Therapeutic potential of ramipril, losartan, and spironolactone against sepsis-associated liver tissue injury induced by cecal ligation and puncture in rats

OBJECTIVE

Sepsis-associated liver injury is responsible for the high morbidity and mortality rates seen with septic shock. Activation of the renin-angiotensin-aldosterone system (RAAS) is an essential counteractive mechanism during the hypotensive phase of sepsis; however, excessive activation is associated with exaggerated pro-oxidant and inflammatory response, which aggravates organ damage. This study aimed to evaluate the effect of RAAS inhibition on sepsis-induced liver damage.

MATERIALS AND METHODS

The cecal ligation and puncture (CLP) model was employed as a model of sepsis. Rats were divided into five groups: sham-operated, vehicle-treated septic rats, septic rats treated with ramipril in a dose of 10 mg/kg, septic rats treated with losartan in a dose of 20 mg/kg, and finally septic rats treated with spironolactone in a dose of 25 mg/kg. Rats received the treatment one hour after induction. Twenty-four hours later, rats were euthanized, and serum samples and liver tissue were collected to evaluate liver function and hepatic oxidative, anti-oxidative, inflammatory, and apoptotic markers. The microscopic integrity of the hepatic tissue was also assessed.

RESULTS

The results of our study showed that all the treatments used ameliorated sepsis-induced liver injury. This was reflected by improved liver function parameters and histopathological appearance of liver tissue. Treatment with ramipril, losartan, or spironolactone reduced tissue malondialdehyde (MDA), nitric oxide, activated caspase-3, and TNF-α. Moreover, these drugs increased hepatic reduced-glutathione (GSH) levels, superoxide dismutase (SOD) activity, and proliferating cell nuclear antigen (PCNA) expression.

CONCLUSIONS

Administration of ramipril, losartan, or spironolactone after CLP produced a hepatoprotective effect in rats, possibly by reducing oxidative stress, inflammation, and apoptosis.

Anti-inflammatory effects of the chloroform extract of Pulicaria guestii ameliorated the neutrophil infiltration and nitric oxide generation in rats

Pulicaria guestii Rech.f. & Rawi is a fragrant, perennial herb, which grows wild, west of Al-Madinah, Saudi Arabia. Several reports were published on the anti-inflammatory activity of the sesquiterpene lactones, phenolics and flavonoids, which constitute the main active constituents of the members of the genus Pulicaria. The present study was designed to explore the potential anti-inflammatory effect of P. guestii in several experimental models. The methanol extract of the dried aerial parts of P. guestii was extracted with petroleum ether, chloroform and n-butanol. The chloroform extract was analysed on TLC and examined under UV and visible light in presence of AlCl(3) spray. The free radical scavenging activity and the total phenolic content in the CHCl(3) extract were estimated. The crude methanol extract and the CHCl(3) fraction were examined against carrageenin-induced paw edema and ear edema induced by croton oil application. The crude methanolic extract significantly reduced carrageenin-induced rat paw edema. After fractionation, the chloroform fraction caused significant reduction in carrageenin-induced rat paw edema in addition to diminishing prostaglandin E(2) (PGE(2)) in the inflammatory exudates. Topical application of chloroform fraction significantly reduced rat ear edema induced by croton oil application. In the same model, chloroform fraction reduced neutrophil infiltration, as indicated by the significant decrease in myeloperoxidase activity, and ameliorated histopathological changes induced by croton oil application. In lipopolysaccharide-induced inflammation in rat air pouch, chloroform fraction significantly reduced the nitric oxide level and tumor necrosis factor-α release. In conclusion, the chloroform fraction of P. guestii extract possesses anti-inflammatory activity in several experimental models. Further investigations are needed to identify the active constituents responsible for this anti-inflammatory activity.

Chloroacetonitrile induces intrauterine growth restriction and musculoskeletal toxicity in fetal mouse

Chloroacetonitrile (CAN) is a by-product of chlorination of drinking water. Epidemiological studies indicate that it might present a hazard to human health. The present study was designed to investigate the potential adverse effects of intrauterine exposure to CAN on fetal body weight and development of the musculoskeletal system in mice. At gestation day 6, pregnant mice were given CAN (12.5, 25, or 50 mg/kg/day) till gestation day 18. Uteri were then examined and live fetuses were collected, weighed, and evaluated for any malformations. High doses of CAN (50 mg/kg) significantly elevated fetal anomalies and reduced fetal viability. Chloroacetonitrile at a dose of 25 mg/kg did not affect fetal viability and significantly reduced fetal body weight. Subsequent experimentation was performed using this dose level. Histological examination of fetal axial skeleton indicated that CAN resulted in delayed appearance of endochondral ossification centers, widening of the vertebrae, and destruction of the calcified zone. In addition, the skeletal muscle fibers were markedly distorted, were small in size, and were widely separated by connective tissue. Both connective tissue perimysium and endomysium were less cellular compared with control sections. The histological findings were further confirmed by assessing the morphometric changes. Ratios of calcified cartilage to non-calcified cartilage areas in both control and CAN-exposed groups were determined. Also, skeletal muscle fiber diameter of CAN-exposed fetuses was significantly decreased compared with control group. In conclusion, intrauterine exposure to low levels of CAN decreases fetal body weight and induces malformations in the musculoskeletal system in mice.

