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…

Real time monitoring of the metabolic capacity of ex-vivo rat olfactory mucosa by on-line PTR-MS

Real time monitoring of the metabolic capacity of ex-vivo rat olfactory mucosa by on-line PTR-MS. Congrès français de Spectrométrie de Masse et d'Analyse Protéomique (SMAP 2015)

Odorant metabolizing enzymes in the peripheral olfactory process

Odorant metabolizing enzymes in the peripheral olfactory process

Temporal changes in free iron levels after brain ischemia

Whereas iron chelators have been proposed as therapeutic agents in stroke, changes in free iron levels have never been explored after focal brain ischemia. Therefore, free and total iron levels in cortical tissue and free iron levels in plasma were measured before and after (1, 4 and 24h) photothrombotic occlusion of cortical vessels in rats. Brain ferritin expression and localization were also investigated before and after (24, 72 and 192 h) occlusion. The results showed that free iron remained below detectable levels in plasma and that the lesion exhibited high levels of free and total iron. As compared to contralateral values, free iron levels in ischemic core and penumbra increased (+50…

Characterization of rat glutathione transferases in olfactory mucus and epithelium

International audience

Odorant metabolism in olfactory mucus: characterization and impact on olfactory perception

New insights in vertebrate >

International audience

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

National audience

Implication des enzymes dans la perception chimio-sensorielle : une piste dans les troubles olfacto-gustatifs induits par des xénobiotiques ?

International audience

Aroma volatile metabolites at olfactory mucosa level evidenced by in vitro PTR-Tof-MS studies

International audience; Olfactory mucosa can metabolize odorants through various enzymatic mechanisms participating in their clearance and therefore in the termination of the olfactory signal. Preliminary ex-vivo studies using headspace-GC revealed the formation of volatile metabolites when odorant molecules were injected above a fresh explant of rat olfactory mucosa. However, this method did not allow accessing the data during the first five minutes of contact between the odorant and the mucosa, thus limiting the olfactory biological significance. Using a direct-injection mass spectrometry technique (PTR-MS) we have been able for the first time to investigate the first moments of the enzym…

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…

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…

Odorant-odorant metabolic competitions: ex vivo inhibition of the mammary pheromone catabolism

International audience

New insights in vertebrate 'biotransfolfaction'

International audience

Odorants' metabolism in Human: a critical role in odor perception revealed

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…

Role of CYTOCHROME p450 in the perception of caffeine in Drosophila melanogaster

Poster

Rôle des enzymes du métabolisme des xénobiotiques dans la perception de la caféine chez la drosophile

National audience; Les animaux ont développé des systèmes de communication avec leur environnement indispensables à leur survie et leur reproduction. Les systèmes chimiosensoriels gustatifs et olfactifs détectent et transmettent au niveau central les informations chimiques de l’environnement (xénobiotique) afin que l’individu distingue les sources alimentaires des substances toxiques et reconnaisse ses proies de ses congénères. Ces systèmes, pour être efficaces, doivent être très sensibles et discriminants, et éviter la saturation des récepteurs. Dans l’espace péri-récepteur, les enzymes du métabolisme des xénobiotiques (EMX), impliquées normalement dans la détoxication, pourraient égalemen…

Caffeine metabolism in Drosophila melanogaster

International audience

Role of xenobiotic metabolizing enzymes in the perception of caffeine in Drosophila melanogaster

Poster

Role of CYP6d5 in the metabolism and the sensory perception of caffeine in Drosophila melanogaster

National audience

Interactions between odorants and glutathione transferases in the human olfactory cleft

AbstractXenobiotic metabolizing enzymes and other proteins, including odorant-binding proteins located in the nasal epithelium and mucus, participate in a series of processes modulating the concentration of odorants in the environment of olfactory receptors (ORs) and finely impact odor perception. These enzymes and transporters are thought to participate in odorant degradation or transport. Odorant biotransformation results in 1) changes in the odorant quantity up to their clearance and the termination of signaling and 2) the formation of new odorant stimuli (metabolites). Enzymes, such as cytochrome P450 and glutathione transferases (GSTs), have been proposed to participate in odorant clea…