Tissue-specific effect of ascorbic acid supplementation on the expression of cytochrome P450 2E1 and oxidative stress in streptozotocin-induced diabetic rats

Intermittent hypoxia-hyperoxia training ameliorates cognitive impairment and neuroinflammation in a rat model of Alzheimer's disease

Alzheimer's disease (AD), characterized by severe and progressive cognitive decline, stands as one of the most prevalent and devastating forms of dementia. Based on our recent findings showing intermittent hypoxic conditioning improved neuronal function in patients with mild cognitive impairment, the present study aimed at investigating whether the neuroprotective effects of intermittent hypoxia can be replicated in a rat model of AD, which allows us to explore the underlying cellular mechanisms involving neuroinflammation, hypoxia inducible factor 1α (HIF1α), and cytochrome P450 family 2 subfamily E member 1 (CYP2E1). Forty-one adult male Wistar rats were randomly assigned to three groups: 1) Control group: received intracerebroventricular (ICV) injection of saline; 2) STZ group: received ICV injection of streptozotocin (STZ) to induce AD-like pathology; and 3) STZ + IHHT group received ICV injection of STZ as well as 15 daily sessions of intermittent hypoxia-hyperoxia training (IHHT). We observed that ICV injection of STZ inhibited spatial learning and memory in the rats assessed with Morris Water Maze test. The cognitive function declines were accompanied by increased expression of amyloid β peptide (Aβ), HIF1α, CYP2E1, and TNFα in hippocampus. Interestingly, IHHT significantly restored the STZ-induced cognitive dysfunction, while reduced expression of Aβ, CYP2E1, HIF1α and TNFα. We conclude that IHHT with mild hypoxia-hyperoxia can enhance spatial learning and memory and reduce the AD-like pathologic changes in rats. The neuroprotective outcome of IHHT may be related to anti-inflammatory effects in hippocampus.

Therapeutic treatments for diabetes mellitus-induced liver injury by regulating oxidative stress and inflammation

Diabetes mellitus (DM) is a metabolic disease that affects all systems in the body, including the liver. Numerous studies have reported that chronic DM etiology and pathogenesis complications implicate oxidative stress, generating reactive oxygen species, such as superoxide anions and free radicals. In addition, pro-inflammatory reactions are also underlying functions closely related to oxidative stress that further exacerbate pathological DM states. The liver is especially susceptible to hyperglycemia-induced oxidative stress and the related inflammation. Thus, anti-oxidation and anti-inflammation therapies are promising strategies for treating liver damage. This review summarizes therapeutic treatments attenuating the generation of oxidative stress and pro-inflammation, which also cause DM-induced liver injury. Although the treatments have several impediments to be solved, these remedies may have clinically important implications under the absence of effective drugs for the damaged liver in DM patients.

Albumin infusion ameliorates liver injury in streptozotocin-induced diabetic rats

We investigated the effect of an albumin infusion on the enzyme activity, expression level of cytochrome P450 2E1 (CYP2E1), and oxidative stress in the serum and liver of streptozotocin (STZ)-induced diabetic rats. The STZ treatment enhanced the alanine aminotransferase and aspartate aminotransferase activities in the rat serum compared with those in the untreated rats. Treatment with STZ elevated the expression and catalytic activity of CYP2E1, and the oxidative stress, and decreased the reducing potentials in the liver, suggesting the possibility of diabetes-induced liver injury. Moreover, the antioxidant activity of the serum albumin decreased in the diabetic rats. In contrast, the administration of purified albumin from the intact rats to the diabetic rats restored these deleterious liver indices in an albumin concentration-dependent manner. These results suggest that an exogenous albumin infusion alleviates liver damage induced by type 1 diabetes.

Changes of liver transcriptome profiles following oxidative stress in streptozotocin-induced diabetes in mice

Background

Oxidative-stress (OS) was causal in the development of cell dysfunction and insulin resistance. Streptozotocin (STZ) was an alkylation agent that increased reactive oxygen species (ROS) levels. Here we aimed to explore the oxidative-stress and related RNAs in the liver of STZ-induced diabetic mice.

Methods

RNA-sequencing was performed using liver tissues from STZ induced diabetic mice and controls. Pathway and Gene Ontology (GO) analyses were utilized to annotate the target genes. The differentially expressed RNAs involved in the peroxisome pathway were validated by qRT-PCR. The glucose metabolite and OS markers were measured in the normal control (NC) and STZ-induced diabetic mellitus (DM) group.

