Dose-dependent Manner In Liver Research Articles

Synergistic hepatoprotective effects of ω-3 and ω-6 fatty acids from Indian flax and sesame seed oils against CCl4-induced oxidative stress-mediated liver damage in rats

Flaxseed (FS) and sesame seed (SS) are traditional and functional foods in traditional Indian medicine for treating various disorders. The present study investigated the hepatoprotective effects of bioactive-fatty acids (FAs) from FS and SS against carbon tetrachloride (CCl4)-induced hepatic damage in rats. Pre and post-treatments for 28 consecutive days significantly increased the activities of in vivo antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POX), whereas, lipid peroxidation (LPO) activity was markedly decreased in a dose-dependent manner in liver and kidneys. A significant reduction was observed in the hematological parameters like aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin in the serum of post-treated animals compared to the negative control. The results were confirmed histopathologically. The results suggested that the ω-3 and ω-6 FAs from flaxseed oil (FSO) and sesame seed oil (SSO), respectively, showed potential synergistic hepatoprotective and antioxidant effects that were mediated mainly by ω-3 and ω-6 FAs present in the respective seed oils.

Protective effect of caffeic acid phenethyl ester against imidacloprid-induced hepatotoxicity by attenuating oxidative stress, endoplasmic reticulum stress, inflammation and apoptosis

Imidacloprid (IMI) is a widely used neonicotinoid pesticide in the world, its environmental and human health risk has particularly attracted the attention of researchers. Caffeic acid phenethyl ester (CAPE), an active polyphenol of propolis, has many pharmacological activities including free radical scavenger, anti-inflammatory, and anti-oxidant. In this study, protective effect of CAPE against IMI induced liver injury in mice was performed. Administration of 1 and 2.5 mg/kg CAPE markedly prevented serum AST and ALT increase in 5 mg/kg IMI-induced mice. CAPE significantly downregulated liver NO generation and lipid peroxidation, and upregulated glutathione, catalase, superoxide dismutase and glutathione peroxidase in a dose-dependent manner in liver of IMI-induced mice. Endoplasmic reticulum stress represented by the swelling of endoplasmic reticulum was observed by transmission electron microscope in IMI group. Pretreatment of 2.5 mg/kg CAPE significantly attenuated the endoplasmic reticulum stress induced by IMI in liver. Western blot analysis illustrated that pretreatment of CAPE downregulated the upregulation of TNF-α and IFN-γ induced by IMI in liver of mice. Moreover, the increase of positive apoptotic hepatocytes further suggested apoptosis might be involved in IMI-induced hepatotoxicity. Pretreatment of 1 and 2.5 mg/kg CAPE significantly decreased positive apoptotic hepatocytes, suggested that CAPE prevented apoptosis in liver of IMI-induced mice. In conclusion, CAPE prevented liver injury in IMI-induced mice via attenuation of oxidative stress, endoplasmic reticulum stress, inflammation and apoptosis. Our findings may have broad biological and environmental implications for future research on the therapeutic strategy to prevent liver injury induced by pesticides.

Eugenia caryophyllus Extract Exerts Hypocholesterolemic and Antioxidant Effects in High-Cholesterol-Fed Rats

Background: Eugenia caryophyllus (clove) is an important aromatic household spice. The plant is believed to possess medicinal properties and is commonly used in herbal preparations by traditional healers in the treatment of different ailments and diseases. Objectives: We investigated the lipid-lowering and antioxidant effects of aqueous extract of Eugenia caryophyllus on high-cholesterol-fed rats. Materials and Methods: Cholesterol (40 mg/0.3 mL) was administered to induce hypercholesterolemia in rats by oral gavage, and Eugenia caryophyllus (100 or 200 mg/kg) and Questran (0.26 g/kg) were administered five times a week for eight consecutive weeks. Serum lipid-profiles, lipid peroxidation (LPO), and antioxidant parameters were examined in liver and heart post mitochondrial fraction (PMF). Aspartate and alanine aminotransferase (ALT and AST) activities and liver tissue histology were used to evaluate tissue toxicity. Results: Hypercholesterolemia produced a noticeable decrease in serum HDL-c, whereas a concurrent elevation in serum LDL-c, total cholesterol, and triglycerides as well as serum ALT and AST was observed. Furthermore, hypercholesterolemia remarkably decreased antioxidant status, but LPO content was increased. These indices were significantly attenuated in hypercholesterolemic rats treated with E. caryophyllus extract (100 or 200 mg/kg of body weight). Specifically, reduced glutathione (GSH) concentration was increased in a dose dependent manner in liver and heart PMF. Conclusions: These results demonstrate that the hypolipidemic and antioxidative effects of aqueous extract of E. caryophyllus might be due to its ability to ameliorate lipid profiles, enhance antioxidant activities, and delay the lipid peroxidation process. This confirms the previously identified protective roles of E. caryophyllus in human health.

