos-IR), TUNEL-positive cells, and nuclear chromatin clumping in the dentate gyrus of the hippocampus were significantly attenuated by Re. Furthermore, Re attenuated TMT-induced proapoptotic changes. Protective potentials by Re were comparable to those by recombinant IL-6 protein (rIL-6) against TMT-insult in IL-6 (-/-) mice. Moreover, treatment with a phosphoinositol 3-kinase (PI3K) inhibitor, LY294002 (1.6 µg, i.c.v) counteracted the protective potential mediated by Re or rIL-6 against TMT insult. The results suggest that ginsenoside Re requires IL-6-dependent PI3K/Akt signaling for its protective potential against TMT-induced neurotoxicity.

Evaluation of the effects and adverse drug reactions of low-dose dexamethasone premedication with weekly docetaxel.

PURPOSE: A weekly docetaxel regimen had comparable efficacy with a tri-weekly schedule and caused significantly less severe neutropenia and febrile neutropenia. Therefore, a weekly docetaxel regimen has become increasingly common in cancer treatment. Premedication with corticosteroids can effectively prevent or reduce the severity of hypersensitivity and fluid retention. However, no recommended steroid dosage for a weekly docetaxel regimen has been established to date. The aim of this study is to compare the efficacy and complications of two different weekly docetaxel premedication protocols. METHODS: We retrospectively compared the hypersensitivity, hyperglycemia, and infection incidence associated with two weekly docetaxel premedication protocols. The control group (dexamethasone 10 mg intravenously and 4 mg orally every 12 h for four doses, starting 1 h before docetaxel administration) patients started weekly docetaxel chemotherapy between May 2012 and April 2013 at Seoul National University Hospital, and the experimental group (dexamethasone 10 mg intravenously 1 h prior to each docetaxel administration) patients started weekly docetaxel chemotherapy between May 2013 and April 2014. RESULTS: In total, 109 patients in the control group and 97 patients in the experimental group were included in this study, and there were no statistically significant differences in baseline characteristics between the two groups. The incidence of hypersensitivity and hyperglycemia were similar, but infections were observed significantly less in the experimental group (p = 0.020, OR = 0.408, 0.0190-0.0879). CONCLUSIONS: A low-dose dexamethasone premedication protocol has comparable efficacy in the prevention of docetaxel hypersensitivity with fewer infection complications. Therefore, we recommend a low-dose dexamethasone premedication protocol for weekly docetaxel regimens.

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.

Effects of vitamin D on blood pressure in patients with type 2 diabetes mellitus.

PURPOSE: Previous studies have suggested that vitamin D supplementation may decrease blood pressure in patients with type 2 diabetes, although conflicting results have been reported. The purpose of this meta-analysis was to evaluate the effects of the vitamin D supplementation on blood pressure in patients with type 2 diabetes. METHODS: A meta-analysis of published randomized controlled trials was conducted. Eligible studies were identified via a literature search of the MEDLINE (PubMed), EMBASE, and Cochrane Library databases through to May 25, 2015. The endpoint of the analysis was the change in blood pressure due to vitamin D treatment in patients with type 2 diabetes. These changes were calculated as the difference between the baseline and final measurements performed in each study. A fixed-effects model was used to calculate the combined effect estimates; in the presence of heterogeneity, a random-effects model was used. RESULTS: A total of 15 articles were included in the meta-analysis. All 15 articles, including 1,134 patients with type 2 diabetes, were analyzed for systolic blood pressure (SBP), and 13 articles, including 793 patients, were analyzed for diastolic blood pressure (DBP). The combined-effect estimate of vitamin D intervention on SBP was -0.121 mmHg (95% confidence interval (CI) -0.355 to 0.113, p = 0.311), and considerable heterogeneity was observed between studies (p < 0.001, I(2)= 74.2%). For DBP, the combined effect estimate was -0.160 mmHg (95% CI -0.298 to -0.022, p = 0.023), and no heterigenieity was observed (p = 0.673, I(2) = 0.0%). CONCLUSIONS: This study is the first meta-analysis of the effect of vitamin D supplementation on blood pressure in patients with type 2 diabetes. This meta-analysis demonstrated that vitamin D supplementation may result in a reduction in DBP in patients with type 2 diabetes. However, additional studies with large sample sizes and longer durations are needed to establish a relationship between vitamin D and blood pressure in patients with type 2 diabetes.

