A novel method for preparation of animal models of liver damage: liver targeting of carbon tetrachloride in rats

Methyl Donor Ameliorates CCl4-Induced Nephrotoxicity by Inhibiting Oxidative Stress, Inflammation, and Fibrosis Through the Attenuation of Kidney Injury Molecule 1 and Neutrophil Gelatinase-Associated Lipocalin Expression

Carbon tetrachloride (CCl4), a volatile organic compound, is harmful to multi-organs, including the liver, lungs, muscles, and kidneys. Methyl donors, such as methionine, choline, betaine, and folic acid, are vital to one-carbon metabolism and have great potential to alleviate oxidative stress and inflammation, thus mitigating disease onset. Hence, the current study aims to examine the therapeutic effect of methyl donors against CCl4-induced nephrotoxicity. Nephrotoxicity was developed in male Sprague Dawley rats using CCl4 at a dose of 1 mL/kg (4-week model induction) twice a week via the intraperitoneal route. Thereafter, methyl donor treatments through oral gavage were given for the next 6 weeks with a continuation of CCl4 administration. Biochemical, oxidative stress parameters, histopathological, and qRT-PCR analyses were done at the completion of the 10-week. Biochemical analyses revealed that CCl4 induces nephrotoxicity, as evidenced by increased urea and creatinine levels and decreased albumin levels. These detrimental effects were significantly ameliorated by methyl donor treatment. Moreover, CCl4 decreased the antioxidant enzyme activity (superoxide dismutase; SOD and catalase; CAT) while increasing oxidative stress markers (malondialdehyde; MDA and nitrite). Methyl donor treatment effectively mitigated these oxidative changes. Histopathological analysis demonstrated the nephroprotective effect of methyl donors against CCl4-induced nephrotoxicity, showing reduced tissue damage and protection of renal architecture. At the molecular level, methyl donor treatment alleviated the CCl4-induced increase in kidney injury biomarkers (Kidney injury molecule 1; KIM-1 and Neutrophil gelatinase-associated lipocalin; NGAL), as well as inflammatory (IL-6 and TNF-α) and fibrosis-related genes (Acta-2 and TGF-β). In conclusion, our findings suggest that methyl donors possess anti-inflammatory and anti-fibrotic properties. They protect against CCl4-induced oxidative damage to renal cells, likely due to their reactive oxygen species scavenging capabilities and their ability to restore key early renal injury biomarkers (KIM-1 and NGAL). Methyl donors hold great promise as a cutting-edge therapy approach for preventing CCl4-induced nephrotoxicity.

Blunting p38 MAPKα and ERK1/2 activities by empagliflozin enhances the antifibrotic effect of metformin and augments its AMPK-induced NF-κB inactivation in mice intoxicated with carbon tetrachloride

AIM

Metformin and empagliflozin combined therapy may have complementary effects that go beyond the well-recognized targets of their monotherapy through AMPK activation. Therefore, the current study was designed to investigate for the first time the hepatoprotective effects of such combination therapy in the carbon tetrachloride (CCl₄)-induced hepatic fibrosis model in mice.

MATERIALS AND METHODS

Determination of liver enzymes and the liver content of oxidative stress parameters, and hydroxyproline were performed biochemically. ELISA was performed to measure PDGF-BB, TNF-α, TGF-β, TIMP-1, AMPK, p-mTOR, NF-κB P65 binding activity, p38 MAPKα, JNK1/2 and ERK1/2. Real-time qPCR was conducted to determine Col1a1 and α-SMA. In addition, histopathological examination using H&E and Masson's trichrome stain were performed for determination of histopathological changes.