Investigation of in vitro and in vivo antioxidant potential of secoisolariciresinol diglucoside

The present study was designed to evaluate the in vitro and in vivo ameliorative antioxidant potential of secoisolariciresinol diglucoside (SDG). In vitro antioxidant activity of synthetic SDG was carried out using DPPH, reducing power potency, and DNA protection assays. Wistar albino rats weighing 180-220 g were used for in vivo studies and liver damage was induced in the experimental animals by a single intraperitoneal (I.P.) injection of CCl(4) (2 g/kg b.w.). Intoxicated animals were treated orally with synthetic SDG at (12.5 and 25 mg/kg b.w.) and Silymarin (25 mg/kg) for 14 consecutive days. The levels of catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), and lipid peroxidase (LPO) were measured in liver and kidney homogenates. The synthetic SDG exerts high in vitro antioxidant potency as it could scavenge DPPH at a IC(50) value of 78.9 μg/ml and has dose-dependent reducing power potency and protected DNA at 0.5 mg/ml concentration. Oral administration of synthetic SDG at 12.5 and 25 mg/kg b.w. showed significant protection compared to Silymarin (25 mg/kg) and the activities of CAT, SOD, and POX were markedly increased (P < 0.05), whereas LPO significantly decreased (P < 0.001) in a dose-dependent manner in liver and kidney in both pre- and post-treatment groups when compared to toxin-treated group. The results of in vitro and in vivo investigations revealed that synthetic SDG at 25 mg/kg b.w. is associated with beneficial changes in hepatic enzyme activities and thereby plays a key role in the prevention of oxidative damage in immunologic system.

Oxidative stress and gene expression in diverse tissues of Oryzias javanicus exposed to 17β-estradiol

Transcriptional changes in the expression of stress-related genes (catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, metallothionein, and ubiquitin) in intestinal, liver and muscle tissues of Javanese medaka (Oryzias javanicus) exposed to 17-estradiol (E2) were investigated using real-time quantitative PCR. The lipid peroxidation levels and superoxide dismutase activity in liver tissues was also examined at various exposure concentrations. In fish exposed to 10, 100 and 1000 g/L E2 the level of catalase mRNA increased significantly in intestinal and muscle tissues, while expression of the glutathione peroxidase gene showed the opposite trend in liver and muscle tissues. Expression of the glutathione S-transferase gene increased in a dose-dependent manner in liver and muscle tissues of fish exposed to E2, relative to the non-exposed control group. The level of glutathione reductase mRNA increased markedly in the liver tissues of all fish exposed to 100 and 1000 g/L E2, but decreased in intestinal tissues. The metallothionein gene was strongly downregulated in intestinal and liver tissues of fish exposed to E2, but slightly upregulated in muscle tissues. In all fish exposed to 100 and 1000 g/L E2 expression of the ubiquitin gene increased markedly in liver and muscle tissue, but not in intestinal tissues. Lipid peroxidation and superoxide dismutase activities increased significantly in all 17-estradiol treatment groups, and were correlated to the exposure concentration. Thus, E2 exposure differentially affected the transcription of a range of stress-related genes in various tissues of Javanese medaka, suggesting that analysis of transcriptional changes in these genes could be used as a rapid assay of the effects of E2 exposure.

Cholesterol metabolite, 5-cholesten-3β-25-diol-3-sulfate, promotes hepatic proliferation in mice

Oxysterols are well known as physiological ligands of liver X receptors (LXRs). Oxysterols, 25-hydroxycholesterol (25HC) and 27-hydroxycholesterol as endogenous ligands of LXRs, suppress cell proliferation via LXRs signaling pathway. Recent reports have shown that sulfated oxysterol, 5-cholesten-3β-25-diol-3-sulfate (25HC3S) as LXRs antagonist, plays an opposite direction to oxysterols in lipid biosynthesis. The present report was to explore the effect and mechanism of 25HC3S on hepatic proliferation in vivo. Following administration, 25HC3S had a 48h half life in the circulation and widely distributed in mouse tissues. Profiler™ PCR array and RTqPCR analysis showed that either exogenous or endogenous 25HC3S generated by overexpression of oxysterol sulfotransferase (SULT2B1b) plus administration of 25HC significantly up-regulated the proliferation gene expression of Wt1, Pcna, cMyc, cyclin A, FoxM1b, and CDC25b in a dose-dependent manner in liver while substantially down-regulating the expression of cell cycle arrest gene Chek2 and apoptotic gene Apaf1. Either exogenous or endogenous administration of 25HC3S significantly induced hepatic DNA replication as measured by immunostaining of the PCNA labeling index and was associated with reduction in expression of LXR response genes, such as ABCA1 and SREBP-1c. Synthetic LXR agonist T0901317 effectively blocked 25HC3S-induced hepatic proliferation. Conclusions: 25HC3S may be a potent regulator of hepatocyte proliferation and oxysterol sulfation may represent a novel regulatory pathway in liver proliferation via inactivating LXR signaling.

