Biochemical changes induced in liver and serum of diplodiatoxin (Stenocarpella maydis) treated male and female rats

Present study was conducted to investigate the acute and sub-acute toxic effect of diplodiatoxin with special reference to biochemical membrane bound enzymes like aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and RBC acetylcholinesterase (AChE) in male and female rats. For acute study, rats were treated with a single oral dose of 5.7 mg/kg of diplodiatoxin, whereas for sub-acute study, the rats received 0.27 mg/kg/day for 21 days. Acute and sub-acute diplodiatoxin treatment caused loss in body weight and feed intake along with symptoms including irritation, dullness, tremors and convulsions. Diplodiatoxin caused a significant increase in serum ASAT and ALAT and a decrease in activity in the liver in both acute and sub-acute studies. This compound also significantly inhibited RBC AChE. Sexual dimorphism was observed when male rats were compared with female rats (p < 0.05). The enzyme alterations observed in the affected enzymes recovered to the normal levels by day 7 post treatment (withdrawal study) in both acute and sub-acute treated rats. A negative correlation was observed with regard to these enzymes when serum was compared with liver. These enzyme profiles show increases in serum with parallel decrease in liver, indicating necrosis of liver. These results suggest that diplodiatoxin has potential to affect hepatic end-points.     

Effects of Vepacide (Azadirachta indica) on aspartate and alanine aminotransferase profiles in a subchronic study with rats

The aim of this study was to ascertain the long-term effects of Vepacide, a neem-based pesticide on biochemical profiles. Albino Wistar rats were treated orally with 80 (low), 160 (medium) and 320 mg/kg (high) doses of Vepacide in coconut oil for 90 days. Control rats received the same volume of the vehicle. Vepacide caused increase of aspartate and alanine aminotransferase in serum, kidney and lung, and these enzymes decreased in liver in both male and female rats when measured after 45 and 90 days of treatment. The two-way analysis of variance (ANOVA) showed that the alterations in these enzymes were dose- and time-dependent. Sexual dimorphism was observed when male rats were compared with female rats (Student t-test at P< 0.05). Positive correlation was observed with regard to these enzymes between serum, kidney and lung, whereas in the case of serum and liver, a negative correlation was recorded. These enzyme profiles elucidate that they increased in serum with simultaneous decrease in liver, indicating necrosis of liver, whereas in other tissues, the level of enzymes increased, showing an adaptive mechanism due to the chemical stress. The affected enzymes were recovered to normal conditions after 28 days of post-treatment (withdrawal study). Due to the Vepacide treatment, lung was more affected followed by liver and kidney. This study has indicated that these enzymes could be useful as biomarkers for the insult of any toxicant. Besides, they can also help in predictive toxicology.     

The effect of chlorpromazine and carbamazepine on diagnostically relevant liver enzymes

No interactions related to the analytical method were observed between chlorpromazine (1) or carbamazepine (2) and activities of alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), glutamate dehydrogenase (GLDH) or lactate dehydrogenase (LDH). With respect to its cytotoxic potential 1 in cultures of isolated rat hepatocytes increased markedly the release of enzymes into the culture medium, whereas the overall activities of the enzymes were not influenced. 2 in cultured hepatocytes caused no significant effects on the activities of the enzymes investigated. Besides the investigation of methodically related interactions in pooled human serum the methodic procedure including the use of cultures of isolated hepatocytes allows to study also pharmacologically and toxicologically related interactions between drugs and diagnostically relevant liver enzymes.     

Trimetazidine ameliorates the hepatic injury associated with ischaemia-reperfusion in rats.

