Neuropeptidomics of the Rat Habenular Nuclei

Abstract

Conserved across vertebrates, the habenular nuclei are a pair of small symmetrical structures in the epithalamus. The nuclei functionally link the forebrain and midbrain by receiving input from and projecting to several brain regions. Each habenular nucleus comprises two major asymmetrical subnuclei, the medial and lateral habenula. These subnuclei are associated with different physiological processes and disorders, such as depression, nicotine addiction, and encoding aversive stimuli or omitting expected rewarding stimuli. Elucidating the functions of the habenular nuclei at the molecular level requires knowledge of their neuropeptide complement. In this work, three mass spectrometry (MS) techniques-liquid chromatography (LC) coupled to Orbitrap tandem MS (MS/MS), LC coupled to Fourier transform (FT)-ion cyclotron resonance (ICR) MS/MS, and matrix-assisted laser desorption/ionization (MALDI) FT-ICR MS-were used to uncover the neuropeptide profiles of the rodent medial and lateral habenula. With the assistance of tissue stabilization and bioinformatics, a total of 262 and 177 neuropeptides produced from 27 and 20 prohormones were detected and identified from the medial and lateral habenula regions, respectively. Among these neuropeptides, 136 were exclusively found in the medial habenula, and 51 were exclusively expressed in the lateral habenula. Additionally, novel sites of sulfation, a rare post-translational modification, on the secretogranin I prohormone are identified. The results demonstrate that these two small brain nuclei have a rich and differentiated peptide repertoire, with this information enabling a range of follow-up studies.

Quantitative Characterization of the Neuropeptide Level Changes in Dorsal Horn and Dorsal Root Ganglia Regions of the Murine Itch Models

“…These processes include itch, learning, and reproduction; cardiovascular, gastrointestinal, and respiratory control; food and water intake; and analgesia and pain. 10 Neuropeptides are typically produced from the cleavage of larger precursor proteins, which is sometimes followed by enzymatic post-translational modifications (PTMs) such as Cterminal amidation, 11,12 acetylation, 13 phosphorylation, 14,15 sulfation, 16,17 and pyroglutamination. 18 Here liquid chromatography coupled to tandem mass spectrometry (LC−MS/MS) was used for the identification and quantification of neuropeptides.…”

Down-regulation of habenular calcium-dependent secretion activator 2 induces despair-like behavior

“…1 e and g), which encode DCV contents such as substance P, neurokinin A, neuropeptide K, and neurokinin B 34 . In addition, a recent peptidogenomic study has reported MHb producing 262 neuropeptides generated from 27 prohormones, such as somatostatin (SST), neuropeptide Y (NPY), and secretogranin 1–3, etc 20 .…”

“…Most of the input to the IPN are from the MHb 15 , 17 , and glutamatergic and cholinergic inputs from MHb project onto IPN neurons which are predominatly GABAergic 18 , 19 . The MHb also contains numerous neuropeptides such as tachykinins, VGF, neuropeptide Y, and secretogranin 1–3 20 , and CAPS2 is expressed in both MHbD and MHbV 5 , 6 , 21 . In this setting, CAPS2 may play a pivotal role in secretion of MHb neuropeptides.…”

Advances in High‐resolution Maldi Mass Spectrometry for Neurobiology

“…To further take advantage of the abilities of HRAM mass analyzers, a systematic and comprehensive neuropeptidomic investigation of the rat habenular nuclei using LC-ESI Orbitrap, LC-ESI-FTICR, and MALDI-FTICR-MS was performed by the Sweedler Lab. They identified and localized 262 neuropeptides from 27 prohormones in the medial habenula region and 177 neuropeptides produced from 20 prohormones in the lateral habenula region to better understand interaction in the brain and the role of the habenular nuclei (Yang et al, 2018). These largescale studies can be very powerful in characterizing regions of the brain to find potential biomarkers for disease, although targeted approaches can be valuable as well.…”