Results

The levels of serum Fasting insulin, HbA1c, Malondialdehyde (MDA) and 8-iso-prostaglandin F2α (8-iso-PGF2α) were significant higher in DM groups than NC group, while SOD activity decreased significantly in DM groups. We found 416 lncRNAs and 910 mRNAs were differentially expressed in the STZ-induced diabetic mice compared to the control group. OS associated RNAs were differentially expressed in the liver of STZ-induced diabetic mice.

Conclusion

This study confirmed that the OS was increased in the STZ-induced DM mice as evidenced by the increase of lipid peroxidation product MDA and 8-iso-PGF2α, identified aberrantly expressed lncRNAs and mRNAs in STZ-induced diabetic mice.

Susceptibility to the acute toxicity of acrylonitrile in streptozotocin-induced diabetic rats: protective effect of phenethyl isothiocyanate, a phytochemical CYP2E1 inhibitor

Diabetes mellitus is a significant global public health issue. The diabetic state not only precipitates chronic disease but also has the potential to change the toxicity of drugs and chemicals. Acrylonitrile (AN) is a potent neurotoxin widely used in industrial products. This study used a streptozotocin (STZ)-induced diabetic rat model to examine the role of cytochrome P450 2E1 (CYP2E1) in acute AN toxicity. The protective effect of phenethyl isothiocyanate (PEITC), a phytochemical inhibitor of CYP2E1, was also investigated. A higher incidence of convulsions and loss of the righting reflex, and decreased rates of survival, as well as elevated CYP2E1 activity, were observed in diabetic rats treated with AN when compared to those in non-diabetic rats, suggesting that diabetes confers susceptibility to the acute toxicity of AN. Pretreatment with PEITC (20-80 mg/kg) followed by AN injection alleviated the acute toxicity of AN in diabetic rats as evidenced by the decreased incidence of convulsions and loss of righting reflex, and increased rates of survival. PEITC pretreatment at 40 and 80 mg/kg decreased hepatic CYP2E1 activity in AN-exposed diabetic rats. PEITC pretreatment (20 mg/kg) increased the glutathione (GSH) content and glutathione S-transferase (GST) activity and further decreased ROS levels in AN-exposed diabetic rats. Collectively, STZ-induced diabetic rats were more sensitive to AN-induced acute toxicity mainly due to CYP2E1 induction, and PEITC pretreatment significantly alleviated the acute toxicity of AN in STZ-induced diabetic rats. PEITC might be considered as a potential effective chemo-preventive agent against AN-induced acute toxicity in individuals with an underlying diabetic condition.

Prophylactic role of taurine and its derivatives against diabetes mellitus and its related complications

Taurine is a conditionally essential amino acid present in the body in free form. Mammalian taurine is synthesized in the pancreas via the cysteine sulfinic acid pathway. Anti-oxidation and anti-inflammation are two main properties through which it exerts its therapeutic effects. Many studies have shown its excellent therapeutic potential against diabetes mellitus and related complications like diabetic neuropathy, retinopathy, nephropathy, hematological dysfunctions, reproductive dysfunctions, liver and pancreas related complications etc. Not only taurine, a number of its derivatives have also been reported to be important in ameliorating diabetic complications. The present review has been aimed to describe the importance of taurine and its derivatives against diabetic metabolic syndrome and related complications.

Toxicological Implications of Mitochondrial Localization of CYP2E1

Cytochrome P450 2E1 (CYP2E1) metabolizes an extensive array of pollutants, drugs, and other small molecules, often resulting in bioactivation to reactive metabolites. Therefore, it is unsurprising that it has been the subject of decades of research publications and reviews. However, while CYP2E1 has historically been studied in the endoplasmic reticulum (erCYP2E1), active CYP2E1 is also present in mitochondria (mtCYP2E1). Relatively few studies have specifically focused on mtCYP2E1, but there is growing interest in this form of the enzyme as a driver in toxicological mechanisms given its activity and location. Many previous studies have linked total CYP2E1 to conditions that involve mitochondrial dysfunction (fasting, diabetes, non-alcoholic steatohepatitis, and obesity). Furthermore, a large number of reactive metabolites that are formed by CYP2E1 through metabolism of drugs and pollutants have been demonstrated to cause mitochondrial dysfunction. Finally, there appears to be significant inter-individual variability in targeting to the mitochondria, which could constitute a source of variability in individual response to exposures. This review discusses those outcomes, the biochemical properties and toxicological consequences of mtCYP2E1, and highlights important knowledge gaps and future directions. Overall, we feel that this exciting area of research is rich with new and important questions about the relationship between mtCYP2E1, mitochondrial dysfunction, and pathology.