Ischaemia-reperfusion induces structural and functional damage to hepatocytes. The purpose of this study was to evaluate the protective effect of trimetazidine, an anti- ischaemic drug, in a rat liver model of ischaemia-reperfusion. Male Wistar rats were divided into groups pretreated with different doses of trimetazidine (1, 5, 10 or 20 mg kg-1 day-1) or saline for 7 days. Liver ischaemia was induced for 120 min and blood reflow was subsequently restored for 30, 60, 90 or 120 min. The activities of alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) as well as the bile flow and the liver ATP content were determined. Ischaemia-reperfusion induced major alterations of hepatic functions involving increases of ASAT and ALAT activities, a drop of ATP content and a sharp decrease in bile flow. Trimetazidine pretreatment reduced the liver injury. Indeed, it lowered the increase in ALAT and ASAT activities observed immediately after reperfusion and maintained higher concentrations of hepatic ATP. Simultaneously, bile flow was increased. These effects were dose-dependent and 5 mg kg-1 day-1 seemed to be the lowest effective dose. In this experimental model trimetazidine pretreatment reduced the liver damage induced by ischaemia-reperfusion. Our data suggest that trimetazidine may be a useful drug in liver surgery to prevent ischaemia-reperfusion injury.     

Observations of alanine aminotransferase and aspartate aminotransferase in THRIVE studies treated orally with ximelagatran

Treatment of acute venous thromboembolism (VTE) and prophylaxis of recurrent events has been investigated in the THRIVE (THRombin Inhibitor in Venous Thrombe Embolism) Treatment and the THRIVE III trial using the oral direct thrombin inhibitor ximelagatran. Alanine aminotransferase (ALAT) increased in 9.6% and 6.4% of patients in the THRIVE Treatment and THRIVE III trials, respectively. The authors analysed the time course of the ALAT and in additionally of aspartate aminotransferase (ASAT) in blood from 52 and 23 patients participating in the THRIVE Treatment and the THRIVE III trials in Germany. Analysis of variance for repeated measures and t test were performed. In the THRIVE Treatment trial, ALAT was significantly higher at week 2 for enoxaparin/warfarin (p => .0039, t test) and at months 3 and 6 for ximelagatran (p = .0453, p = .0014, respectively). ASAT and ASAT/ALAT ratio values did not increase and not differ for both groups. In the THRIVE III trial, ALAT and ASAT did not increase and did not differ compared to the comparator placebo. 2 x 36 mg Ximelagatran, induced higher ALAT values at months 3 and 6 compared to 2 x 24 mg ximelagatran (p = .0105, p = .0063, respectively). ASAT did not differ between the two doses of ximelagatran. The ASAT/ALAT ratios were lower at week 2 for enoxaparin/warfarin (t-test, p = .0032) and at month 3 and 6 for 2 x 36 mg versus warfarin or 2 x 24 mg Ximelagatran (p between .0187 and .0002). The authors conclude that ALAT increases dose dependently during therapy with ximelagatran. The less frequent and lower increase of ASAT values compared to ALAT values indicates a nontoxic effect of ximelagatran on liver cells.     

Novel Sources of Mammalian C-S Lyase Activity

The C-S lysis of L-cysteine conjugates is one biotransformation pathway which is responsible for the generation of mutagenic and cytotoxic metabolic species. Thirteen cysteine S-conjugates were synthesized in our laboratories and incubated with aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) enzymes from porcine heart tissue. The C-S lyase (CSL) activity for each enzyme-substrate combination was determined. ASAT and ALAT were shown to exhibit CSL activity and it was also demonstrated that this activity was inhibited in the presence of the pyridoxal phosphate-dependent enzyme inhibitor amino(oxyacetic acid) confirming the pyridoxal phosphate-dependent mechanism by which C-S lysis is known to take place. This finding has potentially important implications for the risk assessment of compounds which produce L-cysteine conjugates during their biotransformation.     

Hepatotoxicity following nevirapine-containing regimens in HIV-1-infected individuals.