KEY FINDINGS

Empagliflozin inhibited the activation of p38 MAPK and ERK1/2 and exhibited a weak AMPKα stimulation. On the other hand, metformin exerted a more robust stimulatory action on the AMPKα that was accompanied by a notable decrease in the NF-κB nuclear binding activity and a decline in the p-mTOR levels. Nevertheless, the effect of metformin on MAPK kinases was insignificant. Our results revealed that blunting p38 MAPKα and ERK1/2 activities by empagliflozin enhanced the antifibrotic effect of metformin and augmented its AMPK-induced NF-κB inactivation.

SIGNIFICANCE

As diabetes is one of the most common risk factors for liver fibrosis, the use of antidiabetic drugs is expected to improve therapeutic outcome. Therefore, metformin/empagliflozin combined therapy could be promising in preventing hepatic inflammation and fibrosis via exhibiting complementary effects particularly in diabetic patients.

Taurine and hesperidin rescues carbon tetrachloride-triggered testicular and kidney damage in rats via modulating oxidative stress and inflammation

AIMS

This study assessed the prophylactic or therapeutic effects of taurine (TR) and/or hesperidin (HES) on carbon tetrachloride (CCl₄) induced acute kidney and testicular injury in rats.

MAIN METHODS

Rats were randomly divided into nine experimental groups including control; corn oil; CCl₄; HES/CCl₄; TR/CCl₄; HES + TR/CCl₄; CCl₄/HES; CCl₄/TR; and CCl₄/HES + TR groups. CCl₄ was intraperitoneally injected with a single dose of 2 ml /kg b.w. HES and TR were orally gavaged twice weekly 100 mg/kg b.w. for four weeks. Kidney function, inflammatory response, sexual hormones, and oxidative stress indicators were assessed. Histomorphological and immune-histochemical studies of the inflammatory marker nuclear factor kappa (NF-κB) in renal and testicular tissues were performed.

KEY FINDINGS

The results showed that the TR and/or HES treatment significantly suppressed CCl₄ induced rise of urea, uric acid, potassium, and follicle-stimulating hormone levels. However, significant restoration of sodium, testosterone, and luteinizing hormone was apparent in CCl₄ exposed rats received HES and/or TR. Also, the HES and/or TR treatment significantly rescues CCl₄ induced oxidative stress and inflammation. Moreover, the HES and/or TR dosing significantly repaired the CCl₄ evoked altered renal and testicular architecture and suppressed NF-κB immunoexpression. Notably, alleviating CCl₄ induced renal and testicular damage was more effective in the prophylactic groups than the therapeutic groups. Also, most of the estimated parameters of the HES + TR group did not significantly vary from those of single TR or HES.

SIGNIFICANCE

In conclusion, HES or TR could efficiently guard against CCl₄ nephro-and reprotoxic effects, but both bioactive combinations afford only a limited synergistic outcome.

Increase in the systemic exposure of primary metabolites of Midazolam in rat arising from CYP inhibition or hepatic dysfunction

The main purpose of this study is to demonstrate the possibility of increase in the systemic exposure of drug metabolites by CYP-inhibition or acute hepatitis. Midazolam (MDZ) was used as a model substrate of CYP3A and 1-aminobenzotriazole (ABT) was used as a CYP-inhibitor. After oral pretreatment with ABT, MDZ was intravenously injected to rats and the plasma profiles of MDZ and its primary metabolites, 1'-hydroxy MDZ and 4-hydroxy MDZ, were observed. In the ABT-pretreatment rats, plasma AUCs of both metabolites were much larger than those in control rats, demonstrating a higher systemic exposure of metabolites under CYP-inhibited condition. Furthermore, kinetic analysis revealed that the amount of both metabolites entered into the systemic circulation increased significantly (about 5-times). Increases in the systemic exposure of the primary metabolites of MDZ were also observed in the acute hepatitis rats induced by CCl₄-pretreatment. As underlying mechanisms, it was speculated that ABT inhibited the subsequent metabolism of primary metabolites of MDZ in the hepatocytes and enhanced their release to the systemic circulation. In vitro study with rat liver microsomes supported this speculation. In conclusion, this study showed the complexity of PK profiles of drug metabolites, which might lead to new aspects on their safety issue.

