Influence of non-steroid anti-inflammatory and immunosuppressive drugs on hepatic tryptophan pyrrolase activity in rats

High oral doses of the anti-inflammatory drugs indomethacin, acetylsalicyclic acid, sodium salicylate, salicylamide, mefenamic acid, flufenamic acid, amidopyrine, phenylbutazone and benzydamine administered repeatedly, did not influence tryptophan pyrrolase activity in livers of intact rats. The nonresponsiveness of tryptophan pyrrolase was in contrast to a stimulation of tyrosine aminotransferase caused by flufenamic acid.Induction of tryptophan pyrrolase due to hydrocortisone was not inhibited generally by non-steroid drugs; exceptions were flufenamic acid and benzydamine which depressed hormonal induction. The authors' recent statement is confirmed that inhibition of protein synthesis due to induction is no essential property of non-steroid antiinflammatory drugs.The immunosuppressive drugs cyclophosphamide, triaziquone and azathioprine increased tryptophan pyrrolase activity, probably due to an inhibition of enzyme degradation; chloroquine, 6-mercaptopurin, 6-azauridin and amethopterin did not influence enzyme activity. Induction of tryptophan pyrrolase due to hydrocortisone was depressed by azathioprine, 6-mercaptopurin, 6-azauridin and amethopterin.     

Enzymatic sulfation of steroids--XX. Effects of ten drugs on the hepatic glucocorticoid sulfotransferase activity of rats in vitro and in vivo

The effects of ten drugs on hepatic glucocorticoid sulfotransferase activity (HGSTA) were examined in male rats. The enzyme activity per 100 g body weight was elevated 152, 94.9, 140, 140, 73.1, 63.9, 76.9, and 140% after administration of daily i.p. doses of 111 mg spironolactone/kg (6-10 days), 66.7 mg WIN-24540/kg (6-10 days), 150 mg metyrapone/kg (19-31 days), 33.3 mg pentachlorophenol/kg (9-16 days), 16.5 mg aspirin/kg (10-16 days), 90.5 mg alloxan/kg (23.27 days), 104 mg aminoglutethimide/kg (12-20 days), and 16.8 mg propranolol/kg (21-27 days). Shorter experimental periods or lower drug doses caused smaller effects on HGSTA. Most notably, spironolactone (111 mg/kg) and WIN-24540 (66.7 mg/kg) caused 50-75% elevation of HGSTA in 2 days. Effects of WIN-24540, aspirin and pentachlorophenol were due mostly to elevation of hepatic levels of sulfotransferase III (STIII), the glucocorticoid-preferring sulfotransferase of rat liver. Effects of the other test drugs were due to elevation of hepatic levels of sulfotransferases I and II (STI and STII), which much prefer dehydroepiandrosterone as substrate, but also catalyze glucocorticoid sulfation. Enzyme inhibition studies showed that the test drugs interacted with the HGSTA in vitro in a fashion that appeared to be related to the in vivo effects already described. None of the drugs interacted exclusively with STI, STII or STIII in vitro. However, some differences of the strengths of individual drug-sulfotransferase interactions were observed. The drug effects are discussed in relation to drug and glucocorticoid actions.     

Effects of soyasaponins on liver tyrosine aminotransferase activity induced by cortisone in adrenalectomized rats.

It is well known that liver tyrosine aminotransferase activity is induced by administration of steroids to adrenalectomized rats. When total soyasaponins were injected intraperitoneally into adrenalectomized rats, liver tyrosine aminotransferase activity was not found to be induced. Administration of a low dose of cortisone (2.5 mg/kg body weight) to adrenalectomized rats also failed to induce liver tyrosine aminotransferase. On the other hand, this enzyme was found to be induced by administration of this low dose of cortisone with total soyasaponins (100 mg/kg body weight).     

Effects of various soyasaponins on liver tyrosine aminotransferase activity induced by cortisone in adrenalectomized rats.

It is well known that liver tyrosine aminotransferase activity is induced by administration of steroids to adrenalectomized rats. When various soyasaponins (e.g. soyasaponins I, II, III, A (1) and A (2)) were injected intraperitoneally into adrenalectomized rats, liver tyrosine aminotransferase activity was not found to be induced. Administration of a low dose of cortisone (2.5 mg/kg body weight) to adrenalectomized rats also failed to induce liver tyrosine aminotransferase. However, this enzyme was found to be induced by administration of this low dose of cortisone with soyasaponins II (2.5 mg/kg and 5.0 mg/kg) and A (2) (5.0 mg/kg).     