To determine the incidence of hepatotoxicity and to investigate whether plasma concentrations of nevirapine, in addition to other risk factors, could predict hepatotoxicity during treatment with nevirapine-containing regimens, we conducted a retrospective analysis with data from 174 individuals infected with human immunodeficiency virus-1 (HIV-1). During regular visits to the clinic, blood samples were collected for the determination of nevirapine plasma concentrations and clinical chemistry parameters including liver enzymes (LEs) and total bilirubin (TBR). Severe hepatotoxicity was defined as a grade > or =3 elevation in at least one of the tested LEs or TBR levels while on therapy. Analysis of predictive factors was focused on increases in aspartate aminotransferase (ASAT) and/or alanine aminotransferase (ALAT) to grade > or =2. Grade > or =3 elevation developed with an incidence of 0.15 per patient year (PY); only 3.4% of the patients developed grade > or =3 values for ASAT and/or ALAT (incidence 0.03 per PY). We found that patients who use a protease inhibitor (PI) in a nevirapine-containing regimen and patients who have chronic hepatitis B (HBV) infection are at a higher risk for the development of increases in ASAT and/or ALAT to grade > or =2. In contrast, the plasma concentration of nevirapine does not appear to be a predictive factor in this study population.     

Fumonisin B1-induced DNA damage in rat liver and spleen: effects of pretreatment with coenzyme Q10, L-carnitine, alpha-tocopherol and selenium.

Active oxygen radical species are reported to cause organ damage. This study was designed to determine whether oxidative stress contributed to the initiation or progression of hepatic and splenic cell DNA damage induced by fumonisin B1 (FB1) in rats. Another aim was to investigate the protective effects of the antioxidants coenzyme Q10 (CoQ10), L-carnitine, vitamin E (alpha-tocopherol) and selenium against DNA damage in the liver and spleen of rats treated with FB1. Fasted rats were injected intravenously with a single dose of fumonisin B1 at 1.55 mg kg-1 body wt. into the tail vein. Treatment with FB1 led to splenic and hepatic DNA fragmentation in 85% of the test animals. DNA fragmentation was investigated as a critical event in toxic cell death by testing total Ca2+ in liver. FB1 administration caused total Ca2+ in liver to increase within 4 h (204% of control). Measurement of liver enzyme activities showed an increase in aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT). FB1 also markedly decreased splenic and hepatic glutathione (GSH) levels. Pretreatment with CoQ10 (30 mg CoQ10 kg-1 diet) together with L-carnitine (2.8 mg carnitine kg-1 diet), alpha-tocopherol (30 IU vitamin E kg-1 diet) and selenium (1 mg selenium as sodium selenite kg-1 diet), decreased DNA damage and the activities of Ca2+, ASAT and ALAT in the liver. On the other hand, the level of GSH was slightly increased. The CoQ10 alone did not significantly protect against toxic cell death and glutathione depletion caused by FB1. Oxidative damage caused by FB1 may be one of the underlining mechanisms of FB1-induced cell injury and DNA damage.     

Early biochemical and histological changes in rats exposed to a single injection of thioacetamide

Liver injury was induced by one subcutaneous administration of thioacetamide (200 mg/kg b.wt.) and studied 24 and 48 hrs later. Levels of aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) increased after 24 and 48 hrs. The lysosomal enzymes beta-hexosaminidase (beta-NAG) and beta-glucuronidase (beta-GLU) increased significantly after 24 hrs, while the level of beta-GLU returned to normal after 48 hrs, but the activity of beta-NAG remained significantly high even after 48 hrs. Histopathological examination showed necrotic hepatocytes around the central vein with infiltration of macrophages, neutrophils and eosinophils. The plasma zinc level decreased after 24 hrs and returned to normal after 48 hrs. Liver zinc content increased simultaneously at 24 hrs, returning to normal after 48 hrs. No alterations of plasma copper were observed after 24 and 48 hrs. Copper content of the liver increased significantly after 24 and 48 hrs. The present study thus shows that one dose of thioacetamide results in profound liver injury and supplementation of zinc prior to and simultaneously with thioacetamide normalized plasma zinc, increased liver zinc content and reduced the increase of beta-NAG, but did not influence the histological changes.     

