%0 Journal Article %T Neuropeptidomic analysis of the embryonic Japanese quail diencephalon %A Birger Scholz %A Henrik Alm %A Anna Mattsson %A Anna Nilsson %A Kim Kultima %A Mikhail M Savitski %A Maria F£¿lth %A Karl Sk£¿ld %A Bj£¿rn Brunstr£¿m %A Per E Andren %A Lennart Dencker %J BMC Developmental Biology %D 2010 %I BioMed Central %R 10.1186/1471-213x-10-30 %X We identified a total of 65 peptides whereof 38 were sufficiently present in all groups for statistical analysis. Age was the most defining variable in the data and sex had the least impact. Most identified peptides were more highly expressed in embryonic day 17. The top candidates for EE2 exposure and sex effects were neuropeptide K (downregulated by EE2 in males and females), gastrin-releasing peptide (more highly expressed in control and EE2 exposed males) and gonadotropin-inhibiting hormone related protein 2 (more highly expressed in control males and displaying interaction effects between age and sex). We also report a new potential secretogranin-2 derived neuropeptide and previously unknown phosphorylations in the C-terminal flanking protachykinin 1 neuropeptide.This study is the first larger study on endogenous peptides in the developing brain and implies a previously unknown role for a number of neuropeptides in middle to late avian embryogenesis. It demonstrates the power of label-free liquid chromatography mass spectrometry to analyze the expression of multiple endogenous peptides and the potential to detect new putative peptide candidates in a developmental model.Bird models have been instrumental to the overall understanding of neural sex differences and endocrine influences on brain development [1,2]. Japanese quail is a commonly used bird model for studying sex-specific brain development and behavior, especially the influence of the hormonal milieu during early brain development on sexual behaviour [3-5]. Sex-specific neural development has traditionally been associated with sex hormones produced by the gonads. Exogenous estrogen exposure before embryonic day 12 (ed12) causes demasculinization of the male sexual behaviour in Japanese quail [3,5], which shows the important role of sex hormones in brain differentiation. Several studies in songbirds have shown that there are exceptions to this classical model [6-9], implicating an intrinsic genetic influe %U http://www.biomedcentral.com/1471-213X/10/30