Influence of primaquine and ritonavir interaction on CYP3A4 mRNA expression in HepG2 cell culture.

Background: Concomitant treatment with antimalaria and antiretroviral drug is a new challenge in the management of malaria and HIV co-infection. Primaquine is a substrate and also an inhibitor of CYP3A4, while ritonavir is a substrate, an inhibitor, and also an inducer for CYP3A4. The objective of this study is to measure the CYP3A4 mRNA expression in HepG2 cell culture induced by primaquine and ritonavir co-treatment. Methods: For the initial study HepG2 cells were treated with 30, 40, 50 uM of primaquine; 2, 10, 20 uM ritonavir; DMSO ≤0.1 % for negative control; or 20 uM rifampicin for positive control. While for the co-treatment study the cells were treated with 40 uM primaquine+10 uM ritonavir; DMSO ≤0.1 %; or 20 uM rifampicin for 72 hours. The cells were harvested using trypsin–EDTA and total RNA was extracted using the Tripure isolation reagent. After determining the quantity of RNA spectrophotometrically, CYP3A4 mRNA expression was quantified using real-time reverse transcription polymerase chain reaction (RT-PCR). Results: The expression of CYP3A4 mRNA was up-regulated (1.22 fold over control) in HepG2 cells co-treated with primaquine and ritonavir. These data suggest that the induction effect of ritonavir was more dominant than the inhibitory effect of primaquine. Conclusion: Concomitant administration of primaquine and ritonavir result in up-regulation of CYP3A4 mRNA expression in vitro.

Expression of manganese superoxide dismutase in rat blood, heart and brain during induced systemic hypoxia.

Background: Hypoxia results in an increased generation of ROS. Until now, little is known about the role of MnSOD - a major endogenous antioxidant enzyme - on the cell adaptation response against hypoxia. The aim of this study was to determine the MnSOD mRNA expression and levels of specific activity in blood, heart and brain of rats during induced systemic hypoxia. Methods: Twenty-five male Sprague Dawley rats were subjected to systemic hypoxia in an hypoxic chamber (at 8-10% O2) for 0, 1, 7, 14 and 21 days, respectively. The mRNA relative expression of MnSOD was analyzed using Real Time RT-PCR. MnSOD specific activity was determined using xanthine oxidase inhibition assay. Results: The MnSOD mRNA relative expression in rat blood and heart was decreased during early induced systemic hypoxia (day 1) and increased as hypoxia continued, whereas the mRNA expression in brain was increased since day 1 and reached its maximum level at day 7. The result of MnSOD specific activity during early systemic hypoxia was similar to the mRNA expression. Under very late hypoxic condition (day 21), MnSOD specific activity in blood, heart and brain was significantly decreased. We demonstrate a positive correlation between MnSOD mRNA expression and specific activity in these 3 tissues during day 0-14 of induced systemic hypoxia. Furthermore, mRNA expression and specific activity levels in heart strongly correlate with those in blood. Conclusion: The MnSOD expression at early and late phases of induced systemic hypoxia is distinctly regulated. The MnSOD expression in brain differs from that in blood and heart revealing that brain tissue can possibly survive better from induced systemic hypoxia than heart and blood. The determination of MnSOD expression in blood can be used to describe its expression in heart under systemic hypoxic condition.

The effect of lycopene on the total cytochrome P450, CYP1A2 and CYP2E1.

Aim Some carotenoids such as canthaxantin, astaxanthin and beta apo-8’-carotenal were reported to have modulatory effect on the cytochrome P450. The present study was conducted to investigate the effects of lycopene, a nonprovitamin A carotenoid, on microsomal cytochrome P450, CYP1A2 and CYP2E1. Methods Total cytochrome P450 levels, CYP1A2 and CYP2E1-catalyzed reactions (acetanilide 4-hydroxylation and p-nitrophenol hydroxylation) were studied in the liver microsomes of male Sprague Dawley rats. Microsomes were prepared using differential centrifugation combined with calcium aggregation method. Lycopene was orally administered in the dosages of 0, 25, 50 or 100 mg/kgBW/day for 14 days in a repeated fashion. Data were analyzed using ANOVA test. Results Total cytochrome P450 level and acetanilide 4-hydroxylase activity were unaffected by any of the treatments. The CYP2E1 probe enzyme (p-nitrophenol hydroxylase) was signifi cantly reduced by repeated administration of 100 mg/kgBW/day lycopene (7.88 + 2.04 vs 12.26 + 2.77 n mol/min/mg prot). Conclusion The present results suggest that lycopene does not affect the total cytochrome P450 or CYP1A2 activity but it inhibits the activity of CYP2E1 (p-nitrophenol hydroxylase) in the rat.

Expression of hypoxia inducible factor-1a (HIF-1a) gene and apoptosis in the heart induced by systemic hypoxia.

Aim This study explored the expression of HIF-1α in hypoxic cardiac muscle in mice, and observed the evidence of apoptosis in hypoxia induced cardiomyocyte. Methods Male Sprague-Dawley rats, were randomized into 7 groups (n= 4 per group): control normoxia group that was exposed to atmospheric oxygen and hypoxia groups that were housed in hypoxic chambers (O2 level 8%) for 1, 3, 7, 14, 21, and 28 days respectively. Animals were sacrificed, hearts were rapidly excised, total RNA was extracted with an mRNA isolation kit and the expression of HIF-1α mRNA was then detected by real-time RT-PCR. Apoptosis was assessed by TUNEL method. Results For rat in hypoxia group, the expression of HIF-1α mRNA in cardiac myocytes was clearly up-regulated compared to the control normoxia group. Further, HIF-1α expression level elevated gradually and reached a peak at 21 days of hypoxia. No cell labeled by the TUNEL method was detected in the control group. Compared with the control group, the apoptotic index was significantly increased in the hypoxia group (P < 0.05). There was no significant correlation between the elevation of HIF-1α mRNA and the elevation of apoptotic index. Conclusion Systemic chronic hypoxia caused the elevation of HIF-1α mRNA and apoptosis in cardiac myocytes.