Dietary zinc deficiency induced-changes in the activity of enzymes and the levels of free radicals,lipids and protein electrophoretic behavior in growing rats

Zinc (Zn) is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth and reproduction. The present study was conducted to investigate the effects of adequate Zn level (38 mg/kg diet, as a control) and two low levels that create Zn deficiencies (19 mg/kg diet, 1/2 of the control and 3.8 mg/kg diet, 1/10 of the control) in growing male and female rats for 10 weeks. To evaluate the effects of these levels, the concentrations of thiobarbituric acid-reactive substances (TBARS), biochemical parameters and protein pattern were studied. Lipid peroxidation in liver, brain and testes of rats fed Zn-deficient diet was indicated by increased TBARS. Serum, liver, brain and testes glutathione S-transferase (GST) activities were significantly (P<0.05) increased in Zn-deficient rats, the effect was pronounced in rats fed the lowest level of Zn (1/10 of control). The activity of lactate dehydrogenase (LDH) was significantly (P<0.05) increased in liver, brain and testes, but decreased in serum in a dose-dependent manner. Zinc deficiency increased (P<0.05) liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in a dose-dependent manner, while there was no effect on the activity of these enzymes in testes. Zinc deficiency resulted in a significant (P<0.05) decrease in the activity of alkaline phosphatase (AlP) in serum and liver in a dose-dependent manner, but no effect in testes was found. The activity of acid phosphatase (AcP) was not affected in serum, liver and testes. Zn-deficient rats had higher liver concentrations of total lipids (TL), cholesterol, triglyceride (TG), and low density lipoprotein (LDL), while high density lipoprotein (HDL) was significantly (P<0.05) declined in a dose-dependent manner. Brain and serum acetylcholinesterase (AChE) activities were, however, not affected (P<0.05) by Zn deficiency. Protein content in liver, brain and testes showed a significant (P<0.05) decrease in rats fed the lowest level of Zn (1/10 of control). Polyacrylamide gel electrophoresis (native-PAGE) of serum proteins revealed that the intensity of immunoglobulins, serum albumin as well as several peptide bands were decreased in rats fed 1/2 or 1/10 of Zn adequate, i.e. their synthesis was affected and it was pronounced with the lowest level of Zn deficiency (1/10 of control). However, no clear effect on the transferrin was observed in both cases compared to controls. From the results of this study it can be concluded that Zn deficiency exerts numerous alterations in the studied biochemical parameters, protein pattern, and increased lipid peroxidation.     

Formation of GSH-derivatives as a pathway for inactive intermediates in vinylidene chloride-treated rats

The two conjugates, S-[N-(2-hydroxyethyl)carbamoylmethyl]glutathione (GSAAE), and its corresponding mercapturic derivative N-acetyl-S-[N-(2-hydroxyethyl)carbamoylmethyl]cysteine (NCySAAE) were administered to fasted Sprague-Dawley rats as putative metabolites of vinylidene chloride (VDC). Methylthioacetylaminoethanol (MAAE) was identified in the urine of GSAAE- or NCySAAE-treated rats (0.5–2.0 mmol/kg i.p.), as well as in the urine of VDC-treated rats (0.5–2.0 mmol/kg p.o.). The effects of VDC, GSAAE and NCySAAE on the kidney and liver were also examined using aspartate aminotransferase (ASAT), N-acetyl-β-d-glucosaminidase (NAG) and β₂-microglobulin (β₂-m) as urinary parameters of nephrotoxicity, and glutamate dehydrogenase (GLDH), sorbitol dehydrogenase (SDH) and alanine aminotransferase (ALAT) as serum parameters of hepatotoxicity. Unlike treatment with VDC, treatment with both GSAAE and NCySAAE failed to cause kidney and liver toxicity. The results support the hypothesis that MAAE originates from the formation of GSAAE and further metabolization to NCySAAE, and that MAAE excretion does not reveal a pathway of reactive intermediates.     

