Characterization of Differential Cocaine Metabolism in Mouse and Rat through Metabolomics-Guided Metabolite Profiling

Abstract

Rodent animal models have been widely used for studying neurologic and toxicological events associated with cocaine abuse. It is known that the mouse is more susceptible to cocaine-induced hepatotoxicity (CIH) than the rat. However, the causes behind this species-dependent sensitivity to cocaine have not been elucidated. In this study, cocaine metabolism in the mouse and rat was characterized through LC-MS-based metabolomic analysis of urine samples and were further compared through calculating the relative abundance of individual cocaine metabolites. The results showed that the levels of benzoylecgonine, a major cocaine metabolite from ester hydrolysis, were comparable in the urine from the mice and rats treated with the same dose of cocaine. However, the levels of the cocaine metabolites from oxidative metabolism, such as N-hydroxybenzoylnorecgonine and hydroxybenzoylecgonine, differed dramatically between the two species, indicating species-dependent cocaine metabolism. Subsequent structural analysis through accurate mass analysis and LC-MS/ MS fragmentation revealed that N-oxidation reactions, including N-demethylation and N-hydroxylation, are preferred metabolic routes in the mouse, while extensive aryl hydroxylation reactions occur in the rat. Through stable isotope tracing and in vitro enzyme reactions, a mouse-specific a-glucoside of N-hydroxybenzoylnorecgonine and a group of aryl hydroxy glucuronides high in the rat were identified and structurally elucidated. The differences in the in vivo oxidative metabolism of cocaine between the two rodent species were confirmed by the in vitro microsomal incubations. Chemical inhibition of P450 enzymes further revealed that different P450-mediated oxidative reactions in the ecgonine and benzoic acid moieties of cocaine contribute to the species-dependent biotransformation of cocaine.

4‐Hydroxynonenal (HNE), a Toxic Aldehyde in French Fries from Fast Food Restaurants

“…Samples of the polar lipophilic DNPH adducts from FF were collected between 32 and 33 min from the HPLC column corresponding to the retention times of pure HNE-DNPH, and the pooled samples were subjected to LC/MS analysis. This analysis was completed by a previously published technique [33]. A 5 µL aliquot of the pooled samples was injected into a Waters Acquity ultra-performance liquid chromatography system (Milford, MA) and separated by a gradient of mobile phase ranging from water to 95 % aqueous acetonitrile containing 0.1 % formic acid over a 10 min run.…”

Evaluation ofin vitrometabolic systems for common drugs of abuse. 1. Cocaine

“…However, as has been noted in other studies, xenobiotic metabolism can vary both qualitatively and quantitatively between species (Kanamori et al, 2011;Roberts et al, 1991), suggesting caution when drawing conclusions based on cross-species assays. Species-dependent differences in COC metabolite profiles were recently examined by Yao et al, demonstrating not only quantitative and qualitative shifts in metabolism but also suggesting that the primary route of oxidative COC metabolism may differ between species (Yao et al, 2013).…”

Bundling arrows: improving translational CNS drug development by integrated PK/PD-metabolomics

“…Some studies showed how the metabolic phenotype of animal disease models for osteoarthritis and multiple sclerosis overlapped with the patients' metabolic phenotype, indicating the potential of metabolomics for interspecies translation [71,72,86,87]. Although no efforts have yet been made to compare the animal and human metabolic phenotypes after drug treatment in vivo, the rat and mouse metabolic phenotypes were compared to study their differential sensitivity to cocaine [88]. It was found that the aryl hydroxylation pathway was dominant in rats, causing increased excretion of cocaine, which was not the case in mice.…”