Comparative evaluation of phenobarbital-induced CYP3A and CYP2H1 gene expression by quantitative RT-PCR in Bantam, Bantamized White Leghorn and White Leghorn chicks

The present work was to study induction of cytochrome P450 (CYP)3A and CYP2H1 gene by reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative RTPCR in Bantam, Bantamized White Leghorn and White Leghorn chicks. Out of 18 chicks total 3 from each group (Bantam, Bantamized White Leghorn and White Leghorn) were treated intraperitoneal with phenobarbital at the dose rate of 12 mg/100 g (body weight) while the control group was treated with the saline. Total RNA was extracted from the liver samples using Tri Reagent based method. First strand cDNA was synthesized using one step RT-PCR kit. The PCR was performed and the product was subjected to agarose gel electrophoresis. Quantitative RT-PCR was conducted to quantify gene expression level of CYP3A and CYP2H1 genes. Relative expression ratio of CYP3A and CYP2H1 genes was calculated using relative expression software tool (REST). It was found that CYP3A is up regulated by factor of 1.34, 14.51 and 1.00 in Bantam, Bantamized White Leghorn and White Leghorn chicks, respectively. In Bantam and Bantamized White Leghorn chicks CYP2H1 gene was up regulated by factor 1.50 and 80.87, respectively but down regulated by a factor of 1.97 in White Leghorn chicks. The PCR efficiency ranged from 1.30 to 1.70, 0.86 to 1.70 and 0.91 to 1.58 for CYP3A, CYP2H1 and beta-actin, respectively in Bantam, Bantamized White Leghorn and White Leghorn chicks.

Effect of beta-myrcene on pentobarbital sleeping time

Evidence that beta-myrcene (MYR) interferes with the metabolic activation of premutagens has been provided by in vitro studies. In order to determine whether MYR also interferes with the in vivo metabolism of xenobiotics, thereby modifying pharmacological responses to drugs, we investigated the effects of this monoterpene on pentobarbital (PT) sleeping time in rats. Two experiments were carried out. In the first, a single dose of MYR (0.25, 0.5 or 1.0 g/kg po) was given 1 h before PT (40 mg/kg ip). No effect was observed with the two lowest doses, but the highest MYR dose given 1 h before PT increased the PT-induced sleeping time (131 +/- 15 min vs 64 +/- 15 min for controls, mean +/- SD). In the second experiment, male rats were treated with MYR (1.0 g/kg po once a day) for 14 days and injected with PT (40 mg/kg ip) 24 h after the last dose of MYR. Repeated treatment with MYR markedly reduced PT sleeping time compared to the vehicle-treated control group (21 +/- 13 min vs 35 +/- 19 min for controls, mean +/- SD). These results indicate that MYR interferes with the in vivo barbiturate metabolism and support the view that MYR induces the phenobarbital-inducible cytochrome P-450 (P-450 2B subfamily) enzymes in the rat

Studies on the induction of cinnamic acid 4-hydroxylase in potato tuber.

The change in activity of cinnamic acid 4-hydroxylase (CA4H) in potato parenchyma tissue exposed to various conditions has been examined. Maximum induction of CA4H activity was obtained at 18 hr of incubation. Though CA4H induction can occur in dark, over 100% increase in enzyme activity was obtained on exposure of the tissue to light. Actinomycin D and cycloheximide inhibited the induction process. Mn2+, though known to cause an induction of CA4H in Jerusalem Artichoke, strongly inhibited potato CA4H induction. Dithiothreitol enhanced the CA4H activity due to either activation or protection of the enzyme. CA4H induction was significantly regulated at very low concentrations of trans-cinnamate and paracoumarate.

Effect of masheri, a pyrolysed tobacco product on carcinogen metabolizing enzymes.

Studies on the modulation of the carcinogen metabolizing enzymes on treatment with masheri extract (ME) and benzo (a) pyrene (B (a)P), were carried out in male Sprague Dawley rats (12 weeks old) fed a nutritionally adequate standard diet. Injection (ip) of ME and B (a) P at 3/4 LD50 dose given in 3 doses at 24 hr interval increased the phase I activating enzymes, viz. cytochrome P-450, benzo (a) pyrene hydroxylase and benzphetamine demethylase while both ME and B (a) P significantly depleted glutathione content and decreased glutathione-S transferase activity. Furthermore, the same treatment of ME and B (a) P significantly depleted the hepatic vitamin A pool while a concommittant increase in vitamin C content was observed.