Antidiabetic and antioxidant effects of saponarin from Gypsophila trichotoma on streptozotocin-induced diabetic normotensive and hypertensive rats

BACKGROUND

Diabetes and hypertension are diseases that often coexist, which increases the risk of chronic organ damages and cardiovascular complications.

PURPOSE

To evaluate the effects of saponarin, isolated from Gypsophila trichotoma Wend, on blood pressure, glycemia, body weight, and liver biochemical parameters related to oxidative stress in diabetic normotensive Wistar Kyoto rats (NTR) and spontaneously hypertensive rats (SHR).

METHODS

Diabetes was induced by administration of streptozotocin (40 mg/kg, i.p.). The following biochemical parameters: reduced glutathione (GSH), malondialdehyde (MDA), total cytochrome P450, aniline hydroxylase (AH) activity, as well as the activities of antioxidant enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) were measured in the livers of euthanized rats.

RESULTS

Saponarin exerted slight antihypertensive activity in non-diabetic SHR, judged by 19% (p<0.05) decrease of the initial blood pressure. However, such effect was not observed in streptozotocin-induced diabetic SHR (SHR-D). Streptozotocin-induced diabetes was evidenced by 78% (p<0.05) and by 171% (p<0.05) increase in blood glucose level in NTR and SHR, respectively. In non-diabetic SHR the initial MDA quantity was by 36% (p<0.05) higher and the initial GSH levels were by 28% (p<0.05) lower in comparison to non-diabetic NTR. Significant decrease in the activities of GPx, GR, and GST was measured in the livers of all diabetic rats. Treatment with saponarin ameliorated the above mentioned liver parameters in both diabetic strains, however its effects were less pronounced in the diabetic SHR group.

CONCLUSION

Taken together our data indicate that diabetes and hypertension in combination are more difficult to be modulated by saponarin.

Effects of Etanercept against Transient Cerebral Ischemia in Diabetic Rats

Diabetes mellitus is known to exacerbate acute cerebral ischemic injury. Previous studies have demonstrated that infarction volumes caused by transient cerebral ischemia were greater in diabetic rats than in nondiabetic rats. Tumor necrosis factor-α (TNF-α) is a proinflammatory protein produced in the brain in response to cerebral ischemia that promotes apoptosis. Etanercept (ETN), a recombinant TNF receptor (p75)-Fc fusion protein, competitively inhibits TNF-α. Therefore, we evaluated the neuroprotective effects of chronic or acute treatment with ETN on cerebral injury caused by middle cerebral artery occlusion/reperfusion (MCAO/Re) in rats with streptozotocin-induced diabetes. Furthermore, we evaluated the effects of ETN against the apoptosis and myeloperoxidase activity. Single administration of ETN before MCAO significantly suppressed exacerbation of cerebral damage in nondiabetic rats, as assessed by infarct volume. In contrast, the diabetic state markedly aggravated MCAO/Re-induced cerebral damage despite ETN treatment within 24 h before MCAO. However, the damage was improved by repeated administration of ETN at 900 μg/kg/daily in rats in an induced diabetic state. These results suggested that repeated administration of ETN can prevent exacerbation of cerebral ischemic injury in the diabetic state and is mainly attributed to anti-inflammatory effects.

Matching Diabetes and Alcoholism: Oxidative Stress, Inflammation, and Neurogenesis Are Commonly Involved

Diabetes and alcohol misuse are two of the major challenges in health systems worldwide. These two diseases finally affect several organs and systems including the central nervous system. Hippocampus is one of the most relevant structures due to neurogenesis and memory-related processing among other functions. The present review focuses on the common profile of diabetes and ethanol exposure in terms of oxidative stress and proinflammatory and prosurvival recruiting transcription factors affecting hippocampal neurogenesis. Some aspects around antioxidant strategies are also included. As a global conclusion, the present review points out some common hits on both diseases giving support to the relations between alcohol intake and diabetes.