Acid and alkaline phosphatase activities in a novel phosphorothionate (RPR-11) treated male and female rats. Evidence of dose and time-dependent response

The effect of a novel phosphorothionate, the methyl ester of 2-butenoic acid-3-diethoxy phosphinothioyl (RPR-II) was studied on membrane bound target enzymes Acid (AcP) and Alkaline (AkP) Phosphatases in different tissues of male and female albino Wistar rats. Three sub-chronic doses 0.014 (low), 0.028 (medium) and 0.042 (high)mg/kg-1 were administered to the rats daily for a period of 90 days. The long term and repeated administration of RPR-II caused significant increase of AcP and AkP in serum and kidney (AcP), whereas these enzymes simultaneously decreased significantly in liver, kidney (female rat AkP) and lung tissues in both male and female rats after 45 and 90 days of treatment. However, the kidney AcP increased significantly in both the sexes which is suggestive of an increase in synthesis of this enzyme which may be an adaptive mechanism to the toxicant stress. The changes in serum, liver, kidney and lung of both male and female rats by this compound were statistically significant when compared with two way Anova showing that they are dose and time dependent. The alterations in male rats were statistically insignificant when compared with female rats showing no sexual dimorphism by this compound. Recovery was observed after 28 days of post treatment (withdrawal study) indicating reversal of the toxic symptoms once the toxicant is removed. High degree negative correlation was observed for serum versus liver and lung and in other cases substantial correlation was observed. The changes observed in these enzymes showed that liver was most susceptible followed by lung and kidney. There are marker enzymes and their increase in different tissues might be due to the increased permeability of plasma membrane or cellular necrosis, showing the stress condition of the treated rats. This investigation elucidates the effect of these biomarker enzymes which increased in blood, might be due to the necrosis of liver, kidney and lung tissues by this compound.     

The effect of sub-acute and sub-chronic exposure of rats to the glyphosate-based herbicide Roundup

Roundup is a glyphosate-based herbicide that includes 78.5% glyphosate and surfactant at lower toxic concentrations. Glyphosate is an organophosphorated non-selective agrochemical widely used in many countries including Turkey and acts after the sprout in a systemic way. The objective of this study was to analyze toxic effects of the herbicide Roundup in rat liver. Animals were treated with 56mg/kg (p.o.) and 560mg/kg (p.o.) of Roundup (78% glyphosate+surfactant) each day, during 5 and 13 weeks. Hepatotoxicity was monitored by quantitative analysis of the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activities and measured amount of serum lipoprotein (LDL, HDL), total cholesterol and creatinine were used as the biochemical markers of liver damages. Besides the biochemical analysis, we also investigated liver tissues histopathologically. Sub-chronic treatment, starting from the low and high doses of Roundup, it was observed that there were mild effects on activity of ALT, AST and LDH enzymes indicating the hepatic toxicity induced by Roundup. It was found that the mild effects were different on the enzymes in male and female rats of treatment groups. Also it was found some difference in serum lipoprotein (LDL, HDL) and t-cholesterol. There was no difference creatinine value between control and treatment groups but it was observed that degenerative formation such as mononuclear cell infiltration and congestion of the liver tissues of treatment groups.     

Effect of Kalmegh extract on rat liver and serum enzymes

Oral administration of Kalmegh extract under acute (single dosage) and sub-acute (for 7 and 15 consecutive days) conditions at a dosage of 0.5 g dry leaf/kg/day to adult rats produced no change in the activities of glutamate oxaloacetic transaminase (GOT) and glutamate pyruvic transaminase (GPT) in liver and rerum. Administration of ethyl alcohol at a dosage of 0.2 g/kg/day (oral) for 7 and 15 consecutive days produced an appreciable increase in liver GOT and GPT activities. No appreciable change in serum GOT and GPT activities was observed under similar condition of treatment. Oral administration of a high dosage of ethyl alcohol (3 g/kg/day) produced significant increase in the activities of serum enzymes only. This alcohol-induced increase in serum transaminase activity became normal with pre- and post-treatment of Kalmegh extract (0.5 g/kg/day). This result suggests that Kalmegh extract protects alcohol-induced toxic-effect in liver tissue.     

