Identification and quantification of neuropeptides in naïve mouse spinal cord using mass spectrometry reveals [des‐Ser1]‐cerebellin as a novel modulator of nociception

Abstract

Neuropeptide transmitters involved in nociceptive processes are more likely to be expressed in the dorsal than the ventral horn of the spinal cord. This study was designed to examine the relative distribution of neuropeptides between the dorsal and ventral spinal cord in na€ ıve mice using liquid chromatography, high-resolution mass spectrometry. We identified and relatively quantified 36 well-characterized full-length neuropeptides and an additional 168 not previously characterized peptides. By extraction with organic solvents we identified seven additional full-length neuropeptides. The peptide [desSer1]-cerebellin (desCER), originating from cerebellin precursor protein 1 (CBLN1), was predominantly expressed in the dorsal horn. Immunohistochemistry showed the presence of CBLN1 immunoreactivity with a punctate cytoplasmic pattern in neuronal cell bodies throughout the spinal gray matter. The signal was stronger in the dorsal compared to the ventral horn, with most CBLN1 positive cells present in outer laminae II/III, colocalizing with calbindin, a marker for excitatory interneurons. Intrathecal injection of desCER induced a dose-dependent mechanical hypersensitivity but not heat or cold hypersensitivity. This study provides evidence for involvement of desCER in nociception and provides a platform for continued exploration of involvement of novel neuropeptides in the regulation of nociceptive transmission.

Neurochemical characterization of pERK-expressing spinal neurons in histamine-induced itch

“…However, we found no colocalization of pERK and calbindin (0/800) ( Fig. 5b–b” ); calbindin has been reported to be expressed by a subset of spinal excitatory interneurons 16 33 . Since both the Lmx1b and Calbindin are located in excitatory interneuron in the SDH, this seemingly paradoxical results led us to explore whether they label different populations of excitatory interneuron.…”

Transmission of Pruriceptive Signals

“…An indication of the complexity of the circuits in the spinal cord is provided by the demonstration of large number of transmitters that are present in this tissue (Su et al, 2014). Despite this apparent overwhelming complexity, significant headway has been made in unraveling the transmitters and cellular mechanisms involved in itch transmission.…”

Thermal Inactivation of Enzymes and Pathogens in Biosamples for MS Analysis

“…In a recent study [10], the distribution of neuropeptides in mouse spinal cord was investigated. Dorsal and ventral halves of the cervical and lumbar enlargements were isolated under a dissecting microscope.…”

“…While blood sampling is relatively rapid, tissue sampling is more complicated and may involve a considerable time period of physiological stress and ischemia. After tissue excision, further microscope dissection may be needed prior to downstream homogenization and analysis [10,11]. For both sample types, there are analytical targets undergoing rapid conversion making adequate sampling a challenge.…”