Metabolites and JAK/STAT pathway were involved in the liver and spleen damage in male Wistar rats fed with mequindox

Mequindox (MEQ) is a novel synthetic quinoxaline 1,4-dioxides antibacterial agent and growth promoter in animal husbandry. This study was to investigate whether reactive oxygen species (ROS), the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway, suppressors of cytokine signaling (SOCS) and inflammatory cytokines were involved in toxicities of MEQ. Our data demonstrated that high dose of MEQ (275 mg/kg) apparently led to tissue impairment combined with imbalance of redox in liver. In liver and spleen samples, hydroxylation metabolites and desoxymequindox were detected, directly confirming the potential link of N → O group reduction metabolism with its organ toxicity. Moreover, up-regulation of JAK/STAT, SOCS family, tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) were also observed in the high-dose group. Meanwhile, significant changes of oxidative stress indices in liver were observed in the high-dose group. As for NADPH subunit, the mRNA levels of many subunits were significantly up-regulated at low doses but down-regulated in a dose-dependent manner in liver and spleen, suggesting an involvement of NADPH in MEQ metabolism and ROS generation. In conclusion, we reported the dose-dependent long-term toxicity as well as the discussion of the potential mechanism and pathways of MEQ, which raised further awareness of its toxicity following with the dose change.

Dose-dependent binding of trichloroethylene to hepatic DNA and protein at low doses in mice

Trichloroethylene (TCE) is a widely used industrial chemical and a low level contaminant of surface and ground water in industrialized areas. It is weakly mutagenic in several test systems and carcinogenic in rodents. However, the mechanism for its carcinogenicity is not known. We investigated the binding of [1,2- 14C]TCE ([ 14C]TCE) to liver DNA and proteins in male B6C3F1 mice at doses more relevant to humans than used previously. The time course for the binding was studied in animals dosed with 4.1 μg [ 14C]TCE/kg body weight (b.w.) and sacrificed between 0.5 and 120 h after i.p. injection. A dose response study was carried out in mice given [ 14C]TCE at doses between 2 μg/kg and 200 mg/kg b.w. and sacrificed 2 h post-treatment. [ 14C]TCE associated with the DNA and protein extracts was measured using accelerator mass spectrometry. The highest level of protein binding (2.4 ng/g protein) was observed 1 h after the treatment followed by a rapid decline, indicating pronounced instability of the adducts and/or rapid turnover of liver proteins. DNA binding was biphasic with the first peak (75 pg/g DNA) at 4 h. However, the highest binding (120 pg/g DNA) was found between 24 and 72 h after the treatment. Dose response curves were linear for both protein and DNA binding. The binding of TCE metabolites to DNA was ca. 100-fold lower than to proteins when calculated per unit weight of macromolecules and when measured 2 h post-exposure. This study shows that TCE metabolites bind to DNA and proteins in a dose-dependent manner in liver, one of the target organs for its tumorigenicity. Thus, protein and DNA adduct formation should be considered as a factor in the tumorigenesis of TCE.

Inhibition of protein synthesis in liver and kidney of mice by bolesatine: mechanistic approaches to the mode of action at the molecular level

Protein synthesis was assayed in liver and kidney of mice treated with bolesatine, a toxic glycoprotein from the mushroom Boletus satanas (Lenz) which was previously shown to be an inhibitor of protein synthesis by cell-free systems in vitro and by cultured cell-lines. Protein synthesis in vivo (Swiss mice) is inhibited in a dose-dependent manner in liver and kidney. The mechanism of action does not appear to be due to RNA- N-glycosidase activity of bolesatine or a RNAase activity of this toxin on the ribosomal RNAs. Ribosomes do not appear to be damaged by pretreatment with bolesatine as judged by a poly(U) translation system. Thus bolesatine cannot be included in the group of protein synthesis inhibitors of plant origin known as ribosome-inactivating proteins (RIPs).

Co-induction by peroxisome proliferators of microsomal 1-acylglycerophosphocholine acyltransferase with peroxisomal β-oxidation in rat liver

Administration of clofibric acid, 2,2′-(decamethylenedithio)diethanol, di(2-ethylhexyl)phthalate or perfluorooctanoic acid to male rates increased markedly microsomal 1-acylglycerophosphocholine (a-acyl-GPC) acyltransferase in a dose-dependent manner in liver. Simultaneous administration of actinomycin D or cycloheximide completely abolished the increase in the enzyme activity. The treatment of rats with clofibric acid did not affect the rate of decay of 1-acyl-GPC acyltransferase. Regardless of a great difference in the chemical structures of the peroxisome proliferators, high correlation was observed between the induced activities of microsomal 1-acyl-GPC acyltransferase and peroxisomal β-oxidation. Stearoyl-CoA desaturase was induced by peroxisome proliferators in a dose-dependent manner; nevertheless, high correlation was not seen between the induced activities of desaturase and peroxisomal β-oxidation. Hormonal (adrenalectomy, diabetes, hyperthyroidism and hypothyroidism) and nutritional (starvation, starvation-refeeding, fat-free diet feeding and high-fat diet feeding) alterations hardly affected the activity of 1-acyl-GPC acyltransferase. The present results indicate that microsomal 1-acyl-GPC acyltransferase is a useful parameter responsive to the challenges by peroxisome proliferators and suggest that a similar regulatory mechanism operates for the inductions of microsomal 1-acyl-GPC acyltransferase and peroxisomal β-oxidation.