Aspartame Administration and Insulin Treatment Altered Brain Levels of CYP2E1 and CYP3A2 in Streptozotocin-Induced Diabetic Rats

This study demonstrates that aspartame consumption and insulin treatment in a juvenile diabetic rat model leads to increase in cytochrome P450 (CYP) 2E1 and CYP3A2 isozymes in brain. Diabetes mellitus was induced in postweaned 21-day-old Wistar male rat by streptozotocin. Animals were randomly assigned to one of the following groups: untreated control, diabetic (D), D-insulin, D-aspartame, or the D-insulin + aspartame-treated group. Brain and liver tissue samples were used to analyze the activity of CYP2E1 and CYP3A2 and protein levels. Our results indicate that combined treatment with insulin and aspartame in juvenile diabetic rats significantly induced CYP2E1 in the cerebrum and cerebellum without modifying it in the liver, while CYP3A2 protein activity increased both in the brain and in the liver. The induction of CYP2E1 in the brain could have important in situ toxicological effects, given that this CYP isoform is capable of bioactivating various toxic substances. Additionally, CYP3A2 induction in the liver and brain could be considered a decisive factor in the variation of drug response and toxicity.

Decreased level of albumin in peripheral blood mononuclear cells of streptozotocin-induced diabetic rats

We investigated the phenotypic level of albumin in peripheral blood mononuclear cells (PBMC) of streptozotocin (STZ)-induced diabetic rats. A specific reduction of albumin was identified by 2-dimensional electrophoresis and mass spectrometry. Decreased albumin content was also confirmed by immunoblotting and quantitative real-time PCR. Since albumin is a major and predominant antioxidant in plasma, the PBMC albumin may also contribute to their antioxidant activity. By measuring the amount of H₂O₂, lipid peroxidation and the redox form of glutathione, it was found that the production of the oxidative stress was elevated in STZ-diabetic rats compared to that of normal control. We suggest, therefore, that decreased albumin content may lead to the decreased antioxidant activity in the PBMC of type 1 diabetic rats.

Orally administrated ascorbic acid suppresses neuronal damage and modifies expression of SVCT2 and GLUT1 in the brain of diabetic rats with cerebral ischemia-reperfusion

Diabetes mellitus is known to exacerbate cerebral ischemic injury. In the present study, we investigated antiapoptotic and anti-inflammatory effects of oral supplementation of ascorbic acid (AA) on cerebral injury caused by middle cerebral artery occlusion and reperfusion (MCAO/Re) in rats with streptozotocin-induced diabetes. We also evaluated the effects of AA on expression of sodium-dependent vitamin C transporter 2 (SVCT2) and glucose transporter 1 (GLUT1) after MCAO/Re in the brain. The diabetic state markedly aggravated MCAO/Re-induced cerebral damage, as assessed by infarct volume and edema. Pretreatment with AA (100 mg/kg, p.o.) for two weeks significantly suppressed the exacerbation of damage in the brain of diabetic rats. AA also suppressed the production of superoxide radical, activation of caspase-3, and expression of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) in the ischemic penumbra. Immunohistochemical staining revealed that expression of SVCT2 was upregulated primarily in neurons and capillary endothelial cells after MCAO/Re in the nondiabetic cortex, accompanied by an increase in total AA (AA + dehydroascorbic acid) in the tissue, and that these responses were suppressed in the diabetic rats. AA supplementation to the diabetic rats restored these responses to the levels of the nondiabetic rats. Furthermore, AA markedly upregulated the basal expression of GLUT1 in endothelial cells of nondiabetic and diabetic cortex, which did not affect total AA levels in the cortex. These results suggest that daily intake of AA attenuates the exacerbation of cerebral ischemic injury in a diabetic state, which may be attributed to anti-apoptotic and anti-inflammatory effects via the improvement of augmented oxidative stress in the brain. AA supplementation may protect endothelial function against the exacerbated ischemic oxidative injury in the diabetic state and improve AA transport through SVCT2 in the cortex.

The role of antioxidants and other agents in alleviating hyperglycemia mediated oxidative stress and injury in liver

Several antioxidants and agents having similar antioxidant effects are known to exert beneficial effects in ameliorating the injurious effects of hyperglycemia on liver in different diabetic in vitro and in vivo models. The review deals with some of the agents which have been shown to exert protective effects on liver against hyperglycemic insult and the various mechanisms involved. The different classes of agents which protect the diabetic liver or decrease the severity of hyperglycemia mediated injury include flavonoids, catechins, and other polyphenolic compounds, curcumin and its derivatives, certain vitamins, hormones and drugs, trace elements, prototypical antioxidants and amino acids. Some of the pronounced changes mediated by the antioxidants in liver exposed to hyperglycemia include decreased oxidative stress, and alterations in carbohydrate and lipid metabolism. Other mechanisms through which the agents ameliorate hyperglycemia mediated liver injury include decrease in oxidative DNA and protein damage, restoration of mitochondrial structural and functional integrity, decrease in inflammation and improved insulin signaling. Thus, antioxidants may prove to be an important mode of defense in maintaining normal hepatic functions in diabetes.

