Analysis of inositol phosphate metabolism by capillary electrophoresis electrospray ionization mass spectrometry

The analysis of myo-inositol phosphates (InsPs) and myo-inositol pyrophosphates (PP-InsPs) is a daunting challenge due to the large number of possible isomers, the absence of a chromophore, the high charge density, the low abundance, and the instability of the esters and anhydrides. Given their importance in biology, an analytical approach to follow and understand this complex signaling hub is desirable. Here, capillary electrophoresis (CE) coupled to electrospray ionization mass spectrometry (ESI-MS) is implemented to analyze complex mixtures of InsPs and PP-InsPs with high sensitivity. Stable isotope labeled (SIL) internal standards allow for matrix-independent quantitative assignment. The method is validated in wild-type and knockout mammalian cell lines and in model organisms. SIL-CE-ESI-MS enables the accurate monitoring of InsPs and PP-InsPs arising from compartmentalized cellular synthesis pathways, by feeding cells with either [13C6]-myo-inositol or [13C6]-D-glucose. In doing so, we provide evidence for the existence of unknown inositol synthesis pathways in mammals, highlighting the potential of this method to dissect inositol phosphate metabolism and signalling

5-HT1A receptor agonist-mediated protection from MPTP toxicity in mouse and macaque models of Parkinson's disease

Excitotoxicity-mediated cell death is involved in Parkinson's disease (PD). 5-HT1A receptor agonists can protect from such mechanisms. The current study demonstrates that the 5-HT1A agonists BAY 639044 and repinotan have neuroprotective effects in a subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. In addition, we also show that both compounds delay the appearance of parkinsonian motor abnormalities in a MPTP monkey model that recapitulates the progressive nature of PD. Thus, BAY 639044 or repinotan treatment was initiated when there was 30% neuronal death in the substantia nigra pars compacta, and nerve terminal loss in the striatum was 40%, i.e., compatible with the clinical situation where early symptomatic patients would receive such a treatment. The delay in appearance of parkinsonian motor abnormalities is a consequence of partial neuroprotection of nigrostriatal dopamine neurons, both at neuronal and terminal levels as shown for BAY 639044. These results suggest that 5-HT1A agonists, such as BAY 639044, may protect from neurodegeneration and delay the worsening of motor symptoms in Parkinson patients. © 2006.Peer Reviewe