The influence of thymoquinone on doxorubicin-induced hyperlipidemic nephropathy in rats

The effect of thymoquinone (TQ), the main constituent of the volatile oil of Nigella sativa seeds, on the nephropathy and oxidative stress induced by doxorubicin (DOX) in rats was investigated. A single intravenous injection of DOX (6 mg/kg) induced a severe nephrotic syndrome (after 5 weeks) associated with hypoalbuminemia, hypoproteinemia, elevated serum urea, hyperlipidemia, and a high urinary excretion of protein, albumin and N-acetyl-beta-D-glucosaminidase (NAG). In the kidney, DOX induced a significant increase in total triglycerides (TG), total cholesterol (TC), and lipid peroxides and a significant decrease in non-protein sulfhydryl (NPSH) content and catalase (CAT) activity. Treatment of rats with TQ (10 mg/kg per day) supplemented with the drinking water for 5 days before DOX, and daily thereafter, significantly lowered serum urea, TG, and TC. Similarly, TG, TC and lipid peroxides in the kidneys of TQ-treated rats were decreased significantly compared with DOX alone. Moreover, NPSH content and CAT activity in the kidneys of TQ-treated DOX group were significantly elevated compared with DOX alone. Treatment with TQ significantly suppressed DOX-induced proteinuria, albuminuria, and urinary excretion of NAG. The results confirm the involvement of free radicals in the pathogenesis of nephropathy induced by DOX. Likewise, the study demonstrates the high antioxidant potential of TQ and its marked effect on the suppression of DOX-induced nephropathy. The data suggest that TQ might be applicable as a protective agent for proteinuria and hyperlipidemia associated with nephrotic syndrome.

Differential alteration of cisplatin cytotoxicity and myelotoxicity by the paclitaxel vehicle cremophor EL

Cremophor EL (CR), the paclitaxel vehicle, has previously been reported to alter the pharmacokinetics and/or pharmacodynamics of some anticancer drugs including paclitaxel. Several experimental and clinical studies suggested that cisplatin (CDDP) in combination with paclitaxel results in less hematological toxicity than anticipated. To reveal the role of CR in this important pharmacological interaction, we evaluated the interaction of CR with CDDP in vitro and in vivo using experimental Ehrlich ascites carcinoma (EAC) tumor. CR (1 microg/ml) significantly enhanced the in vitro cytotoxicity of CDDP in cultured EAC cells. This enhancement was not associated with a parallel increase in CDDP cellular uptake. In tumor-bearing mice, CR (2.5 ml/kg, i.v.) given in combination with CDDP (7 mg/kg, i.v.) did not significantly change CDDP pharmacokinetics, antitumor activity or nephrotoxicity. On the other hand, CDDP-induced hematological toxicity was significantly reduced by CR. This protective effect was related to CR-induced inhibition of cellular CDDP accumulation in bone marrow. This study presents evidence that CR may play an important role in the pharmacological interaction between CDDP and paclitaxel. The present data may suggest formulation of CDDP with CR for systemic treatment. Further studies are yet necessary to establish the clinical value of CR as a modifier for CDDP therapeutic index.

Chloroacetonitrile-induced toxicity and oxidative stress in rat gastric epithelial cells

Chloroacetonitrile (CAN), is a disinfectant by-product of chlorination of drinking water. Epidemiological studies indicate that exposure to CAN via drinking water might present a potential hazard to human health. The objective of the present work was to investigate the cytotoxic effects as well as the oxidative stress induced by CAN in cultured rat gastric epithelial cells (GECs). GECs were exposed in vitro to different concentrations of CAN (5-40 microm) for 60 min. Also, GECs were incubated with CAN (10 microm) for different time intervals extending to 180 min. Cytotoxicity was determined by assessing cell viability and lactate dehydrogenase (LDH) release, glutathione (GSH) level and lipid peroxidation as indicated by malondialdehyde (MDA) production. Exposure of GECs CAN (10 microm) for 60 min caused a 50% decrease in cell viability and induced an eightfold increase of LDH leakage. In the same experiment, CAN caused a decrease in cellular GSH content to approximately 50% and significantly enhanced MDA accumulation (approx. sevenfold). These toxic responses to CAN were dependent on both concentration and duration of exposure to CAN. There was a good correlation between LDH release and GSH depletion (r =0.96, P<0.05). Treatment of GECs with 5 m mN -acetyl- l -cysteine (NAC) prior to exposure to CAN afforded some degree of protection as indicated by a significant decrease in the LDH leakage (32% of total leakage) and lipid peroxidation (54%) as compared to CAN alone-treated cells. Also, pretreatment of GECs with vitamin C (1 m m) or vitamin E (10 microm) significantly inhibited LDH leakage (20 and 36% of total leakage, respectively). Preincubation with 1 m m desferroxiamine (DFO), a ferric iron chelator, or 10 microm phenanthroline (PHE), a ferrous iron chelator, diminished CAN-induced LDH leakage by 16 and 21% of total leakage, respectively and MDA production by 40 and 44%, respectively. In conclusion, our results suggest that CAN has a potential cytotoxic effect in rat GECs; and thiol group-donors, antioxidants and iron chelators can play a critical role against CAN-induced cellular damage.