Influence of methamphetamine and neuroleptic drugs on tyrosine hydroxylase activity

After rats had been treated with drugs for 36 hr, striatal and adrenal tyrosine hydroxylase (TH) activities were determined by the coupled decarboxylase method. Treatment with methamphetamine 10 mg/kg, s.c., depressed striatal TH activity but elevated adrenal enzyme activity. Neither chlopromazine nor haloperidol affected TH activity in the striatum; however, when either of these neuroleptic drugs was administered concurrently with methamphetamine, the depression of striatal enzyme activity produced by methamphetamine was prevented. Adrenal enzyme activity was increased by chlorpromazine 15 mg/kg, i.p.; when this dose was administered concurrently with methamphetamine, the enzyme activity was greater than that produced by either drug alone. In contrast to chlorpromazine, haloperidol 5 mg/kg, i.p., had no effect on adrenal TH activity and seemed to impair the elevation produced by methamphetamine.     

Correlation of intrinsic in vitro and in vivo clearance for drugs metabolized by hepatic UDP-glucuronosyltransferases in rats

A method for quantitatively predicting the hepatic clearance of drugs by UDP-glucuronosyltransferases (UGTs) from in vitro data has not yet been established. We examined the relationship between in vitro and in vivo intrinsic clearance by rat hepatic UGTs using 10 drugs. For these 10 drugs, the in vitro intrinsic clearance by UGTs (CL(int, in vitro)) measured using alamethicin-activated rat liver microsomes was in the range 0.10-4500 ml/min/kg. Microsomal binding (f(u, mic)) was determined to be in the range 0.29-0.95 and the unbound intrinsic clearance (CL(uint, in vitro)) to be in the range 0.11-9600 ml/min/kg. The contribution of rat hepatic glucuronidation to drug elimination was 12.0%-76.6% and in vivo intrinsic clearance by UGTs was 5.7-9000 ml/min/kg. To evaluate the discrepancy between the in vitro and in vivo values, a scaling factor was calculated (CL(int, in vivo)/CL(int, in vitro)); the values were found to be in the range 0.89-110. The average fold error of the scaling factor values incorporating f(u, mic) was closer to unity than that without f(u, mic). The scaling factor values incorporating f(u, mic) were <10 in 8/10 drugs and <2 in 6/10 drugs, indicating a small discrepancy between in vitro and in vivo values. Thus, using alamethicin-activated liver microsomes, incorporating f(u, mic) into CL(int, in vitro), and considering the contribution of glucuronidation may enable us to quantitatively predict in vivo hepatic glucuronidation from in vitro data.     

Lithium regulates protein tyrosine phosphatase activity in vitro and in vivo

RATIONALE: Lithium has been shown to regulate multiple intracellular signaling pathways by affecting various protein kinases. However, the counterpart of protein kinases, i.e., protein phosphatases may play an important role in lithium-regulated cellular signaling and functions. OBJECTIVES: The present work was designed to test the effect of lithium on protein phosphatases in vitro and in vivo. METHODS: PC12 cells were used as an in vitro model to characterize the effect of lithium on protein phosphatase activity. Rats treated with a lithium-containing diet were used to examine the in vivo effect of the drug on brain protein phosphatase activity.RESULTS. Lithium stimulated protein tyrosine phosphatase (PTPase) activity in a dose- and time-dependent manner in PC12 cells. A maximal stimulation of 87% was observed after 6 h of incubation with 3 mM LiCl. In contrast, protein serine phosphatase (PSPase) activity was not changed by lithium. The stimulatory effect on PTPase was not due to a direct action of the ion on the enzymes, but its selectivity was noted since treatment of cells with other monovalent cations exhibited no effect on PTPase activity. Lithium appeared to target specific PTPase(s) as it stimulated membrane-associated PTPase activity without affecting cytosolic or nuclear enzymatic activities. Moreover, the stimulation of PTPase activity in PC12 cells by lithium is independent of de novo protein synthesis. In the rat, 3 weeks of lithium treatment significantly elevated PTPase activity in hippocampus, striatum and cortex. CONCLUSION: The present findings provide the first evidence that lithium treatment selectively increases membrane-associated PTPase activity and suggest that this action may contribute to the pharmacotherapeutic actions of lithium.     