Awareness of the adverse effects associated with prophylactic corticosteroid use during docetaxel therapy.

PURPOSE: Weekly or tri-weekly docetaxel treatment mandates the use of dexamethasone to prevent toxicity. However, the adverse effects of prophylactic steroid use are often overlooked. We investigated the incidence of corticosteroid-associated adverse effects during docetaxel therapy, focusing on hyperglycemia and infection as well as the identification of possible risk factors. METHODS: This study was conducted through retrospective chart review of 632 patients who started docetaxel-based chemotherapy between July 2011 and June 2012 at Seoul National University Hospital. Hyperglycemia was defined as more than two random glucose levels >200 mg/dL. All documented episodes of infection that required treatment with antibiotics were regarded as infectious episodes. RESULTS: The incidences of hyperglycemia in overall patients and in patients without previous diabetes mellitus were 13.7 and 10.9%, respectively. Infectious episodes greater than grade 2 and grade 3 developed in 29.6 and 19.9% of patients, respectively. Multivariable logistic regression analysis showed that body mass index and previous diabetes mellitus were independent risk factors for hyperglycemia, whereas corticosteroid dose was not. Treatment duration and frequency of high blood glucose levels over 200 mg/dL were independent risk factors for infection. CONCLUSIONS: Due to the significant difference in patient and treatment characteristics, we could not obtain meaningful comparisons between weekly and tri-weekly docetaxel administration regimens. This study suggests that adverse effects associated with prophylactic steroid use need to be recognized and optimally managed during docetaxel therapy.

Clinical effect of a polysaccharide-rich extract of Acanthopanax senticosus on alcohol hangover.

The present study aimed to examine the effects polysaccharide-rich extract of Acanthopanax senticosus (PEA) on blood alcohol concentration (BAC) and hangover as well as blood lab parameters. A randomized, placebo-controlled, double-blind crossover trial was conducted. The PEA was orally administered before and after consuming alcohol 1.75 g/kg of pure alcohol. After alcohol consumption, BAC was measured for evaluation of alcohol pharmacokinetics. In the second day morning, subjects were asked to complete the Acute Hangover Scale (AHS) questionnarie. BAC results showed little difference between placebo and PEA groups, indicating that PEA does not have an effect on the pharmacokinetics of alcohol. However, several AHS items (i.e., tired, headache, dizziness, stomachache and nausea) and AHS total score were significantly improved by PEA. Blood lab parameters were significantly altered by alcohol in the placebo group. The alteration by alcohol of glucose and C-reactive protein (CRP) level was significantly attenuated by PEA. Therefore, PEA may have potential to reduce the severity of the alcohol hangover by inhibiting the alcohol-induced hypoglycemia and inflammatory response.

Factors affecting voriconazole plasma concentrations in patients with invasive fungal infections.

OBJECTIVE: This study retrospectively analyzed the medical records of patients with invasive fungal infections treated with voriconazole in a teaching hospital in order to identify the factors affecting plasma concentrations of voriconazole. METHODS: Patients treated with voriconazole for invasive fungal infection at the oncology department of the Samsung Medical Center, which is a tertiary teaching hospital located in Seoul, Korea, between January 2010 and May 2012 were statistically analyzed for the identification of factors affecting plasma concentrations of voriconazole. RESULTS: Of the 64 patients analyzed, 3 patients who were also treated with cytochrome P450 (CYP) 2C19 inducers showed a statistically lower plasma concentration of voriconazole compared to the other 61 patients (p = 0.034). Factors such as sex, underlying disease, age, and voriconazole dosage were not significantly associated with the median plasma concentrations of voriconazole. The different administration routes of voriconazole were also not significantly associated with the median plasma concentration, but there was a tendency for higher plasma concentrations in 28 patients receiving the drug intravenously compared to 36 patients who received it orally. CONCLUSIONS: We found that patients with invasive fungal infections receiving voriconazole and CYP2C19 inducers concomitantly had significantly lower plasma concentrations of voriconazole compared to the other patients. In addition, there was a tendency for patients to have a higher plasma concentration of voriconazole when it was administered intravenously. However, additional prospective studies are needed to confirm these results and apply them to routine clinical practice. In the future it will be important to monitor plasma concentrations of voriconazole while considering the influence of various factors that could affect the concentrations.