S-allylcysteine Improves Streptozotocin-Induced Alterations of Blood Glucose, Liver Cytochrome P450 2E1, Plasma Antioxidant System, and Adipocytes Hormones in Diabetic Rats

BACKGROUND

S-allylcysteine, a garlic derivative, could have a protective effect against pathogenesis of diabetes mellitus.

OBJECTIVES

Sustained free radical generation and oxidative damage to system leads to the final conclusion phase of diabetes and also it coexists with a constant diminution in the antioxidant status.The present study aims to evaluate the therapeutic effects of S-allylcysteine (SAC) against adipocytes hormones and antioxidant defense systems of plasma and erythrocytes of treptozotocin (STZ) induced diabetes in rats.

MATERIALS AND METHODS

Diabetic rats were administered SAC (150 mg/kg b.w) orally for 45 days. At 46(th) day, the rats were anesthetized, and blood and liver sample were collected for analyzing glucose, plasma insulin, CYP2E1 activity, Thiobarbituric acid reactive substances (TBARS), hydroperoxide, enzymatic and nonenzymatic antioxidants, reduced glutathione (GSH), ceruloplasmin, plasma leptin, and adiponectin.

RESULTS

The levels of glucose, CYP2E1 activity, Thiobarbituric acid reactive substances (TBARS), hydroperoxide, and ceruloplasmin were increased significantly; whereas, the levels of plasma insulin, reduced glutathione, enzymatic and nonenzymatic antioxidants, leptin and adiponectin were decreased in experimental diabetic rats. Administration of SAC to diabetic rats led to a decrease in the levels of glucose, CYP2E1 activity, TBARS, and ceruloplasmin. In addition, the levels of plasma insulin, enzymatic and nonenzymatic antioxidants leptin and adiponectin were increased in SAC treated diabetic rats. Gliclazide, a standard drug for diabetes, was used for the comparative purpose.

CONCLUSIONS

The results of the present investigation suggest that SAC could be used as a food supplement in the treatment of diabetes characterized by provoked antioxidant status, altered blood glucose, and hormones level.

Estrogen-related receptor γ controls hepatic CB1 receptor-mediated CYP2E1 expression and oxidative liver injury by alcohol

BACKGROUND

The hepatic endocannabinoid system and cytochrome P450 2E1 (CYP2E1), a key enzyme causing alcohol-induced reactive oxygen species (ROS) generation, are major contributors to the pathogenesis of alcoholic liver disease. The nuclear hormone receptor oestrogen-related receptor γ (ERRγ) is a constitutively active transcriptional activator regulating gene expression.

OBJECTIVE

To investigate the role of ERRγ in the alcohol-mediated regulation of CYP2E1 and to examine the possibility to control alcohol-mediated oxidative stress and liver injury through an ERRγ inverse agonist.

DESIGN

For chronic alcoholic hepatosteatosis study, C57BL/6J wild-type and CB1(-/-) mice were administered alcohol for 4 weeks. GSK5182 and chlormethiazole (CMZ) were given by oral gavage for the last 2 weeks of alcohol feeding. Gene expression profiles and biochemical assays were performed using the liver or blood of mice.

RESULTS

Hepatic ERRγ gene expression induced by alcohol-mediated activation of CB1 receptor results in induction of CYP2E1, while liver-specific ablation of ERRγ gene expression blocks alcohol-induced expression of CYP2E1 in mouse liver. An ERRγ inverse agonist significantly ameliorates chronic alcohol-induced liver injury in mice through inhibition of CYP2E1-mediated generation of ROS, while inhibition of CYP2E1 by CMZ abrogates the beneficial effects of the inverse agonist. Finally, chronic alcohol-mediated ERRγ and CYP2E1 gene expression, ROS generation and liver injury in normal mice were nearly abolished in CB1(-/-) mice.

CONCLUSIONS

ERRγ, as a previously unrecognised transcriptional regulator of hepatic CB1 receptor, controls alcohol-induced oxidative stress and liver injury through CYP2E1 induction, and its inverse agonist could ameliorate oxidative liver injury due to chronic alcohol exposure.