Renal metabolism of acrylonitrile to cyanide: in vitro studies

Acrylonitrile (VCN) is a widely used industrial chemical. The present work examines the mechanism of its renal toxicity. In renal centrifugal fractions from Sprague-Dawley rats, the metabolism of VCN to cyanide (CN(-)) was highest in the microsomal fraction and required a NADPH-generating system in the presence of magnesium ions for maximum activity. This biotransformation of VCN to CN(-)was characterised with respect to time (15 min), microsomal protein concentration (3 mg ml(-1)), pH (7.5) and temperature (37 degrees C). The V(max)of the reaction was 118.2 pmol CN(-)mg(-1)protein min(-1)and K(m)was 160.2 micromol VCN. Activation of VCN to CN(-)was markedly increased in microsomes obtained from phenobarbital (PB), ethanol, 4-methylpyrazole and 3-methylcholanthrene-treated rats by 161.5, 89.6, 71.0 and 50.2%, respectively. Addition of SKF 525-A (5x10(-4)m) or benzimidazole (2 m m) to the incubation mixtures significantly inhibited VCN metabolism by 66.6 and 78.8%, respectively. VCN metabolism to CN(-)was enhanced significantly by the addition of 10 m m of glutathione (GSH), l -cysteine, d -penicillamine, cysteamine or 2-mercaptoethanol to 389.5, 886.5, 611. 1, 145.5 and 384.0% of control, respectively. These findings indicate that VCN is metabolised in the kidney via cytochrome P-450-dependent mixed function oxidase system. 1999 Academic Press.

Protective effects of vitamin e and probucol against gentamicin-induced nephrotoxicity in rats

Gentamicin (GM) is widely used as a bactericidal agent for the treatment of severe gram negative infections, however, its clinical use is partially limited due to its nephrotoxicity. Recent evidence suggests a role of reactive oxygen metabolites in GM nephrotoxicity. The present study was designed to investigate a possible potential protective role of vitamin E and/or probucol against GM nephrotoxicity. GM was administered to rats in a single dose of (150 mg kg(-1)i.p.), while vitamin E (250 mg kg(-1)i.m.) and/or probucol (60 mg kg(-1)i.m.) were given once daily for 3 consecutive days prior to GM administration. GM-induced nephrotoxicity was evidenced by marked elevations in serum urea and creatinine levels, urinary activity of N-acetyl-beta- d -glucosaminidase (NAG) and gamma-glutamyl-transferase (gamma-GT). Also, GM caused significant increases in kidney content of malondialdehyde (MDA), and significant decreases in kidney content of reduced non-protein sulphydryls (NPSH) and superoxide dismutase (SOD) activity. Vitamin E pretreatment significantly lowered the elevated serum urea and creatinine levels, and urinary activity of NAG and gamma-GT. In addition, vitamin E ameliorated the rise in renal content of MDA and enhanced the renal NPSH content as well as SOD activity. Similarly, probucol significantly inhibited the elevations in urea and creatinine levels and enhanced renal NPSH content and SOD activity. Simultaneous use of vitamin E and probucol was more effective in mitigating disturbances in the assessed parameters. The present work indicates that, due to their antioxidant activity, vitamin E and probucol have potential protective effects against GM nephrotoxicity.

In-vitro testicular bioactivation of acrylonitrile

The present work examines the mechanism of testicular toxicity of acrylonitrile. In testicular centrifugal fractions from Sprague Dawley rats, the metabolism of VCN to cyanide (CN-) was highest in the microsomal fraction and required NADPH for maximum activity. This biotransformation of VCN to CN- was characterized with respect to time (30 min), microsomal protein concentration (1.5 mg ml(-1)), pH (7.5) and temperature (37 degrees C). The V(max) of the reaction was 65.1 pmol CN- mg protein(-1) min(-1) and K(m) was 88.6 micromol VCN. Flushing the microsomes with carbon monoxide (CO)(4:1, CO/O2 v/v), addition of benzimidazole (1 mM) or addition of SKF 525-A (5x10(-4) M) to incubation mixtures significantly inhibited VCN metabolism by 49%, 54% and 37.4% respectively. Activation of VCN to CN- was markedly increased in microsomes obtained from phenobarbital (PB)-treated rats (128.2%). Addition of glutathione (GSH), L-cysteine, D-penicillamine or 2-mercaptoethanol significantly enhanced the release of CN- from VCN 126%, 247%, 202% and 129% of the control value respectively. These findings indicate that VCN is metabolized in the testis via cytochrome P-450 dependent mixed function oxidase system.