Risk factors for renal impairment in patients with solid tumors or multiple myeloma treated with zoledronic acid.

OBJECTIVE: Using retrospective prescription analysis, this study aimed to investigate the risk factors for renal impairment among adult solid tumor and multiple myeloma patients who have received zoledronic acid injections in a teaching hospital over the last 4 years. METHODS: We examined solid tumor and multiple myeloma patients who had received at least 1 zoledronic acid injection in a teaching hospital in Seoul with at least 2,000 beds over the 4 years between January 2008 and December 2011. The injection histories and serum creatinine levels of these patients were included in the analysis. Patients who developed renal impairment subsequent to zoledronic acid injection were identified, and the risk factors were statistically analyzed. RESULTS: In only 1 case was zoledronic acid injection reduced as directed by the creatinine clearance guidelines. Four patients whose creatinine clearance was less than 30 ml/min were injected with zoledronic acid even though its use is contraindicated in this situation. Of the 338 research subjects, 26 developed renal impairment. The following were confirmed to be statistically significant (p < 0.05) risk factors for the development of renal impairment: serum creatinine (at first injection) of greater than 1.4 mg/dl, diabetes, hypertension, thalidomide prescription, multiple myeloma, and previous pamidronate usage. CONCLUSIONS: Based on the results of this study, renal monitoring is necessary following zoledronic acid injection. In addition, for patients with renal impairment risk factors, a risk-benefit analysis must be performed before zoledronic acid is administered, and it must be administered at an appropriate dose according to the level of renal function.

Correlation of skin toxicity and hypertension with clinical benefit in advanced hepatocellular carcinoma patients treated with sorafenib.

OBJECTIVE: The purpose of this study was to identify the correlation of skin toxicity and hypertension with clinical benefit in advanced hepatocellular carcinoma (HCC) patients treated with sorafenib by analyzing medical records retrospectively. METHODS: Data from medical records was statistically analyzed to identify a correlation of skin toxicity and hypertension with treatment response and prognosis in advanced HCC patients who had received sorafenib at the Asan Medical Center from July 2010 to June 2012. This study investigated prognostic factors for overall survival and the correlation between the development of skin toxicities and hypertension. RESULTS: A total of 99 patients receiving sorafenib were included in this study. 29 patients who developed skin toxicities Grade 2 or higher showed significantly longer survival than the 70 patients who developed skin toxicities less than Grade 2 or those without skin toxicity (p = 0.024). However, development of hypertension was not related to survival (p = 0.262). In a multivariate analysis, skin toxicities were found to be good prognostic factors for overall survival (hazard ratio, 0.320; 95% CI, 0.119 - 0.861; p = 0.024) as well as low α-fetoprotein level (hazard ratio, 0.195; 95% CI, 0.076 - 0.500; p = 0.001). On the other hand, no correlation was found between the development of skin toxicities and hypertension (p = 0.109). CONCLUSIONS: Skin toxicities that are common adverse reactions in advanced HCC patients treated with sorafenib may be used as surrogate markers for clinical benefit. Therefore, early detection and proper management of these toxicities is crucial for continuing treatment with sorafenib.

Extremely low-frequency magnetic fields modulate nitric oxide signaling in rat brain.

Our previous study has shown that an extremely low-frequency magnetic field (ELF-MF) induces nitric oxide (NO) synthesis by Ca(2+) -dependent NO synthase (NOS) in rat brain. The present study was designed to confirm that ELF-MF affects neuronal NOS (nNOS) in several brain regions and to investigate the correlation between NO and nNOS activation. The exposure of rats to a 2 mT, 60 Hz ELF-MF for 5 days resulted in increases of NO levels in parallel with cGMP elevations in the cerebral cortex, striatum, and hippocampus. Cresyl violet staining and electron microscopic evaluation revealed that there were no significant differences in the morphology and number of neurons in the cerebral cortex, striatum, and hippocampus. Differently, the numbers of nNOS-immunoreactive (IR) neurons were significantly increased in those cerebral areas in ELF-MF-exposed rats. These data suggest that the increase in NO could be due to the increased expression and activation of nNOS in cells. Based on NO signaling in physiological and pathological states, ELF-MF created by electric power systems may induce various physiological changes in modern life.