In vivo antioxidant effect of aqueous root bark, stem bark and leaves extracts of Vitex doniana in CCl4 induced liver damage rats

OBJECTIVE

The antioxidant effects of aqueous root bark, stem bark and leaves of Vitex doniana (V. doniana) were evaluated in carbon tetrachloride (CCl4) induced liver damage and non induced liver damage albino rats.

METHODS

A total of 60 albino rats (36 induced liver damage and 24 non induced liver damage) were assigned into liver damage and non liver damage groups of 6 rats in a group. The animals in the CCl4 induced liver damage groups, were induced by intraperitoneal injection with a single dose of CCl4 (148 mg·ml(-1)·kg(-1) body weight) as a 1:1 (v/v) solution in olive oil and were fasted for 36 h before the subsequent treatment with aqueous root bark, stem bark and leaves extracts of V. doniana and vitamin E as standard drug (100 mg/kg body weighy per day) for 21 d, while the animals in the non induced groups were only treated with the daily oral administration of these extracts at the same dose. The administration of CCl4 was done once a week for a period of three weeks.

RESULTS

The liver of CCl4 induced not treated group showed that the induction with CCl4, significantly (P<0.05) increased thiobarbituric acid reactive substance (TBARS) and significantly (P<0.05) decreased superoxide dismutase (SOD) and catalase (CAT). However there was no significant (P>0.05) difference between TBARS, SOD and CAT in the liver of the induced treated groups and normal control group. In the kidney, TBARS showed no significant (P>0.05) difference between the normal and the induced groups, SOD was significantly (P<0.05) reduced in the CCl4 group compared to standard drug and normal control groups, CAT was significantly (P<0.05) increased in root and vitamin E groups when compared to induced not treated group. The studies also showed that when the extracts were administered to normal animals, there was no significant (P>0.05) change in the liver and kidney level of TBARS, SOD and CAT compared with the normal control except in the kidney of animals treated with stem extract where TBARS was significantly (P<0.05) lowered compared to control group.

CONCLUSION

The result of the present study suggests that application of V. doniana plant would play an important role in increasing the antioxidant effect and reducing the oxidative damage that formed both in liver and in kidney tissues. However stem bark has potential to improve renal function in normal rats.

Spleen-Selective Gene Transfer Following the Administration of Naked Plasmid DNA onto the Spleen Surface in Mice

The purpose of present study was to examine spleen-selective gene transfer following the administration of naked plasmid DNA (pDNA) onto the spleen surface in mice. Gene expression in the spleen and other tissues was evaluated based on firefly luciferase activity. Six hours after spleen surface instillation of naked pDNA, high gene expression in the spleen was observed. On the contrary, intravenous and intraperitoneal administration of naked pDNA resulted in no detectable gene expression. After instilling naked pDNA onto the spleen surface, gene expression in the spleen was significantly higher than those in other tissues. Six hours after instillation of naked pDNA onto the spleen surface, gene expression in the spleen reached the peak value, and thereafter decreased gradually. By utilizing a glass-made diffusion cell that is able to limit the contact dimension between the spleen surface and naked pDNA solution administered, site-specific gene expression in the spleen was found. This novel gene transfer method is expected to be a safe and effective strategy for DNA vaccine against serious infectious diseases and cancers.

