Characterization of rat glutathione transferases in olfactory epithelium and mucus

International audience; The olfactory epithelium is continuously exposed to exogenous chemicals, including odorants. During the past decade, the enzymes surrounding the olfactory receptors have been shown to make an important contribution to the process of olfaction. Mammalian xenobiotic metabolizing enzymes, such as cytochrome P450, esterases and glutathione transferases (GSTs), have been shown to participate in odorant clearance from the olfactory receptor environment, consequently contributing to the maintenance of sensitivity toward odorants. GSTs have previously been shown to be involved in numerous physiological processes, including detoxification, steroid hormone biosynthesis, and am…

Isoflavonoid-based bone-sparing treatments exert a low activity on reproductive organs and on hepatic metabolism of estradiol in ovariectomized rats

International audience; The use of soy isoflavones is a potential alternative to hormone replacement therapy in post-menopausal bone-loss prevention. Nevertheless, phytoestrogens can target other organs and may disrupt cell proliferation, or could modify endogenous steroid hormone metabolism. These mechanisms could be linked to an increased risk of developing cancer. We therefore studied the possible side effects of such treatments in an experimental model of menopause. Forty adult female Wistar rats were ovariectomized and fed with a genistein-, daidzein- or equol-supplemented diet at bone-sparing levels (10 mg/kg BW/day) for 3 months. The estrogenic effects were assessed by histological a…

Olfactory xenobiotic metabolizing enzymes have an impact on the stimulating properties of some odorants

International audience

Dietary xenoestrogens differentially impair 3T3-L1 preadipocyte differentiation and persistently affect leptin synthesis

International audience; Recent observations have highlighted adipogenesis alterations under exposure to several xenoestrogens at critical stages, and pointed at their possible involvement in the pathogenesis of obesity. However, it remains unclear whether these effects are mediated by classical estrogen receptor (ER) binding and subsequent transcriptional modulation. The aim of this study was to determine the (anti-)adipogenic impact of apigenin, bisphenol A, genistein and 17β-estradiol at the onset of adipose cell maturation, and to correlate it to their estrogenic potential. In steroid-free conditions, 3T3-L1 preadipocytes were induced to differentiate in the presence of xenoestrogens for…

Low and very low density lipoprotein composition and resistance to copper-induced oxidation are not notably modified in smokers.

To study whether tobacco use was associated with oxidative phenomena affecting lipoproteins, we estimated susceptibility of LDL and VLDL to an in vitro copper-mediated oxidation, and measured serum autoantibody titers against oxidized LDL in 45 middle-age healthy nonsmokers, 35 smokers and 37 ex-smokers of both sexes, taking into account the detailed lipid composition of the lipoproteins. VLDL from female smokers had higher triglyceride, phospholipid, apolipoprotein E and alpha-tocopherol content and showed a higher rate of copper-induced oxidation in comparison with those from nonsmokers (P < or = 0.05) whereas the relative composition of these particles in saturated, mono- or poly-unsatur…

Vitamin A modulates the effects of thyroid hormone on UDP-glucuronosyltransferase expression and activity in rat liver.

We studied the influence of thyroid hormones and vitamin A status on the regulation of UDP-glucuronosyltransferase (UGT) expression and the glucuronidation of thyroid hormones by UGTs. For this, we used an original model of rats fed with different vitamin A diets and implanted subcutaneously by osmotic minipumps delivering vehicle or thyroid hormones, which permitted the control of plasma thyroid hormone concentrations. The activity and expression of family 1 UGTs are correlated and were significantly modified by both thyroid status and amounts of retinol in the diet. Dietary vitamin A did not perturbe the UGT1A expression in thyroidectomized animals. Thyroid hormones and dietary vitamin A …

Are taste preferences related to submandibular endocrine or exocrine secretions? A rodent study

National audience

Activity and expression of drug metabolizing enzymes in olfactory mucosa of rats treated by hepatic inducers

International audience; Several drug-metabolizing enzymes (DME), such as cytochrome P450- dependent monooxygenases (CYP) and transferases have been characterized in the olfactory epithelium. Some of them are preferentially expressed in this tissue, while others are similar to those present in the liver. The role of these enzymes remains unclear. Since the olfactory mucosa is in direct contact with the external environment, these enzymes can contribute to the detoxification of chemical compounds. In addition, these enzymes could be involved in the olfaction process, especially in the biotransformation of odorants. Indeed, the rapid inactivation and clearance of odorants is a prerequisite for…

Induction of cytochrome P450 and/or detoxication enzymes by various extracts or rosemary: description of specific patterns

