Metabolic profiling of rat brain and cognitive behavioral tasks: potential complementary strategies in preclinical cognition enhancement research.

In this study, the correlation between the metabolic profiles of rats undergoing cognition enhancement drug therapy and their associated cognitive behavioral outcomes were investigated. Male Lister Hooded rats were administered either with donepezil, galantamine, or vehicle and subjected to Atlantis watermaze training and novel object recognition tests. An UPLC/MS/MS method was developed to profile 21 neurologically related metabolites in the rat brains. Pharmacologically induced behavioral changes were compared subsequently with the metabolic fluctuations of neurologically related metabolites from multiple neurotransmitter pathways using multivariate and univariate statistical analyses. Significant improvements in cognitive behavioral outcomes were demonstrated in the rats administered with donepezil and galantamine using both AWM training (P < 0.05) and NOR (P < 0.05) tests as compared to those dosed with the vehicle. This corroborated with the significant elevation of eight prominent biomarkers after the cognitive enhancement therapy. An orthogonal partial least-squares discriminant analysis model generated using only the 8 metabolites identified as discriminating the drug-dosed rats from the vehicle-dosed rats gave a Q(2) = 0.566, receiver operator characteristic (ROC) AUC = 1.000, using 7-fold cross validation. Our study suggests that metabolic profiling of rat brain is a potential complementary strategy to the cognitive behavioral tasks for characterizing neurobiological responses to cognition enhancement drug testing.

A sensitive LC/MS/MS bioanalysis assay of orally administered lipoic acid in rat blood and brain tissue.

A sensitive liquid chromatography tandem mass spectrometry (LC/MS/MS) bioanalytical method was developed and validated to analyze lipoic acid (LA) in rat blood and brain samples. Ten mobile phase combinations were investigated during method development. Mobile phase combination of 0.1% acetic acid (pH 4 adjusted with ammonia solution)/acetonitrile was most optimum in terms of sensitivity and peak shape of LA and the internal standard, valproic acid. Sample extraction method was explored using liquid-liquid extraction and protein precipitation methods. Protein precipitation yielded the highest recovery of the analytes from blood and brain ranging from 92 to 115%. The lower limit of quantitation (LLOQ) of LA was 0.1ng/mL (0.485nM) in both blood and brain while on-column lower limit of detection (LLOD) was 0.03pg. The precision (% R.S.D.) ranged from 1.49 to 26.39% and 1.49 to 10.89% for intra- and inter-day assays, respectively. The accuracy ranged from 91.2 to 116.17% for intra-day assay and 102.68 to 114.33% for inter-day assay.

Investigation of the drug-drug interaction between alpha-lipoic acid and valproate via mitochondrial beta-oxidation.

PURPOSE: To investigate the potential drug-drug interaction (DDI) between lipoic acid (LA) and valproate (VA) via the mitochondrial beta-oxidation pathway in rats. METHODS: In vitro mitochondrial assays were performed to compare the biotransformation of VA to valproyl-CoA (VA-CoA), in the absence and presence of LA. In vitro microsomal and protein binding assays were performed to elucidate their potential DDI at the microsomal metabolism and distribution levels. A pharmacokinetic study was conducted in Lister Hooded rats to ascertain the in vivo DDI between LA and VA. RESULTS: LA was shown to decrease significantly (p < 0.05) the in vitro formation of VA-CoA in a concentration-dependent manner. Our in vitro assay results confirmed that there was minimal interaction between LA and VA in microsomal metabolism and protein binding. Based on the pharmacokinetic data, the absolute bioavailability of VA was determined to be 1.3 in the presence of LA. CONCLUSIONS: Our study demonstrated for the first time that there is a potential DDI between LA and VA at the mitochondrial beta-oxidation level. While further clinical study is essential, our preliminary finding suggested that medical practitioners need to be prudent when managing epileptic patients who are co-administered with both VA and LA.