An adenoviral vector encoded with the GPx-1 gene attenuates memory impairments induced by ß-amyloid (1-42) in GPx-1 KO mice via activation of M1 mAChR-mediated signalling.

In the present study, we examined whether glutathione peroxidase-1 (GPx-1), a major H2O2 scavenger in the brain, affects memory deficits induced by Aß (1-42) in mice. Treatment with 400 pmol/5 µl Aß (1-42) (i.c.v.) resulted in a reduction of GPx-1 expression in wild-type (WT) mice. An Aß (1-42)-induced reduction in acetylcholine (ACh) level was observed in the hippocampus. Treatment with Aß (1-42) consistently resulted in reduced expression and activity of choline acetyltransferase (ChAT) and in an increase in expression and activity of acetylcholinesterase (AChE). Upon examining each of the muscarinic acetylcholine receptors (mAChRs) and nicotinic AChRs, we noted that Aß (1-42) treatment selectively reduced the levels of M1 mAChR. In addition, Aß (1-42) induced a significant reduction in phospho-cAMP response element-binding protein (p-CREB) and brain-derived neurotrophic factor (BDNF) expression. The cholinergic impairments induced by Aß (1-42) were more pronounced in GPx-1 knockout mice than in WT mice. Importantly, an adenoviral vector encoded with the GPx-1 gene (Ad-GPx-1) significantly rescued Aß (1-42)-induced cholinergic impairments in GPx-1 knockout mice. In addition, M1 mAChR antagonist dicyclomine significantly counteracted Ad-GPx-1-mediated increases in p-CREB and BDNF expression, as well as memory-enhancing effects in GPx-1 knockout mice, thus indicating that M1 mAChR might be a critical mediator for the rescue effects of Ad-GPx-1. Combined, our results suggest that GPx-1 gene protected against Aß (1-42)-induced memory impairments via activation of M1 mAChR-dependent CREB/BDNF signalling.

5-HT2A receptor-mediated PKCδ phosphorylation is critical for serotonergic impairments induced by p-chloroamphetamine in mice.

p-Chloroamphetamine (PCA), an amphetamine derivative, has been shown to induce serotonergic toxicity. However, the precise mechanism of serotonergic toxicity induced by PCA remains unclear. In this study, PCA treatment (20 mg/kg, i.p.) did not significantly change 5-HT1A receptor gene expression, but significantly increased 5-HT2A receptor gene expression. Furthermore, 5-HT2A receptor antagonist MDL11939, but not 5-HT1A receptor antagonist WAY100635, significantly attenuated PCA-induced serotonergic impairments. We investigated whether PCA activated a specific isoform of protein kinase C (PKC), since previous evidence indicated the involvement of PKC in neurotoxicity induced by amphetamines. We observed that PCA treatment significantly increased the expression levels of PKCδ among all PKC isoforms. MDL11939 treatment significantly attenuated PCA-induced phosphorylation of PKCδ. However, PCA-induced increase in 5-HT2A receptor gene expression was not altered by rottlerin (a pharmacological inhibitor of PKCδ) in mice, suggesting that 5-HT2A receptor is an upstream molecule for the activation of PKCδ. Rottlerin or PKCδ knockout significantly attenuated serotonergic behaviors. However, MDL11939 did not show any additional effects against the attenuation caused by PKCδ knockout in mice, suggesting that PKCδ gene is a molecular target for 5-HT2A receptor-mediated serotonergic effects. Our results suggest that 5-HT2A receptor mediates PCA-induced serotonergic impairments via activation of PKC.δ.

Glutathione peroxidase-1 overexpressing transgenic mice are protected from cocaine-induced drug dependence.

Converging evidence has demonstrated that oxidative burdens are associated with drug dependence induced by psychostimulants. Here, we investigated whether oxidative stress directly mediates conditioned place preference and behavioral sensitization (drug dependence) induced by cocaine and whether glutathione peroxidase-1 (GPx-1), a major GPx, modulates cocaine-induced psychotoxic changes in mice. Cocaine-induced drug dependence was followed by increases in c-Fos-immunoreactivity (c-Fos-IR) in the nucleus accumbens. Simultaneously, cocaine significantly increased oxidative parameters and nuclear factor κB (NFκB) activity (i.e. nuclear translocation and DNA binding activity) in the striatum (including nucleus accumbens). Genetic depletion of GPx-1 made mice susceptible to drug dependence induced by cocaine in mice, while genetic overexpression of GPx-1 protected the mice from drug dependence. Pyrrolidine dithiocarbamate (PDTC), a NFκB inhibitor, significantly attenuated the sensitivity induced by the genetic depletion of GPx-1 in mice. However, PDTC did not exhibit any additive effects against the protection afforded by the genetic overexpression of GPx-1. Our results suggest that drug dependence induced by cocaine requires oxidative stress and NFκB activation, and that the GPx-1 gene is a potential protective factor against cocaine-induced drug dependence through positive modulation of NFκB.

