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Photoperiod‐dependent regulation of carboxypeptidase D and E effects the selective processing of neuropeptides in the seasonal Siberian hamster (Phodopus sungorus)
Author(s) -
Helwig Michael,
Herwig Annika,
Heldmaier Gerhard,
Mercer Julian G,
Klingenspor Martin
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb542
Subject(s) - phodopus , hamster , neuropeptide , medicine , endocrinology , biology , photoperiodism , hypothalamus , neuropeptide y receptor , chemistry , biochemistry , receptor
Energy balance in seasonal animals such as the Siberian hamster is regulated by a complex hypothalamic neuropeptidergic network. Most of the neuropeptides within this network derive from biologically inactive peptide‐precursors and have to undergo extensive post‐translational processing including C‐terminal cleavage by carboxypeptidases D and E (CPD, CPE). We investigated the effect of photoperiod on the C‐terminal activation of energy balance‐related neuropeptides, alpha‐melanocyte stimulating hormone (α‐MSH) and β‐endorphin (β‐END), within the hypothalamus of short day (SD, 8h/16h light/dark) and long day (LD, 16h/8h light/dark) acclimated Siberian hamsters. We compared hypothalamic distribution of CPD, CPE, α‐MSH and β‐END using immunohistochemistry and measured enzyme activity of CPE and concentrations of its product, C‐terminally‐cleaved α‐MSH, by radioimmunoassay in SD and LD acclimated animals. In SD, immunoreactivity (‐ir) of CPD and CPE as well as CPE‐activity was up‐regulated along with a substantial increase in C‐terminally cleaved α‐MSH and β‐END‐ir. Our results suggest that in the Siberian hamster, CPE‐mediated cleavage of neuropeptides is tightly regulated by photoperiod and may therefore be a key event in the regulation of seasonal energy balance.