Antimutagenic and anticlastogenic effects of Turkish Black Tea on TA98 and TA100 strains of Salmonella typhimurium (in vitro) and mice (in vivo)

Context: Black tea has been reported to have significant antimutagenic and anticarcinogenic properties associated with its polyphenols theaflavins (TF) and thearubigins (TR). Similarly, Turkish black tea (TBT) also contains a considerable amount of TF and TR.

Objective: This study investigated the mutagenic, antimutagenic and anticlastogenic properties of TBT.

Materials and methods: The mutagenic and antimutagenic effects of TBT (10 to 40000?μg/plate) were investigated in vitro on Salmonella strains TA98 and TA100 with and without S9 fraction. Anticlastogenic effect was studied at concentrations of 300–1200?mg/kg TBT extract by chromosomal aberrations (CA) assay from bone marrow of mice.

Results: The results of this study did not reveal any mutagenic properties of TBT. On the contrary, TBT extract exhibited antimutagenic activity at >1000?μg/plate concentrations in TA98 strain with and without S9 activation (40% inhibition with S9 and 27% without S9). In TA100 strain, the antimutagenic activity was observed at?>20,000?μg/plate TBT extracts without S9 activation (28% inhibition) and at >1000?μg/plate with S9 activation (59% inhibition). A significant decrease in the percentage of aberrant cells (12.33%?±?1.27) was observed in dimethylbenz(a)anthracene (DMBA) plus highest concentration (1200?mg/kg) of TBT extract-treated group when compared to only DMBA-treated group (17.00%?±?2.28).

Discussion and conclusion: Results indicated that TBT can be considered as genotoxically safe, because it did not exert any mutagenic and clastogenic effects. As a result, TBT exhibited antimutagenic effects more apparently after metabolic activation in bacterial test system and had an anticlastogenic effect in mice.     

Screening for in vivo (anti)estrogenic activity of ephedrine and p-synephrine and their natural sources Ephedra sinica Stapf. (Ephedraceae) and Citrus aurantium L. (Rutaceae) in rats

Formulations containing Ephedra sinica Stapf. (Ephedraceae) and Citrus aurantium L. (Rutaceae) are consumed worldwide for body weight control. Considering the related adverse effects and the risk potential, the aim of this study is to evaluate the effects of the thermogenic compounds ephedrine, p-sinephrine, E. sinica and C. aurantium in the female reproductive system through the uterotrophic assay in immature female rats. The animals (n = 6–7) received E. sinica 85.5 and 855.0 mg/kg/day, C. aurantium 25.0 and 50.0 mg/kg/day, ephedrine 5.0 mg/kg/day and p-synephrine 50.0 mg/kg/day for three consecutive days by oral gavage. For detection of antiestrogenicity, tamoxifen 20.0 mg/kg/day, E. sinica 855.0 mg/kg/day, C. aurantium 50.0 mg/kg/day, ephedrine 5.0 mg/kg/day and p-synephrine 50.0 mg/kg/day were administered to estrogen-treated females. Macroscopical alterations were evaluated in liver, kidneys, adrenals and uterus. All analyzed substances showed an antiestrogenic potential, but only ephedrine at 0.5 mg/kg/day presented a significative antiestrogenic effect (P < 0.01). Adrenals relative mass were reduced (P < 0.01) in all tested compounds when compared to the control, which seems to be related to the alfa-1-adrenoceptor agonist activity, which promote a vasoconstriction and reduction of the liquid in the organ. The endocrine system is highly complex and there are a number of ways in which a chemical may interfere with it, other in vivo and in vitro assays are being necessary to support this mechanism of action.     

Serum aminotransferase activity as a predictor for estimation of total clearance of hepatically metabolized drugs in rats with acute hepatic failure

The levels of serum aminotransferase activity, including aspartate aminotransferase (AST), in rats with acute hepatic failure at 24 h after an oral administration of CCl4 (0.01-0.5 ml/kg) were about 15-50 times higher (up to nearly 5000 IU/l) than those of vehicle control rats (about 85 IU/l). The values of total clearance (CL(tot)) of cyclosporin A, doxorubicin, tacrolimus and zonisamide in the CCl4-treated rats were decreased to about 1/2-1/3 of those in control rats. There were good correlations between AST activity and hepatic intrinsic clearance (CL(int)) (r=0.733-0.949) for the above drugs, as well as for chlorzoxazone, caffeine, lidocaine and tolbutamide after the intravenous administration of each drug in rats with acute hepatic failure. However, the slope of the linear regression equation, i.e., the ratio of decrease of CL(int) against increase of AST activity, differed markedly among these drugs. We found that there is a good correlation (r=0.953) between the values of the slope and the CL(int) of normal rats for these drugs, except for caffeine. In summary, the linear regression equation enables us to predict the decrease of CL(tot) in rats with acute hepatic failure to be predicted from the increase in serum AST activity. This approach may be useful as a guide for the dose modification of drugs for patients with acute hepatic failure.     