The effects of moderate drinking and abstinence on serum and urinary beta-hexosaminidase levels

The effects of moderate alcohol intake on serum (SHEX)- and urinary beta-hexosaminidase (UHEX) were studied in ten healthy volunteers, who ingested 60 g of 100% ethanol daily for 10 days. The drinking period was preceded and followed by an abstinence period. Moderate drinking and abstinence were rapidly and significantly reflected on SHEX, while UHEX levels did not change significantly during the study. Gramma-glutamyl transpeptidase (GGT), aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) decreased during the first abstinence period (P less than 0.05), but stayed thereafter at a constant level. It is concluded that SHEX may better reflect recent alcohol consumption than UHEX, GGT, ASAT or ALAT.     

Effect of methomyl on hepatic mixed function oxidases in rats

Objective:

To study the effect of the methomyl on mixed function oxidase system in rats.

Materials and Methods:

The effect of the methomyl on mixed function oxidase was studied using different dosages, durations and sex. Microsomes were isolated using the calcium precipitation method. The levels of cytochrome P₄₅₀ , and cytochrome b₅ were determined using extinction coefficient of 91 and 85 mM^-1 respectively. The activities of drug metabolizing enzymes, hemoglobin content, liver function enzymes, and serum cholinesterase activity were assayed by using standard methods.

Results:

Intraperitoneal administration of methomyl (4 mg/kg body weight) showed significant decrease in the level of cytochrome P₄₅₀ , and the activities of aminopyrine N-demethylase and aniline hydroxylase on the third day of the treatment. Methomyl (4 mg/kg) treatment of old male rat and adult female rat also showed a decrease in the level of cytochrome P₄₅₀ , and aminopyrine N-demethylase activity. The serum samples from methomyl treated rats (male and female), when analyzed for alanine aminotransferase (SGPT) and aspartate aminotransferase (SGOT) as markers of the liver toxicity, showed significant increase in the activity. The activities of SGPT and SGOT were significantly higher in the treated rats (2 and 4 mg/kg) than in the control group. A significant decrease in the level of hemoglobin and serum cholinesterase activity was observed, when there was an increase in the dose level. A significant increase was observed in alkaline phosphatase activity at all dose levels.

Conclusion:

Methomyl influences mixed function oxidase and creates abnormality of liver functions in the rats. This effect depends on the dose and duration of methomyl.     

ACID AND ALKALINE PHOSPHATASE ACTIVITIES IN A NOVEL PHOSPHOROTHIONATE (RPR-11) TREATED MALE AND FEMALE RATS. EVIDENCE OF DOSE AND TIME-DEPENDENT RESPONSE

The effect of a novel phosphorothionate, the methyl ester of 2-butenoic acid-3-diethoxy phosphinothioyl (RPR-II) was studied on membrane bound target enzymes Acid (AcP) and Alkaline (AkP) Phosphatases in different tissues of male and female albino Wistar rats. Three sub-chronic doses 0.014 (low), 0.028 (medium) and 0.042 (high) mg/kg-1 were administered to the rats daily for a period of 90 days. The long term and repeated administration of RPR-II caused significant increase of AcP and AkP in serum and kidney (AcP), whereas these enzymes simultaneously decreased significantly in liver, kidney (female rat AkP) and lung tissues in both male and female rats after 45 and 90 days of treatment. However, the kidney AcP increased significantly in both the sexes which is suggestive of an increase in synthesis of this enzyme which may be an adaptive mechanism to the toxicant stress. The changes in serum, liver, kidney and lung of both male and female rats by this compound were statistically significant when compared with two way Anova showing that they are dose and time dependent. The alterations in male rats were statistically insignificant when compared with female rats showing no sexual dimorphism by this compound. Recovery was observed after 28 days of post treatment (withdrawal study) indicating reversal of the toxic symptoms once the toxicant is removed. High degree negative correlation was observed for serum versus liver and lung and in other cases substantial correlation was observed. The changes observed in these enzymes showed that liver was most susceptible followed by lung and kidney. There are marker enzymes and their increase in different tissues might be due to the increased permeability of plasma membrane or cellular necrosis, showing the stress condition of the treated rats. This investigation elucidates the effect of these biomarker enzymes which increased in blood, might be due to the necrosis of liver, kidney and lung tissues by this compound.     