The ability of rosemary to modulate cytochrome P450 (CYP) and detoxication enzymes in rat liver was evaluated by comparing the effects of dried leaves and leaf extracts with different chemical compositions: essential oil (EO) containing monoterpenes, a dichloromethane extract (DCME) containing phenolic diterpenes and a water-soluble extract (WSE) containing phenolic compounds such as rosmarinic acid and flavonoids. Chemical analyses were done in order to characterize the composition of extracts. Male Wistar rats received the leaves or extracts of rosemary in their diet at 0.5% (w/w) for 2 weeks. The effects of such treatments were evaluated for CYP (1A, 2B, 2E1), glutathione S-transferase (…

Effects of endocrine disruptors on genes associated with 17 beta-estradiol metabolism and excretion

International audience; In order to provide a global analysis of the effects of endocrine disruptors on the hormone cellular bioavailability, we combined 17 beta-estradiol (E2) cellular flow studies with real-time PCR and Western blot expression measurements of genes involved in the hormone metabolism and excretion. Three endocrine disruptors commonly found in food were chosen for this study, which was conducted in the estrogen receptor (ER) negative hepatoblastoma HepG2 cell line: bisphenol A (BPA), genistein (GEN) and resveratrol (RES). We showed that 24h after a single dose treatment with genistein, resveratrol or bisphenol A, the expression of ATP-binding cassette transporters (the mult…

Glutathione conjugation of the rabbit mammary pheromone 2-methylbut-2-enal

International audience; In the process of smell, the olfactory signal is initiated by the binding of odorous molecules to olfactory receptors. In the receptor environment,associated events are supposed to modulate this signal.Thus, the xenobiotic metabolizing enzymes, potentially involved in the clearance of the odorous molecules, could modulate the availability of these molecules for the olfactory receptors, and consequently could participate indirectly in the olfactory signal termination. A mammary pheromone, which is an odorous aldehyde (2-methylbut-2-enal or 2MB2) has been recently characterized in the rabbit by our group. The aim of this work was to elucidate the metabolism of 2MB2 in …

C-terminal amino acids are essential for human heat shock protein 70 dimerization

The human inducible heat shock protein 70 (hHsp70), which is involved in several major pathologies, including neurodegenerative disorders and cancer, is a key molecular chaperone and contributes to the proper protein folding and maintenance of a large number of protein structures. Despite its role in disease, the current structural knowledge of hHsp70 is almost exclusively based on its Escherichia coli homolog, DnaK, even though these two proteins only share ~50 % amino acid identity. For the first time, we describe a complete heterologous production and purification strategy that allowed us to obtain a large amount of soluble, full-length, and non-tagged hHsp70. The protein displayed both …

Rat olfactory bulb and epithelium UDP-glucuronosyltransferase 2A1 (UGT2A1) expression: in situ mRNA localization and quantitative analysis.

UDP-glucuronosyltransferases (UGTs) form a multigenic family of enzymes involved in the biotransformation and elimination of numerous endo- and xenobiotic compounds. Beside the diverse UGT isoforms present in the liver as well as in other tissues, the UGT2A1 isoform, also called olfactory UGT, was initially thought to be expressed in the nasal epithelium only. In this work, we demonstrate the UGT2A1 mRNA expression in the olfactory bulb, using in situ hybridization and quantitative reverse transcription-polymerase chain reaction (RT-PCR) techniques. Within the epithelium, UGT2A1 mRNA is mainly found in the sustentacular cells and to a lesser extent in Bowman's gland cells. Moreover, in situ…

Effects of typical inducers on olfactory xenobiotic-metabolizing enzyme, transporter, and transcription factor expression in rats.

International audience; Several xenobiotic-metabolizing enzymes (XMEs) have been identified in the olfactory mucosa (OM) of mammals. However, the molecular mechanisms underlying the regulation of these enzymes have been little explored. In particular, information on the expression of the transcriptional factors in this tissue is quite limited. The aim of the present study was to examine the impact of five typical inducers, Aroclor 1254, 3-methylcholanthrene, dexamethasone, phenobarbital, and ethoxyquin, on the activities and mRNA expression of several XMEs in the OM and in the liver of rats. We also evaluated the effects of these treatments on the mRNA expression of transcription factors an…

Oral homeostasis disruption by medical plasticizer component bisphenol A in adult male rats.