Influence of antidepressant drugs on macrophage cytotoxic activity in rats

The aim of the study was to evaluate the in vivo and in vitro effects of antidepressant drugs on cytotoxic activity of rat spleen macrophages. In the in vivo experiment, rats were injected subcutaneously with two different doses (2 or 10 mg/kg) of desipramine, fluvoxamine and fluoxetine. The drugs were given once, for 2, 4 or 8 weeks. In the in vitro experiment, spleen macrophages were cultured with three different concentrations of desipramine (3.75, 0.75, or 0.075 mM), fluvoxamine (3.14, 0.62, or 0.062 mM), and fluoxetine (3.23, 0.64, or 0.064 mM) for 72 h. The cytotoxic activity of macrophages was evaluated by measuring the lysis of ((51)Cr) chromate-labelled P-815 target cells. In the in vivo experiment, a single dose of fluvoxamine (2 and 10 mg/kg) and fluoxetine (10 mg/kg) significantly decreased macrophage cytotoxic activity. Fluvoxamine (2 and 10 mg/kg), fluoxetine (10 mg/kg) and desipramine (10 mg/kg) administrated for 14 days also decreased macrophage cytotoxic activity. Twenty-eight day treatment with desipramine (2 and 10 mg/kg) decreased macrophage cytotoxic activity. Desipramine, fluvoxamine and fluoxetine given for 56 days did not affect macrophage cytotoxic activity. In the in vitro experiment, antidepressant drugs did not affect the cytotoxic activity of macrophages. The results of the study indicate that the effects of antidepressant drugs on macrophage cytotoxic activity depend on the drug type, dose and duration of the treatment.     

In vivo and in vitro effects of bromelain on PGE(2) and SP concentrations in the inflammatory exudate in rats

The effects of bromelain were examined in rats with subcutaneous carrageenin-induced inflammation. After oral in vivo administration, bromelain (10 and 20 mg/kg p.o.) induced a significant decrease of both PGE(2) and substance P concentrations in the exudate. When added to the inflammatory exudate in vitro, the drug (25, 50, 100 microg/ml) did not affect PGE(2) concentrations and induced an increase in the substance P levels. Our data indicate that bromelain reduces the production of two key mediators of inflammation. This effect does not seem to be related to a direct action of the drug on PGE(2) and SP released in the exudate in response to the inflammatory stimulus.     

Screening for in vivo (anti)estrogenic and (anti)androgenic activities of technical and formulated deltamethrin

Concern over the possibility of hormonal systems being disrupted by chemicals in the environment has led to the development of assays to detect such chemicals. Technical and formulated deltamethrin, a widely used synthetic pyrethroid pesticide, was screened for (anti)estrogenic and (anti)androgenic activities by means of two major in vivo short-term screening tests: the uterotrophic and Hershberger assays. The results reported here indicate the absence of in vivo (anti)estrogenic and (anti)androgenic activities for both technical and formulated deltamethrin at the dose levels tested (2.0 and 4.0 mg/kg/day). However, further tests, including in vitro screening assays, are required to characterize fully the lack of endocrine action of these chemicals.     

Suppression by delta 9-tetrahydrocannabinol of induction of hepatic tyrosine aminotransferase and tryptophan oxygenase.

