Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters

PLoS One. 2015 Nov 10;10(11):e0141193. doi: 10.1371/journal.pone.0141193. eCollection 2015.

Abstract

VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA) coupled with high-performance liquid (HPLC) or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Weight / radiation effects
  • Cerebral Cortex / metabolism
  • Cholinergic Neurons / metabolism
  • Chromatography, Gel
  • Chromatography, High Pressure Liquid
  • Cricetinae
  • Enzyme-Linked Immunosorbent Assay
  • Hypothalamo-Hypophyseal System / physiology
  • Hypothalamus / metabolism
  • Male
  • Neuropeptides / physiology*
  • Organ Size / radiation effects
  • Peptide Fragments / metabolism
  • Phodopus / physiology*
  • Photoperiod*
  • Pituitary Gland / metabolism
  • Pituitary-Adrenal System / physiology
  • Protein Processing, Post-Translational / radiation effects*
  • RNA, Messenger / biosynthesis
  • Testis / physiology

Substances

  • Neuropeptides
  • Peptide Fragments
  • RNA, Messenger
  • VGF peptide

Grants and funding

This study was sponsored by the ARS (Autonomous Region of Sardinia) through the "Sardinia PO FSE 2007-1013" funds (the L.R. 7/2007 for the "Promotion of the Scientific Research and of the Technological Innovation in Sardinia"). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.