Objectives/Hypothesis Bisphenol A (BPA) is a synthetic estrogen-like chemical mimetic widely used in the manufacture of polycarbonate plastics and epoxy resins found in numerous consumer products including food packaging, medical devices, and dental sealants. Because it is recovered in fluids and it can reach high levels in saliva, this study aimed to evaluate its safety on oral homeostasis by examining its effects on salivary glands, mouth epithelium, water consumption, and salt preference, each parameter being estrogen sensitive. Study Design Randomized controlled trial involving rats. Methods A dose-response study was conducted in adult Wistar rats randomized into five groups (n = 12). B…

A self-inducible heterologous protein expression system in Escherichia coli

AbstractEscherichia coli is an important experimental, medical and industrial cell factory for recombinant protein production. The inducible lac promoter is one of the most commonly used promoters for heterologous protein expression in E. coli. Isopropyl-β-D-thiogalactoside (IPTG) is currently the most efficient molecular inducer for regulating this promoter’s transcriptional activity. However, limitations have been observed in large-scale and microplate production, including toxicity, cost and culture monitoring. Here, we report the novel SILEX (Self-InducibLe Expression) system, which is a convenient, cost-effective alternative that does not require cell density monitoring or IPTG inducti…

Biotransformation of odorants modifies the olfactory signal

International audience

New insights in vertebrate >

International audience

Bisphenol A from drinking water affects taste preferences and oral homeostasis in male rat

National audience

Inhibition of the mammary pheromone catabolism by a second odorant present in the same mixture

National audience

Odorant Metabolism Analysis by an Automated Ex Vivo Headspace Gas-Chromatography Method

International audience; In the olfactory epithelium (OE), odorant metabolizing enzymes have the dual function of volatile component detoxification and active clearance of odorants from the perireceptor environment to respectively maintain the integrity of the tissues and the sensitivity of the detection. Although emphasized by recent studies, this enzymatic mechanism is poorly documented in mammals. Thus, olfactory metabolism has been characterized mainly in vitro and for a limited number of odorants. The automated ex vivo headspace gas-chromatography method that was developed here was validated to account for odorant olfactory metabolism. This method easily permits the measurement of the f…

UDP-glucuronosyltransferases (UGTs) in neuro-olfactory tissues: expression, regulation, and function.

International audience; This work aims to review uridine diphosphate (UDP)-glucuronosyltransferase (UGT) expression and activities along different neuronal structures involved in the common physiological process of olfaction: olfactory epithelium, olfactory bulb, and olfactory cortex. For the first time, using high-throughput in situ hybridization data generated by the Allen Brain Atlas (ABA), we present quantitative analysis of spatial distribution of UGT genes in the mouse brain. The olfactory area is a central nervous system site with the highest expression of UGTs, including UGT isoforms not previously identified in the brain. Since there is evidence of the transfer of xenobiotics to th…

CHARACTERIZATION OF MICROSOMAL CYTOCHROME P450-DEPENDENT MONOOXYGENASES IN THE RAT OLFACTORY MUCOSA

Nasal administration of a drug ensures therapeutic action by rapid systemic absorption and/or the entry of some molecules into the brain through different routes. Many recent studies have pointed out the presence of xenobiotic-metabolizing enzymes in rat olfactory mucosa (OM). Nevertheless, very little is known about the precise identity of isoforms of cytochrome P450 (P450)-dependent monooxygenases (P450) and their metabolic function in this tissue. Therefore, we evaluated mRNA expression of 19 P450 isoforms by semiquantitative reverse transcriptase-polymerase chain reaction and measured their microsomal activity toward six model substrates. For purposes of comparison, studies were conduct…

Cytochrome P450-dependent metabolism of caffeine in [i]Drosophila melanogaster[/i]

Caffeine (1, 3, 7-trimethylxanthine), an alkaloid produced by plants, has antioxidant and insecticide properties that can affect metabolism and cognition. In vertebrates, the metabolites derived from caffeine have been identified, and their functions have been characterized. However, the metabolites of caffeine in insects remain unknown. Thus, using radiolabelled caffeine, we have identified some of the primary caffeine metabolites produced in the body of Drosophila melanogaster males, including theobromine, paraxanthine and theophylline. In contrast to mammals, theobromine was the predominant metabolite (paraxanthine in humans; theophylline in monkeys; 1, 3, 7-trimethyluric acid in rodents…

Effects of oral Bisphenol A exposure on sweet preference and on submandibular salivary gland structure in male adult rat

La Revue de Gériatrie; Objectifs: Le Bisphénol A (BPA) est un œstrogéno-mimétique qui entre dans la fabrication de plastiques en polycarbonate et de résines époxy destinés entre autres à l'élaboration d'emballages alimentaires, de matériel médical et d'amalgames dentaires. Pouvant atteindre des taux élevés dans la salive, l'objectif de cette étude était de vérifier l'innocuité du BPA au niveau buccal en recherchant les effets sur les préférences gustatives et sur les glandes saliuaires, deux paramètres sensibles aux œstrogènes. Matériels et Méthodes: Une étude effet-dose a été réalisée sur des rats Wistar adultes répartis en 5 groupes (n=12). Le Bisphénol A a été administré pendant 6 semain…

Distribution of nitroreductive activity toward nilutamide in rat.