The present study characterizes the action of Δ⁹-THC on enzyme induction by studying its effects on the induction of hepatic tyrosine aminotransferase (TAT) by steroids. In none of our studies did Δ⁹-THC inhibit TAT activity in the absence of steroid. Although treatment with hydrocortisone (HC, 150 mg/kg, 2 hr prior to sacrifice) caused a 2.1-fold induction of enzyme activity, pretreatment with Δ⁹-THC (200 mg/kg, 2 hr prior to sacrifice) decreased this induction to 1.3-fold. When mice were treated with Δ⁹-THC 1 hr prior to HC induction, TAT activity was induced only 1.1-fold over control while HC alone induced TAT activity 2.5-fold. Even when steroid treatment preceded Δ⁹-THC administration by 3 hr, there was significant inhibitory activity. Enzyme activity at 0, 3, and 6 hr after steroid was 18.7, 41.4, and 55.5 μmol of PPA/g of liver/hr, respectively. When Δ⁹-THC was administered at 3 hr after steroid and mice killed 3 hr later, enzyme activity was reduced to 36.2 μmol PPA/g liver/hr. Inhibition of steroid induction was dose-related over a range of 50–400 mg/kg of Δ⁹-THC. Δ⁹-THC had little effect on induction of TAT or tryptophan oxygenase in mouse liver by tryptophan and had no effect on tryptophan induction of tryptophan oxygenase in rat liver.     

药物的人体内肝脏代谢清除率的体外预测

在药物开发初期,就将药动学性质不佳的新化学实体剔除出去具有十分重要的意义。通过人体内肝脏代谢清除率的体外预测,可以淘汰那些可能从体内迅速被清除的化合物,并可以建立口服生物利用度的预测模型,以指导临床剂量的确定。本文以肝微粒体和肝细胞为模型,阐述药物的人体内肝脏代谢清除率的体外预测过程,并讨论药物的蛋白结合对预测的影响。     

Binding of non-steroid anti-inflammatory drugs and warfarin to liver tissue of rabbits in vitro

Liver slices (10mm 0.1mm thickness) were incubated at 37 degrees C in drug solutions up to 360 min. The drugs were dissolved in Ringer solution of pH 7.0. After 60, 180, 240 and 360 min each drug concentration was determined in the incubation fluid. For all drugs tested equilibrium was obtained after 240 min. The amount of drug taken up by the slices was calculated from the difference to initial concentration. In parallel, samples of the slices were homogenized together with their incubation fluids after the same incubation intervals. The free concentration was determined by ultrafiltration. For warfarin and several non-steroid anti-inflammatory drugs (NSAID), i.e. acetylsalicylic acid, ibuprofen, ketoprofen and oxyphenbutazone, there was no difference between the free drug concentrations in the homogenized and in non-homogenized samples. This suggests that the binding of these drugs to liver tissue was not altered by homogenization. Further was studied whether NSAIDS interfere with binding of warfarin to liver tissue. Acetylsalicylic acid, flurbiprofen, ibuprofen, ketoprofen, oxyphenbutazone and proquazon markedly increased the free concentration of warfarin both in liver slices and homogenates (p less than 0.01). The extent of displacement did not differ between slices and homogenates.     

Inhibition of hepatic mixed-function oxidase activity in vitro and in vivo by various thiono-sulfur-containing compounds.

Ten thiono-sulfur-containing compounds of varying structure were administered by intraperitoneal injection to untreated, phenobarbital-pretreated and 3-methylcholanthrene-pretreated adult male rats. Six hr later, the concentration of hepatic cytochrome P-450 and the ability of the hepatic microsomes to metabolize benzphetamine were examined. In the untreated, phenobarbital-pretreated and 3-methylcholanthrene-pretreated groups, two, four and four compounds, respectively, significantly decreased the concentration of cytochrome P-450 in the hepatic microsomes. A similar effect on benzphetamine metabolism was also seen. When examined 48 hr after the administration of the ten thiono-sulfurcontaining compounds, four, five and seven of the compounds decreased both the levels of hepatic cytochrome P-450 and the rate of benzphetamine metabolism in the untreated, phenobarbital-pretreated and 3-methylcholanthrene-pretreated animals respectively. Eight of the thiono-sulfur-containing compounds were incubated in the presence of NADPH with hepatic microsomes isolated from untreated, phenobarbital-pretreated or 3-methylcholanthrene-pretreated animals. All of the compounds examined significantly decreased the concentration of cytochrome P-450 in the microsomes from each treatment group. Similar reductions in benzphetamine metabolism were also seen. When these same compounds were incubated with microsomes in the absence of NADPH, no significant reduction of cytochrome P-450 or benzphetamine metabolism was seen. When the oxygen analogs of six of the thiono-sulfur compounds were administered in vivo or incubated with hepatic microsomes either in the presence or absence of NADPH, no significant reduction of cytochrome P-450 or benzphetamine metabolism was seen.