Striatal Alterations of Secretogranin-1, Somatostatin, Prodynorphin, and Cholecystokinin Peptides in an Experimental Mouse Model of Parkinson Disease

Abstract

The principal causative pathology of Parkinson disease is the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta projecting to the striatum in the brain. The information regarding the expression of neuropeptides in parkinsonism is very limited. Here we have elucidated striatal neuropeptide mechanisms in experimental parkinsonism using the unilateral 6-hydroxydopamine model to degenerate dopamine neurons. A thoroughly controlled sample preparation technique together with a peptidomics approach and targeted neuropeptide sequence collections enabled sensitive detection, identification, and relative quantitation of a great number of endogenous neuropeptides. Previously not recognized alterations in neuropeptide levels were identified in the unilateral lesioned mice with or without subchronic 3,4-dihydroxy-L-phenylalanine administration, the conventional treatment of Parkinson disease. Several of these peptides originated from the same precursor such as secretogranin-1, somatostatin, prodynorphin, and cholecystokinin. Disease-related biotransformation of precursors into individual peptides was observed in the experimental model of Parkinson disease.

L-DOPA-induced dyskinesia is associated with regional increase of striatal dynorphin peptides as elucidated by imaging mass spectrometry

“…High mass accuracy (Table I). Although MS/MS based sequence identification of rodent aNeo, SP and enkephalin peptides have been reported in previous studies (44,45), the here presented data show the identification of several endogenous dynorphins that has not been described before (Fig. 2, Table I).…”

High Identification Rates of Endogenous Neuropeptides from Mouse Brain

“…This diversity of hydrophobicities makes it difficult to extract and preserve diverse neuropeptides in a single solution, such as the commonly used aqueous buffers. 2,27 The extraction procedure therefore has a crucial influence on the number and amount of peptides delivered to the LC−MS/MS analysis. 6 Remarkable losses of peptides in sample treatment have been previously observed during preservation.…”

“…It served as a data alignment and analysis tool with following parameters: m/z range from 300 to 1500 Da, time frame 5 min, m/z frame 0.01 Da with a peak intensity threshold 100 000. [DTyr, 27,36 D-Thr 32 ]-Neuropeptide Y (AA27−36) was used as internal standard for quality control. The normalized intensities of the 2000 most intensive features were plotted against their corresponding retention time (Rt).…”

Analysis of multiple quaternary ammonium compounds in the brain using tandem capillary column separation and high resolution mass spectrometric detection

“…Although LOD was not measured in the present study, we checked the MS signal to noise ratio of each analyte and found all of them were much higher than 10 in the brain samples, a high value allowing differential analysis. Similar to relative quantitative analysis studies commonly conducted in metabolomics and proteomics for endogenous substances [37][38][39], we monitored the CVs of analyte peak area/IS peak area ratios for quality control [40]. Using three technical replicates prepared from homogenized tissues (see Section 2), we were able to demonstrate the high precision of our method as shown by coefficients of variation (CVs) among measurements of under 17% for all the QACs (see Fig.…”