Unilateral Lung-Selective Gene Transfer Following the Administration of Naked Plasmid DNA onto the Pulmonary Pleural Surface in Mice

The purpose of the present study was to examine unilateral lung-selective gene transfer following the administration of naked plasmid DNA (pDNA) onto the pulmonary pleural surface in mice. Naked pDNA was administered intravenously, intraperitoneally, and instilled onto the right pulmonary pleural surface. Four hours later, right pulmonary pleural surface instillation of naked pDNA resulted in high gene expression in the right lung. On the contrary, intravenous and intraperitoneal administration of naked pDNA resulted in no detectable gene expression. After instilling naked pDNA onto the right or left pulmonary pleural surface, gene expressions in the applied lung were significantly higher than those in the other lung and tissues. In addition, gene expressions were detected only in the intrathoracic tissues, not in the intraperitoneal tissues. Four hours after instillation of naked pDNA onto the right pulmonary pleural surface, gene expression in the right lung was the highest, and thereafter gene expression in the right lung decreased gradually. This novel gene transfer method is expected to be a safe and effective treatment against serious lung diseases.

Stomach-Selective Gene Transfer Following the Administration of Naked Plasmid DNA onto the Gastric Serosal Surface in Mice

The purpose of the present study was to achieve a stomach-selective gene transfer following the administration of naked plasmid DNA (pDNA) onto the gastric serosal surface in mice. Gene expression in the stomach and other tissues was evaluated by firefly luciferase activity. Six hours after gastric serosal surface instillation of naked pDNA, high gene expression in the stomach was observed. On the contrary, intravenous and intraperitoneal injection of naked pDNA exhibited no detectable gene expression. Following instillation of naked pDNA onto the gastric serosal surface, gene expression in the stomach was significantly higher than in other tissues. Gene expression in the stomach was highest 12 h after the instillation and thereafter decreased gradually. Utilizing a glass-made diffusion cell that is able to limit the contact dimension between the gastric serosal surface and the naked pDNA solution administered, site-specific gene expression in the stomach was achieved. This novel gene transfer method is expected to be a safe and effective treatment against serious stomach diseases.

Reduction of carbon tetrachloride-induced nephropathy by melatonin administration

The aim of this study was to investigate possible protective effects of melatonin on carbon tetrachloride (CCl4)-induced renal damage in rats. A total of 24 animals were divided into three equal groups: the control rats received pure olive oil subcutaneously, rats in the second group were injected with CCl4 (0.5 ml kg-1, s.c. in olive oil) and rats in the third group were injected with CCl4 (0.5 ml kg-1) plus melatonin (25 mg kg-1, s.c. in 10% ethanol) every other day for 1 month. At the end of the experimental period, the animals were sacrificed and blood samples were collected. The kidneys were removed and weighed. Urea and creatinine levels were determined in blood samples. Histopathological examination of the kidney was performed using light microscopic methods. Administration of CCl4 significantly increased relative kidney weight (g per 100 g body weight) and decreased serum urea levels compared to controls (p<0.01). Melatonin treatment significantly (p<0.01) reduced relative kidney weight, and it produced a statistically equal (p=0.268) relative weight with the kidneys of control rats. CCl4 administration alone also caused histopathologically prominent damage in the kidney compared to the control group. Glomerular and tubular degeneration, interstitial mononuclear cell infiltration and fibrosis, vascular congestion around the tubules, and interstitial haemorrhage in perivascular areas were observed in the renal cortex and cortico-medullary border. However, the affect of CCl4 on the medulla was limited. Melatonin provided protection against CCl4-induced renal toxicity as was evident by histopathological evaluation. In view of the present findings, it is suggested that melatonin protects kidneys against CCl4 toxicity.

Pharmacokinetic Behavior of Micafungin in Rats with Carbon Tetrachloride-Induced Acute Hepatic Failure

We examined the pharmacokinetic behavior of micafungin, a novel antifungal agent, in rats receiving carbon tetrachloride (CCl4) at a single dose of 2.5 ml/kg. There was no significant change in the total clearance (CL(tot)) in CCl4-treated rats, while the steady-state volume of distribution (Vd(ss)) was significantly increased by CCl4 treatment. Alteration in the serum unbound fraction of micafungin after CCl4 treatment was unlikely in light of the serum albumin, bilirubin, creatinine, and urea nitrogen. The increased Vd(ss) was attributable to augmentation in the accessibility of micafungin to peripheral tissue without impairment of the intrinsic clearance, because slight enhancement of the tissue distribution of micafungin was confirmed following CCl4 treatment.