Taurine is more effective than melatonin on cytochrome P450 2E1 and some oxidative stress markers in streptozotocin-induced diabetic rats

Melatonin and taurine have alleviative effects in streptozotocin (STZ)-induced diabetic rats. Male Wistar rats were divided into nondiabetic, diabetic, diabetic melatonin supplemented and diabetic taurine supplemented groups. At the end of the study, both blood and liver were collected for determination of some oxidative stress parameters, and hepatic cytochrome P450 2E1 (CYP2E1) enzyme activity and gene expression. An increased CYP2E1 activity and expression level with a concomitant significant change in oxidative stress parameters were found in STZ-induced diabetic rats. Taurine or melatonin supplementation to the diabetic rats alleviated these experimental parameters with a more significant effect for taurine than that of melatonin. Suppression of β-hydroxybutyrate (β-HB) production by taurine can be one of the mechanisms of a reduction in CYP2E1. Taurine was effective more than melatonin in reducing CYP2E1 activity and expression; therefore antioxidants might prove beneficial in type 1 diabetes associated with manifestations of liver injury.

Cytochrome P450 2E1 and hyperglycemia-induced liver injury

Cytochrome P450 2E1 (CYP2E1), a microsomal enzyme involved in xenobiotic metabolism and generation of oxidative stress, has been implicated in promoting liver injury. The review deals with the changes in various cellular pathways in liver linked with the changes in regulation of CYP2E1 under hyperglycemic conditions. Some of the hepatic abnormalities associated with hyperglycemia-mediated induction of CYP2E1 include increased oxidative stress, changes in mitochondrial structure and function, apoptosis, nitrosative stress, and increased ketone body accumulation. Thus, changes in regulation of CYP2E1 are associated with the injurious effects of hyperglycemia in liver.

Vitamin C, resveratrol and lipoic acid actions on isolated rat liver mitochondria: all antioxidants but different

Modulating mitochondrial antioxidant status is a nutritional issue of great interest in the treatment or prevention of several oxidative stress related diseases such as obesity. Thus, the aim of the present study was to analyze the effects of three antioxidants on hepatic mitochondrial function and antioxidant status. Isolated rat liver mitochondria were incubated with vitamin C, resveratrol and lipoic acid. The activity of antioxidant enzymes (manganese superoxide dismutase and glutathione peroxidase), ROS generation and respiratory parameters (RCR, P/O ratio and respiratory states) were measured. Vitamin C influenced mitochondrial function by decreasing of ROS generation (P < 0.0001), by stimulating the activity of manganese superoxide dismutase (197.60 ± 35.99%; P < 0.001) as well as glutathione peroxidase (15.70 ± 5.76%; P < 0.05) and by altering the activity of the electron transport chain, mainly by decreasing the P/O ratio (P < 0.05). Resveratrol induced a significant increase in manganese superoxide dismutase activity (160 ± 11.78%; P < 0.0001) and a decrease in ROS generation (P < 0.05 to P < 0.0001). By contrast, lipoic acid inhibited glutathione peroxidase activity (16.48 ± 3.27%; P < 0.05) and induced the uncoupling of the electron transport chain (P < 0.01). Moreover, this antioxidant induced a strong decrease in the P/O ratio (P < 0.05 to P < 0.0001). In conclusion, our results suggest that the three tested antioxidants produced direct effects on mitochondrial function, although the magnitude and intensity of these actions were significantly different, which may have implications when administrated as antioxidants.

Constitutive expression of drug metabolizing enzymes and related transcription factors in cattle testis and their modulation by illicit steroids

In veterinary species, little information about extrahepatic drug metabolism is actually available. Therefore, the presence of foremost drug metabolizing enzymes (DMEs) and related transcription factors mRNAs was initially investigated in cattle testis; then, their possible modulation following the in vivo exposure to illicit growth promoters (GPs), which represent a major issue in cattle farming, was explored. All target genes were expressed in cattle testis, albeit to a lower extent compared to liver ones; furthermore, illicit protocols containing dexamethasone and 17β-oestradiol significantly up-regulated cytochrome P450 1A1, 2E1, oestrogen receptor-α and peroxisome proliferator-activated receptor-α mRNA levels. Overall, the constitutive expression of foremost DMEs and related transcription factors was demonstrated for the first time in cattle testis and illicit GPs were shown to affect pre-transcriptionally some of them, with possible consequences upon testicular xenobiotic drug metabolism.