Abstract Nilutamide is a pneumotoxic and hepatotoxic nitroaromatic (R-NO 2 ) antiandrogen used in the treatment of prostate carcinoma in man. Previously, we established that in the rat lung, the drug is metabolized into the corresponding hydroxylamine (R-NHOH) and amine (R-NH 2 ) derivatives. These results evidenced a cytosolic oxygen-sensitive (type II) nitroreductase activity in lung. In the present studies, we extended the characterization of nilutamide metabolism in liver, brain, kidney, heart, blood, intestine (small, cecum, and large, and their respective luminal contents) of male Sprague–Dawley rats. Subcellular fractions for all tissues (except blood) examined (postmitochondrial, cy…

New insights in vertebrate 'biotransfolfaction'

International audience

Odorant metabolism catalyzed by olfactory mucosal enzymes influences peripheral olfactory responses in rats.

International audience; A large set of xenobiotic-metabolizing enzymes (XMEs), such as the cytochrome P450 monooxygenases (CYPs), esterases and transferases, are highly expressed in mammalian olfactory mucosa (OM). These enzymes are known to catalyze the biotransformation of exogenous compounds to facilitate elimination. However, the functions of these enzymes in the olfactory epithelium are not clearly understood. In addition to protecting against inhaled toxic compounds, these enzymes could also metabolize odorant molecules, and thus modify their stimulating properties or inactivate them. In the present study, we investigated the in vitro biotransformation of odorant molecules in the rat …

When the nose must remain responsive: glutathione conjugation of the mammary pheromone in the newborn rabbit

In insects, xenobiotic-metabolizing enzymes were demonstrated to regulate pheromones inactivation, clearing them from the olfactory periphery and keeping receptors ready for stimulation renewal. Here, we investigate whether similar processes could occur in mammals, focusing on the pheromonal communication between female rabbits and their newborns. Lactating rabbits emit in their milk a volatile aldehyde, 2-methylbut-2-enal, that elicits searching-grasping in neonates; called the mammary pheromone (MP), it is critical for pups which are constrained to find nipples within the 5 min of daily nursing. For newborns, it is thus essential to remain sensitive to this odorant during the whole nursin…

Expression and differential localization of xenobiotic transporters in the rat olfactory neuro-epithelium.

International audience; Transporters, such as multidrug resistance P-glycoproteins (MDR), multidrug resistance-related proteins (MRP) and organic anion transporters (OATs), are involved in xenobiotic metabolism, particularly the cellular uptake or efflux of xenobiotics (and endobiotics) or their metabolites. The olfactory epithelium is exposed to both inhaled xenobiotics and those coming from systemic circulation. This tissue has been described as a pathway for xenobiotics to the brain via olfactory perineural space. Thereby, olfactory transporters and xenobiotic metabolizing enzymes, dedicated to the inactivation and the elimination of xenobiotics, have been involved in the toxicological p…

Endocrine disruptors found in food modulate estradiol cellular metabolism

Major sulfation pathway for resveratrol metabolism in human hepatic derived cells and resveratrol –dependent inducibility of conjugating enzymes. Perspective in nutritional prevention

Drosophila melanogaster glutathione transferase overexpressed in the sensory organs after exposure to bitter molecules in food

International audience

Marqueurs en addictologie et toxicomanies - Actualité et prospective

La deuxième édition de Biochimie médicale : marqueurs actuels et perspectives paraît trois ans seulement après la première, mais cette démarche des auteurs et coordonnateurs est pleinement justifiée. Cet ouvrage n'est pas un simple répertoire de molécules. C'est un outil pratique directement orienté vers les pathologies ou les dysfonctionnements d'organes à cibler. Et dans ce domaine, il convient d'être actuel et le plus complet possible. C'est pourquoi cette deuxième édition est à la fois actualisée des connaissances acquises en 2011 et enrichie de 7 nouveaux chapitres afin de compléter le panorama des biomarqueurs biochimiques de la première édition. La présentation des marqueurs y est or…

Transcriptional Regulation by Triiodothyronine of the UDP-glucuronosyltransferase Family 1 Gene Complex in Rat Liver