P53 knockout mice are protected from cocaine-induced kindling behaviors via inhibiting mitochondrial oxidative burdens, mitochondrial dysfunction, and proapoptotic changes.

Previously we demonstrated that p53 mediates dopaminergic neurotoxicity via inducing mitochondrial burdens and proapoptotsis. However, little is known about the role of p53 in the excitotoxicity induced by psychostimulant, such as cocaine. Cocaine-induced kindling (convulsive) behaviors significantly increased p53 expression in the brain. Cocaine-induced p53 expression was more pronounced in hippocampus than in striatum or prefrontal cortex. Genetic depletion of p53 significantly attenuated cocaine-induced convulsive behaviors, followed by c-Fos immunoreactivity, and oxidative burdens in the hippocampus of mice. The antioxidant potentials mediated by genetic depletion of p53 were more pronounced in the mitochondrial-than cytosolic-fraction. Depletion of p53 significantly attenuated the changes in mitochondrial transmembrane potential, intramitochondrial Ca2+ level, and mitochondrial oxidative burdens induced by cocaine. Consistently, depletion of p53 significantly inhibited mitochondrial p53 translocation, and cleaved-PKCδ induced by cocaine. In addition, depletion of p53 protected from cytosolic cytochrome c release, and pro-apoptotic changes induced by cocaine. Importantly, the protective/anticonvulsant potentials by genetic depletion of p53 were comparable to those by pifithrin-µ (PFT), a p53 inhibitor. Our results suggest that depletion of p53 offers anticonvulsive and neuroprotective potentials mainly via attenuating mitochondrial oxidative burdens, mitochondrial dysfunction, and pro-apoptotic signalings against cocaine-induced convulsive neurotoxicity.

Blockade of platelet-activating factor receptor attenuates abnormal behaviors induced by phencyclidine in mice through down-regulation of NF-κB.

Accumulating evidence suggests that neuroinflammation is one of the important etiologic factors of abusive and neuropsychiatric disorders. Platelet-activating factor (PAF) is potent proinflammatory lipid mediat1or and plays a pivotal role in neuroinflammatory disorders through the specific PAF receptor (PAF-R). Phencyclidine (PCP) induces a psychotomimetic state that closely resembles schizophrenia. Here, we investigated the role of PAF-R in the abnormal behaviors induced by PCP in mice. Repeated treatment with PCP resulted in a significant increase in PAF-R gene expression in the prefrontal cortex (PFC) and in the hippocampus. This increase was more pronounced in the PFC than hippocampus. Treatment with PCP resulted in a significant increase in nuclear translocation of the nuclear factor kappa beta (NF-κB) p65 and DNA binding activity, indicating that the proinflammatory molecule NF-κB was increased through up-regulation of PAF-R. Consistently, NF-κB activation was significantly protected by the PAF-R antagonist, ginkgolide B (Gink B), in PAF-R knockout mice and by the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC). In addition, PCP-induced abnormal behaviors (i.e., reduced sociability, depression, cognitive impairment, and behavioral sensitization) were significantly attenuated by Gink B, in PAF-R knockout mice, and by PDTC. Importantly, PDTC did not significantly alter the attenuations observed in Gink B-treated mice or PAF-R knockout mice, indicating that NF-κB is a critical target for neuropsychotoxic modulation of PAF-R. Therefore, the results suggest that PAF-R mediates PCP-induced neuropsychotoxicity via a NF-κB-dependent mechanism, and that up-regulation of PAF-R may be associated with schizophrenia-like behavior in animal models.

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

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/µl/mouse, i.c.v.) without a significant neuronal loss, we focused on this dose for further analyses. Results showed that MCLR (4 ng/µl/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.