Genetically modified cell lines can be very useful models for assessing the toxicologic effects of modulation of expression of individual gene products in comparison to their isogenic parental control cell lines. This symposium begins with an overview of general issues related to development and utilization of model systems created by transfection of cell lines to induce elevated expression of ...

Notoginsenoside R1 (R1) is the main bioactive component in Panax notoginseng, an old herb medicine widely used in Asian countries in the treatment of microcirculatory diseases. However, little is known about the effect of R1 on inflammatory bowel disease (IBD). The present study demonstrated that R1 alleviated the severity of dextran sulfate sodium–induced colitis in mice by decreasing the acti...

The adverse effects to humans and environment of only few chemicals are well known. Absorption, distribution, metabolism, and excretion (ADME) are the steps of pharmaco/toxicokinetics that determine the internal dose of chemicals to which the organism is exposed. Of all the xenobiotic-metabolizing enzymes, the cytochrome P450 (CYP) enzymes are the most important due to their abundance and versa...

The aryl hydrocarbon receptor (Ahr) is a highly conserved nuclear receptor that plays an important role in the manifestation of toxicity induced by polycyclic aromatic hydrocarbons. As a xenobiotic sensor, Ahr is involved in chemical biotransformation through activation of drug metabolizing enzymes. The activated Ahr cooperates with coactivator complexes to induce epigenetic modifications at ta...

In recent years, the consumption and use of dietary supplements containing concentrated phytochemicals (e.g. flavonoids) increased dramatically. Flavonoids, as foreign compounds (xenobiotics), have great potential to modulate the activity of cytochrome P450s (CYPs), xenobiotic-metabolizing enzymes involved in the activation and detoxification of food and environmental carcinogens. Thus, the aim...

An important requirement for physiologic homeostasis is the detoxification and removal of endogenous hormones and xenobiotic compounds with biological activity. Much of the detoxification is performed by cytochrome P-450 enzymes, many of which have broad substrate specificity and are inducible by hundreds of different compounds, including steroids. The ingestion of dietary steroids and lipids i...

The kidney is the target of numerous xenobiotic toxicants, including environmental chemicals. Anatomical, physiological, and biochemical features of the kidney make it particularly sensitive to many environmental compounds. Factors contributing to the sensitivity of the kidney include: large blood flow, the presence of a variety of xenobiotic transporters and metabolizing enzymes, and concentra...

Xenobiotic metabolism has been proposed to play a role in modulating the rate of aging. Xenobiotic metabolizing enzymes (XME) are expressed at higher levels in calorically restricted mice (CR) and in GH/IGF-I-deficient, long-lived mutant mice. In this study, we show that many phase I XME genes are similarly upregulated in additional long-lived mouse models, including "crowded litter" (CL) mice,...

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates a plethora of target genes. Historically, the AhR has been studied as a regulator of xenobiotic metabolizing enzyme genes, notably cytochrome P4501A1 encoded by CYP1A1, in response to the exogenous prototypical ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). AhR activity depends on its binding to th...

Notoginsenoside R1 (R1) is the main bioactive component in Panax notoginseng, an old herb medicine widely used in Asian countries in the treatment of microcirculatory diseases. However, little is known about the effect of R1 on inflammatory bowel disease (IBD). The present study demonstrated that R1 alleviated the severity of dextran sulfate sodium-induced colitis in mice by decreasing the acti...