Abstract This study demonstrates that the expression of the phenol UDP-glucuronosyltransferase 1 gene (UGT1A1) is regulated at the transcriptional level by thyroid hormone in rat liver. Following 3,5,3′-triiodo-l-thyronine (T3) stimulation in vivo, there is a gradual increase in the amount of UGT1A1 mRNA with maximum levels reached 24 h after treatment. In comparison, induction with the specific inducer, 3-methylcholanthrene (3-MC), results in maximal levels of UGT1A1 mRNA after 8 h of treatment. In primary hepatocyte cultures, the stimulatory effect of both T3 and 3-MC is also observed. This induction is suppressed by the RNA synthesis inhibitor actinomycin D, indicating that neither induc…

Oxidative stress and xenobiotic detoxification enzymes in rat astrocytes: Correlations with brain aging

Meeting Abstract; International audience

Effets d’une exposition orale en Bisphenol A sur la préférence au salé et la structure de la glande sous-mandibulaire chez le rat mâle adulte

Effets d’une exposition orale en Bisphenol A sur la préférence au salé et la structure de la glande sous-mandibulaire chez le rat mâle adulte. Colloque PNR-PE

Metabolism of tresperimus by rat aorta semicarbazide-sensitive amine oxidase (SSAO).

Tresperimus (Cellimis), a new immunosuppressive agent, is mainly eliminated in the rat through metabolism, in which the oxidative deamination of the primary amine of the drug plays a major role. We have previously demonstrated in vivo the significant involvement of semicarbazide-sensitive amine oxidase (SSAO) in this reaction. Rat aorta, a tissue with one of the highest specific SSAO activities, was tested as a new in vitro model to elucidate tresperimus metabolism, using a combination of liquid chromatography/mass spectrometry (LC/MS) and high-performance liquid chromatography (HPLC) analyses. The metabolites resulting from the main metabolic pathway of the drug were formed in rat aorta ho…

P45 - Drosophila melanogaster glutathione transferase overexpressed in the sensory organs after exposure to bitter molecules in food

International audience

Influence of vitamin A status on the regulation of uridine (5′-)diphosphate-glucuronosyltransferase (UGT) 1A1 and UGT1A6 expression by L-triiodothyronine

The uridine (5′-)diphosphate-glucuronosyltransferases (UGT) are involved in the phase II of various xenobiotics and endogenous compounds. They are responsible for glucuronidation of many substrates, especially including bilirubin (UGT1A1) and phenolic compounds (UGT1A6). We previously showed that the expression of both isoforms is regulated at the transcriptional level by thyroid hormone in rat liver. In this present study, effects of vitamin A dietary intake (0, 1.72, 69 ug retinol acetate/g food) on the regulation of UGT1A1 and UGT1A6 activity and expression by 3,5,3′ triiodo-L-THYRONINE (l-T3) were examined in the same organ. Activities were determined toward bilirubin and 4-nitrophenol.…

Structural and enzymatic characterization of a Drosophila melanogaster glutathione transferase overexpressed in the sensory organs after exposure to bitter molecules in food

Glutathione transferases (GSTs) are ubiquitous key detoxification enzymes that catalyze the conjugation of glutathione to a large variety of xenobiotic chemical including odorants and sapid molecules. A previous study in Drosophila melanogaster demonstrated the existence of a GST specifically expressed in the antenna and involved in signal termination by catalyzing biotransformation of odorant molecules. Genomic analysis allows identifying forty GSTs in Drosophila melanogaster but their biochemistry is poorly documented. Here we demonstrated that among the GSTs, dmelGSTD2-2 was strongly and preferentially overexpressed in the sensory organs (antennae, proboscis, legs, wings) after an exposu…

Are taste preferences related to submandibular endocrine or exocrine secretions? A rodent study

National audience

Effect of oxidative stress on UDP-glucuronosyltransferases in rat astrocytes.

WOS:000309170300003; International audience; The present work reports data regarding effects of an induced oxidative stress on the mainly expressed isoforms of UDP-glucuronosyltransferases (UGTs) in the brain. UGT1A6 and UGT1A7 expression and enzymatic activities toward the 1-naphthol were analyzed in rat cultured astrocytes following the exposure for 48 h to redox-cycling xenobiotic compounds such as quinones and bipyridinium ions. The expression of NADPH:cytochrome P450 reductase and NAD(P)H:quinone oxidoreductase 1 (NQO1) was also investigated. Oxidative stress induced significant deleterious changes in astrocyte morphology, decreased cell viability and inhibited catalytic function of UG…