Acute effects of 2-nitropropane on rat liver and brain

Intraperitoneal injection (50 mg/kg) of 2-nitropropane (2-NP) induced lipid accumulation, centrilobular necrosis, degranulation of rough endoplasmic reticulum, proliferation of smooth endoplasmic reticulum and mitochondrial abnormalities in rat liver 24 h after exposure. These pathological changes were accompanied by elevated serum alanine aminotransferase (ALAT) levels. Hepatic glutathione content increased rapidly in exposed rats. 2-NP depressed markedly hepatic cytochrome P-450 and microsomal monooxygenase activity while the enzymes, epoxide hydratase, UDP-glucuronosyltransferase and cytosolic glutathione peroxidase were enhanced. 2-NP caused an increase of acetylcholine esterase activity in the brain. This effect was also detected in synaptosomes isolated from exposed rats. The results suggest peroxidative damage in the cells.     

Down-regulation of hepatic cytochrome P450 enzymes associated with cisplatin-induced acute renal failure in male rats

Hepatic drug metabolism is impaired in experimental animals and humans with renal diseases. An anticancer drug, cisplatin induces acute renal failure (ARF) in rats. Under the same experimental conditions, cisplatin causes down-regulation of hepatic cytochrome P450 (P450) enzymes in an isozyme selective manner. The present study examined the pathological role of ARF in the down-regulation of hepatic P450 enzymes in the cisplatin-treated rats. Male rats with single dose of intraperitoneally cisplatin (5 mg/kg) caused marked changes in renal parameters, BUN and serum creatinine but not hepatic parameters, serum alanine aminotransferase or aspartate aminotransferase. The rats also suffered from down-regulation of hepatic microsomal CYP2C11 and CYP3A2, male specific P450 isozymes, but not CYP1A2, CYP2E1, or CYP2D2. The decrease in serum testosterone level was also observed in injured rats, which was consistent with the selective effects on male specific P450 enzymes. Protection of rats against cisplatin-induced ARF by dimethylthiourea, a hydroxyl radical scavenger, also protected rats against the decrease in serum testosterone levels and the down-regulation of CYP2C11 and CYP3A2. Carboplatin, an analogue to cisplatin but no ARF inducer, did not cause decrease in serum testosterone levels and down-regulation of hepatic male specific P450 enzymes. These results suggest that down-regulation of hepatic P450 enzymes in male rats given cisplatin is closely related to the cisplatin-induced ARF and the resultant impairment of testis function.     

Erythrocyte and Plasma Cholinesterase Activity in Male and Female Rhesus Monkeys before and after Exposure to Sarin

The rhesus monkey (Macaca mulatta) has a menstrual cycle similarto the human. Differences in hormone levels have been demonstratedbetween the sexes and in females during the menstrual cyclebut these differences in terms of organophosphorus toxicityhave not been explored. Plasma cholinesterase (ChE/BuChE) anderythrocyte (RBC) acetylcholinesterase (AChE) activity weremeasured before and after exposure to the organophosphorus compoundsarin (11 µg/kg, iv; 0.75 LD50) in six male and six femalerhesus monkeys. After baseline measurements were obtained, sarinwas administered to atropinized monkeys to determine in vivodifferences between the sexes in their response to sarin. Withthe baseline values, the intraanimal and intragroup BuChE/AChEvariations were found to be minimal. Following sarin intoxicationand 2-PAM treatment no significant differences were seen betweenthe sexes in the rate of reactivation of BuChE or AChE by 2-PAM.The rate of aging of sarin phosphonylated RBC AChE between thesexes was also similar. De novo regeneration of RBC AChE andplasma BuChE after sarin intoxication was different betweenthe male and female monkeys. The female plasma BuChE recoveryrate was 48% slower than the male recovery rate, while the early(first 63 days) RBC AChE recovery rate was 24.5% faster in thefemales. In conclusion, there probably are not any clinicallysignificant differences between male and female rhesus monkeysacutely intoxicated with sarin. However, on subsequent exposureclinical differences may be observed due to substantial differencesin the rate of de novo synthesis of both plasma BuChE and RBCAChE.