Altered retinoic acid metabolism in diabetic mouse kidney identified by O isotopic labeling and 2D mass spectrometry

BACKGROUND

Numerous metabolic pathways have been implicated in diabetes-induced renal injury, yet few studies have utilized unbiased systems biology approaches for mapping the interconnectivity of diabetes-dysregulated proteins that are involved. We utilized a global, quantitative, differential proteomic approach to identify a novel retinoic acid hub in renal cortical protein networks dysregulated by type 2 diabetes.

METHODOLOGY/PRINCIPAL FINDINGS

Total proteins were extracted from renal cortex of control and db/db mice at 20 weeks of age (after 12 weeks of hyperglycemia in the diabetic mice). Following trypsinization, (18)O- and (16)O-labeled control and diabetic peptides, respectively, were pooled and separated by two dimensional liquid chromatography (strong cation exchange creating 60 fractions further separated by nano-HPLC), followed by peptide identification and quantification using mass spectrometry. Proteomic analysis identified 53 proteins with fold change >or=1.5 and p<or=0.05 after Benjamini-Hochberg adjustment (out of 1,806 proteins identified), including alcohol dehydrogenase (ADH) and retinaldehyde dehydrogenase (RALDH1/ALDH1A1). Ingenuity Pathway Analysis identified altered retinoic acid as a key signaling hub that was altered in the diabetic renal cortical proteome. Western blotting and real-time PCR confirmed diabetes-induced upregulation of RALDH1, which was localized by immunofluorescence predominantly to the proximal tubule in the diabetic renal cortex, while PCR confirmed the downregulation of ADH identified with mass spectrometry. Despite increased renal cortical tissue levels of retinol and RALDH1 in db/db versus control mice, all-trans-retinoic acid was significantly decreased in association with a significant decrease in PPARbeta/delta mRNA.

CONCLUSIONS/SIGNIFICANCE

Our results indicate that retinoic acid metabolism is significantly dysregulated in diabetic kidneys, and suggest that a shift in all-trans-retinoic acid metabolism is a novel feature in type 2 diabetic renal disease. Our observations provide novel insights into potential links between altered lipid metabolism and other gene networks controlled by retinoic acid in the diabetic kidney, and demonstrate the utility of using systems biology to gain new insights into diabetic nephropathy.

Hypoglycemic activity of Buchholzia coriacea (Capparaceae) seeds in streptozotocin-induced diabetic rats and mice

The present study evaluates the possible hypoglycemic activity and ameliorative effects of oral administration of ethanol extracts (EEBC) and butanol fraction (BFBC) of Buchholzia coriacea seeds, a plant in use traditionally for treating diabetes, hypertension, rheumatism, cold, cough and catarrh, in streptozotocin (STZ)-induced diabetic mice and rats. Fasting blood glucose (FBG) levels were evaluated before and after extracts administration. EEBC and BFBC significantly decreased (P<0.05) FBG in hyperglycemic mice and normoglycemic rats within 4 and 12 h, respectively after extract administration. The administration of EEBC, BFBC and glibenclamide (a standard antidiabetic drug) for 10 days significantly lowered (P<0.05) FBG level in STZ-induced diabetic rats by 55%, 64% and 56%, respectively. EEBC and BFBC significantly (P<0.05) decreased hepatic injury induced by STZ as evident in the decreased activity of serum alanine amino transferase and aspartate amino transferase compared to in the STZ-only treated group. Similarly, both extracts significantly decreased (P<0.05) the elevated levels of serum creatinine, urea, total cholesterol, triglyceride and thiobarbituric acid reactive species (TBARS) products in diabetic rats. Serum superoxide dismutase activity was significantly enhanced (P<0.05) by treatments with EEBC, BFBC and glibenclamide. Overall, the results suggest that B. coriacea seeds contain a potent hypoglycemic and antioxidant agent suggested to be a flavone glycoside concentrated in BFBC which may find clinical application in amelioration of diabetes-induced secondary complications.

