LC–MS/MS analysis of twelve neurotransmitters and amino acids in mouse cerebrospinal fluid

So far, analytical investigation of neuroactive molecules in cerebrospinal fluid (CSF) of rodent models has been limited to rats, given the intrinsic anatomic difficulties related to mice sampling and the corresponding tiny amounts of CSF obtained. This poses a challenge for the research in neuroscience, where many, if not most, animal models for neuronal disorders rely on mice. We introduce a new, sensitive and robust LC–MS/MS method to analyze a panel of twelve neuroactive molecules (NM) from mouse CSF (aspartic acid, serine, glycine, glutamate, γ-aminobutyric acid, norepinephrine, epinephrine, acetylcholine, dopamine, serotonin, histamine and its metabolite 1-metylhistamine). The paper describes the sampling procedure that allows the collection of 1−2 microliters of pure CSF from individual mouse specimens. To test its applicability, we challenged our method on the field, by sampling 37 individual animals, thus demonstrating its strength and reliability. Compared to other methods, our procedure does not involve any extraction nor derivatization steps: samples are simply diluted and analyzed as such by LC–MS/MS, using a dedicated ion pairing agent in the chromatographic setup. The panel of neuroactive molecules that is analyzed in a single run is also significantly higher compared to other methods. Given the number of mouse models used in the neuroscience research, we believe that our work will pave new ways to more advanced research in this field.