Metabolic profiling of cerebrospinal fluid (CSF) is a promising technique for studying brain diseases. Measurements should reflect the in vivo situation, so ex vivo metabolism should be avoided. To... Show moreMetabolic profiling of cerebrospinal fluid (CSF) is a promising technique for studying brain diseases. Measurements should reflect the in vivo situation, so ex vivo metabolism should be avoided. To investigate the effects of temperature (room temperature vs. 4 °C), centrifugation and ethanol, as anti-enzymatic additive during CSF sampling on concentrations of glutamic acid, glutamine and other endogenous amines. CSF samples from 21 individuals were processed using five different protocols. Isotopically-labeled alanine, isoleucine, glutamine, glutamic acid and dopamine were added prior to sampling to trace any degradation. Metabolomics analysis of endogenous amines, isotopically-labeled compounds and degradation products was performed with a validated LC-MS method. -phosphoethanolamine concentrations were also lower when ethanol was added. Degradation of isotopically-labeled compounds (e.g. glutamine to glutamic acid) was minor with no differences between protocols. Most amines can be considered stable during sampling, provided that samples are cooled immediately to 4 °C, centrifuged, and stored at - 80 °C within 2 h. The effect of ethanol addition for more unstable metabolites needs further investigation. This was the first time that labeled compounds were used to monitor ex vivo metabolism during sampling. This is a useful strategy to study the stability of other metabolites of interest. Show less
Endocannabinoids, a class of lipid messengers, have emerged as crucial regulators of synaptic communication in the central nervous system (CNS). Dysregulation of these compounds has been... Show moreEndocannabinoids, a class of lipid messengers, have emerged as crucial regulators of synaptic communication in the central nervous system (CNS). Dysregulation of these compounds has been implicated in many brain disorders. Although some studies have identified and quantified a limited number of target compounds, a method that provides comprehensive quantitative information on endocannabinoids and related N-acylethanolamines (NAEs) in CSF is currently lacking as measurements are challenging due to low concentrations under normal physiological conditions. Here we developed and validated a high-throughput nano liquid chromatography-electrospray ionization mass spectrometry (nano LC-ESI-MS/MS) platform for the simultaneous quantification of endocannabinoids (anandamide (AEA), 2-arachidonoyl glycerol (2-AG)), ten related NAEs and eight additional putatively annotated NAEs in human CSF. Requiring only 200 μL of CSF our method has limits of detection from 0.28 to 61.2 pM with precisions of RSD <15% for most compounds. We applied our method to CSF from 45 healthy humans and demonstrated potential age and gender effects on concentrations of endocannabinoids and NAEs. Notably, our results show that docosahexaenoyl ethanolamide (DHEA) concentrations increase with age in males. Our method may offer new opportunities to gain insight into regulatory functions of endocannabinoids in the context of (ab)normal brain function. Show less
Migraine is a common brain disorder characterized by recurrent attacks of severe headaches and other neurological symptoms. In one-third of patients headaches are accompanied by auras, which... Show moreMigraine is a common brain disorder characterized by recurrent attacks of severe headaches and other neurological symptoms. In one-third of patients headaches are accompanied by auras, which consist of transient visual and sensory disturbances, believed to be caused by cortical spreading depression (CSD). CSD is characterized by a wave of neuronal and glial depolarization with concomitant changes in metabolite concentrations in the brain and cerebrospinal fluid. It remains unknown whether CSD-induced brain metabolic changes can be captured outside the central nervous system, i.e., in peripheral fluids. This study investigated plasma metabolic changes in transgenic mice that harbor a gene mutation in voltage-gated CaV2.1 Ca(2+) channels previously identified in patients with familial hemiplegic migraine, a subtype of migraine with auras. The use of a mouse model allows investigation of molecular changes occurring shortly after CSD, which is notoriously difficult in patients. Capillary electrophoresis - mass spectrometry was used for the analysis of plasma samples to obtain, for the first time, a comprehensive view of molecular changes immediately after experimentally induced CSD. Multivariate data analysis showed a clear distinction between profiles of transgenic and wild-type animals after CSD. Two metabolites considered important for this discrimination were tentatively identified as being lysine and its by-product pipecolic acid with additional evidence provided by hydrophilic interaction chromatography combined with tandem mass spectrometry. The changed metabolites suggest a compensatory increase in GABAergic neurotransmission upon enhanced excitatory neurotransmission. These results show that CSD induces metabolic remodeling in transgenic migraine mice that can be captured and measured in plasma. Show less
