Effect of (-)- Δ9 -tetrahydrocannabinoid on the hepatic redox state of mice

(-)-∆9-Tetrahydrocannabinol (∆9-THC), a psychoactive component of marijuana, has been reported to induce oxidative damage in vivo and in vitro. In this study, we administered (∆9-THC to healthy C57BL/6J mice aged 15 weeks in order to determine its effect on hepatic redox state. Mice were divided into 3 groups: (∆9-THC (N = 10), treated with 10 mg/kg body weight (∆9-THC daily; VCtrl (N = 10), treated with vehicle [1:1:18, cremophor EL® (polyoxyl 35 castor oil)/ethanol/saline]; Ctrl (N = 10), treated with saline. Animals were injected ip twice a day with 5 mg/kg body weight for 10 days. Lipid peroxidation, protein carbonylation and DNA oxidation were used as biomarkers of oxidative stress. The endogenous antioxidant defenses analyzed were glutathione (GSH) levels as well as enzyme activities of superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase, and glutathione peroxidase (GPx) in liver homogenates. The levels of mRNA of the cannabinoid receptors CB1 and CB2 were also monitored. Treatment with ∆9-THC did not produce significant changes in oxidative stress markers or in mRNA levels of CB1 and CB2 receptors in the liver of mice, but attenuated the increase in the selenium-dependent GPx activity (∆9-THC: 8 percent; VCtrl: 23 percent increase) and the GSH/oxidized GSH ratio (∆9-THC: 61 percent; VCtrl: 96 percent increase), caused by treatment with the vehicle. ∆9-THC administration did not show any harmful effects on lipid peroxidation, protein carboxylation or DNA oxidation in the healthy liver of mice but attenuated unexpected effects produced by the vehicle containing ethanol/cremophor EL®.

Characterization of rat heart alkaline phosphatase isoenzymes and modulation of activity

Alkaline phosphatase (ALP) is important in calcification and its expression seems to be associated with the inflammatory process. We investigated the in vitro acute effects of compounds used for the prevention or treatment of cardiovascular diseases on total ALP activity from male Wistar rat heart homogenate. ALP activity was determined by quantifying, at 410 nm, the p-nitrophenol released from p-nitrophenylphosphate (substrate in Tris buffer, pH 10.4). Using specific inhibitors of ALP activity and the reverse transcription-polymerase chain reaction, we showed that the rat heart had high ALP activity (31.73 ± 3.43 nmol p-nitrophenol·mg protein-1·min-1): mainly tissue-nonspecific ALP but also tissue-specific intestinal ALP type II. Both ALP isoenzymes presented myocardial localization (striated pattern) by immunofluorescence. ALP was inhibited a) strongly by 0.5 mM levamisole, 2 mM theophylline and 2 mM aspirin (91, 77 and 84 percent, respectively) and b) less strongly by 2 mM L-phenylalanine, 100 mL polyphenol-rich beverages and 0.5 mM progesterone (24, 21 to 29 and 11 percent, respectively). â-estradiol and caffeine (0.5 and 2 mM) had no effect; 0.5 mM simvastatin and 2 mM atenolol activated ALP (32 and 36 percent, respectively). Propranolol (2 mM) tended to activate ALP activity and corticosterone activated (18 percent) and inhibited (13 percent) (0.5 and 2 mM, respectively). We report, for the first time, that the rat heart expresses intestinal ALP type II and has high total ALP activity. ALP activity was inhibited by compounds used in the prevention of cardiovascular pathology. ALP manipulation in vivo may constitute an additional target for intervention in cardiovascular diseases.

In vitro modulation of alkaline phosphatase activity of Saccharomyces cerevisiae grown in low or high phosphate medium

Our objective was to characterize the modulation of the activity of Saccharomyces cerevisiae alkaline phosphatases (ALPs) by classic inhibitors of ALP activity, cholesterol and steroid hormones, in order to identify catalytic similarities between yeast and mammalian ALPs. S. cerevisiae expresses two ALPs, coded for by the PHO8 and PHO13 genes. The product of the PHO8 gene is repressible by Pi in the medium. ALP activity from yeast (grown in low or high phosphate medium) homogenates was determined with p-nitrophenylphosphate as substrate, pH 10.4 (lPiALP or hPiALP, respectively). Activation of hPiALP was observed with 5 mM L-amino acids (L-homoarginine _ 186 percent, L-leucine _ 155 percent and L-phenylalanine - 168 percent) and with 1 mM levamisole (122 percent; percentage values, in comparison to control, of recovered activity). EDTA (5 mM) and vanadate (1 mM) distinctly inhibited hPiALP (2 and 20 percent, respectively). L-homoarginine (5 mM) had a lower activating effect on lPiALP (166 percent) and was the strongest hPiALP activator. Corticosterone (5 mM) inhibited hPiALP to 90 percent, but no effect was observed in low phosphate medium. Cholesterol, ß-estradiol and progesterone also had different effects on lPiALP and hPiALP. A concentration-dependent activation of lPiALP minus hPiALP was evident with all three compounds, most especially with ß-estradiol and cholesterol. These results do not allow us to identify similarities of the behavior of S. cerevisiae ALPs and any of the mammalian ALPs but allow us to raise the hypothesis of differential regulation of S. cerevisiae ALPs by L-homoarginine, ß-estradiol and cholesterol and of using these compounds to discriminate between S. cerevisiae lPiALP and hPiALP.

Chronic carriers of hepatitis B surface antigen in an endemic area for shistosomiasis mansoni in Brazil

Data on the association of schistosomiasis and hepatitis B in field-based studies are scarce. Two areas have been selected for this study: i) Queixadinha, endemic for shistosomiasis, with a population of 693 individuals, and ii) Capäo, a control non-endemic area, with 515 inhabitants. Sera of all individuals in both areas were tested for hepatitis B infection, yearly, from 1994 to 1997. In the first area hepatitis B was found in 32.1 per cent of children up to one year old and reached a peak of 68.7 per cent in the age range of 15 to 19 years. In the control area the prevalence of hepatitis B was under 5 per cent up to 19 years of age and the highest prevalence was observed in adults over 45. HBsAg was detected in 9.4 per cent of the individuals living in the endemic area for shistosomiasis and in 1.4 per cent of the controls (OR=4.98; 95 per centCI=3.7-6.7). The index of chronicity of HBsAg was not statistically different in the studied areas (8.1 per cent x 7.3 per cent; OR=1.09; 95 per cent CI=0.42-3.03) nor was it different for people with and without schistosomiasis in Queixadinha (8.7 per cent x 7.0 per cent). We conclude that the Schistosoma mansoni infection has not altered the course of hepatitis B in the studied area.