Unilateral Kidney-Selective Gene Transfer Following the Administration of Naked Plasmid DNA to the Kidney Surface in Mice

We developed a gene transfer following the administration of naked plasmid DNA (pDNA) to the kidney surface in mice, and found that the luciferase levels produced in the applied kidney were significantly higher than those produced in another kidney. In contrast, stable renal gene expression was not observed in the case of intraperitoneal or intravenous administration of pDNA. The level of gene expression after instillation of pDNA to the kidney surface reached maximum at 12 h and gradually diminished thereafter. The production of luciferase was saturated at 5 microg of pDNA, and was not affected by instillation volume. Furthermore, pDNA uptake from the kidney surface was proved by in situ experiments using a glass-made diffusion cell. We demonstrated a novel unilateral kidney-selective gene transfer following the administration of naked pDNA to the kidney surface in mice.

Pharmacokinetics of Phenol Red in Rat Models of Liver Damage Prepared by Liver Targeting of Carbon Tetrachloride

Animal models prepared by treatment with carbon tetrachloride (CCl(4)) have been used to examine drug disposition in hepatic disorder. However, previous studies demonstrated that systemic administration of CCl(4) impaired not only hepatic but also renal function. We recently reported that application of CCl(4) to the rat liver surface produced hepatic damage without impairing renal function. In the present study, we examined the pharmacokinetics of phenol red in our developed rat model. The rats treated with CCl(4) by liver surface application exhibited decreases in the biliary clearance of phenol red in comparison with normal rats from 0.54+/-0.03 to 0.31+/-0.06 ml/min, suggesting hepatic damage. In these rats, the renal clearance of phenol red did not decrease (0.50+/-0.16 ml/min vs. 0.46+/-0.07 ml/min in normal rats). On the other hand, oral and intraperitoneal treatments with CCl(4) reduced not only the biliary clearance of phenol red (0.34+/-0.03 ml/min in p.o. treated rats, 0.18+/-0.01 ml/min in i.p. treated rats) but also the renal clearance (0.26+/-0.05 ml/min in p.o. treated rats, 0.18+/-0.06 ml/min in i.p. treated rats) as compared with normal rats. These findings indicate that the rat model of liver damage prepared by liver surface application of CCl(4) is useful to investigate the effects of hepatic disorder on the pharmacokinetics of drugs.

[Development of drug delivery system based on a new administration route for targeting to the specific region in the liver]

Development of drug delivery systems to achieve site-specific delivery or prolonged retention in the circulation has attracted attention, because new types of drugs are expected to be created with advances in life science and biotechnology such as the Human Genome Project. We have tried to develop a new administration route for drug targeting to the liver, since drug administration by the intravenous and oral routes makes it difficult to achieve a local site of action in the liver. Although direct application to the liver surface should result in local drug distribution, drug absorption from the liver surface has not been reported in the literature. Therefore we analyzed the absorption mechanism of several organic anions and dextrans with different molecular weights as model drugs, after application to the rat liver surface in vivo, employing a cylindrical diffusion cell. Every compound appeared gradually in the plasma, followed by excretion into the bile and/or urine, indicating the possibility of drug absorption from the liver surface. A specific transport system might not be involved in the absorption process from the liver surface, because the effect of dose and transport inhibitors on the absorption was not recognized. In addition, molecular weight was found to be a determining factor in absorption from the liver surface. The targeting efficacy was considerably enhanced by application to the liver surface, as compared with intravenous administration. Moreover, we have identified important physicochemical and pharmaceutical factors determining the absorption rate of a drug from the liver surface for clinical use. Consequently, drug application to the liver surface could improve availability in the desired site of a new drug such as bioactive compounds and genomic medicines, by combination with appropriate chemical and pharmaceutical formulation modifications.