Bax inhibitor 1 regulates ER-stress-induced ROS accumulation through the regulation of cytochrome P450 2E1

This study investigated the molecular mechanism by which Bax inhibitor 1 (BI1) abrogates the accumulation of reactive oxygen species (ROS) in the endoplasmic reticulum (ER). Electron uncoupling between NADPH-dependent cytochrome P450 reductase (NPR) and cytochrome P450 2E1 (P450 2E1) is a major source of ROS on the ER membrane. ER stress produced ROS accumulation and lipid peroxidation of the ER membrane, but BI1 reduced this accumulation. Under ER stress, expression of P450 2E1 in control cells was upregulated more than in BI1-overexpressing cells. In control cells, inhibiting P450 2E1 through chemical or siRNA approaches suppressed ROS accumulation, ER membrane lipid peroxidation and the resultant cell death after ER stress. However, it had little effect in BI1-overexpressing cells. In addition, BI1 knock down also increased ROS accumulation and expression of P450 2E1. In a reconstituted phospholipid membrane containing purified BI1, NPR and P450 2E1, BI1 dose-dependently decreased the production of ROS. BI1 bound to NPR with higher affinity than P450 2E1. Furthermore, BI1 overexpression reduced the interaction of NPR and P450 2E1, and decreased the catalytic activity of P450 2E1, suggesting that the flow of electrons from NPR to P450 2E1 can be modulated by BI1. In summary, BI1 reduces the accumulation of ROS and the resultant cell death through regulating P450 2E1.

Hepatic changes in adenine nucleotide levels and adenosine 3'-monophosphate forming enzyme in streptozotocin-induced diabetic mice

To elucidate the pathophysiological significance of adenosine 3'-monophosphate (3'-AMP) forming enzyme in mice, the effect of streptozotocin (STZ) on the enzyme activities and adenine nucleotide levels in the ICR mice (4-week-old) liver was examined. After 2 weeks, treatment with a single dosage of STZ (100, 150 or 200 mg/kg i.p.) induced a dose-dependent hyperglycemia and hypoinsulinemia but had no effect on serum alanine aminotransferase activity, indicating that STZ generated type 1 diabetes without hepatitis. In the diabetic liver, the activities of superoxide dismutase (SOD), catalase and ATP levels decreased, and the microsomal CYP2E1 activity increased. Changes of these biological activities might disrupt the cellular homeostatic balance of reactive oxygen species (ROS) production. The activities of 3'-AMP forming enzyme, one of the ribonucleases, in hepatic homogenates were not altered. However, in the STZ 200 mg/kg group, the cytosolic forming enzyme activities were enhanced, and inversely, the mitochondrial activity was reduced significantly, indicating that the decrease in the mitochondrial activity may be accelerated by development of diabetes due to the decrease in the antioxidant defense system and/or increase in ROS production. With the decrease in the 3'-AMP forming enzyme activity, the levels of 3'-AMP, a P-site inhibitor of adenylate cyclase, in mitochondrial were significantly reduced. These results obtained suggested that change in the mitochondrial 3'-AMP forming enzyme activity might reflect the pathophysiological change of mitochondrial function with the development of diabetes. Our results also suggested that change in cytosolic enzyme activity might serve as a new biomarker of oxidative stress because significant negative correlation between the activities of cytosolic 3'-AMP forming enzyme and SOD was found in the early stage of diabetes.

Attenuation of Biochemical Parameters in Streptozotocin-induced Diabetic Rats by Oral Administration of Extracts and Fractions of Cephalotaxus sinensis

Cephalotaxus sinensis (C. sinensis) large size, evergreen tree common in China and utilized for numerous effective pharmacological applications in Chinese traditional medicine. The hepato-renal effects of C. sinensis were evaluated in vivo using Streptozotocin (STZ)-induced diabetic rats as an tentative model. Animals were orally treated with 80% EtOH extract (aq.EE), H(2)O extract (WtE) and ethylacetate (EaF)/butanol fractions (BtF) of C. sinensis (200 mg/kg, b.w.) for 28 days whereas control received vehicle merely. The degree of fortification was measured by using biochemical parameters like serum transaminases (ALT and AST), alkaline phosphatase (ALP), creatinine, urea and urine sugar. Meanwhile, the histopathological studies were conducted out to support the above parameters. Administration of C. sinensis aq.EE/BtF (p<0.05) and EaF (p<0.01) patently prevented STZ-induced elevation levels of serum ALT, AST, ALP, creatinine, urea, urine sugar and increase body weight respectively, which were comparable with the standard drug tolbutamide, while WtE did not show any significant effect (p>0.05). Phytochemical studies revealed the presence of saponins, terpenes, sterols and flavonoids in C. sinensis which could be responsible for the possible hepato-renal protective action. The results sustain the fact that the extract/fractions of C. sinensis have an immense potential to be developed further into a phytomedicine.