title: Detection and partial characterization of an anti-steroidogenic peptide from the humoral immune system of the chicken.
abstract: Phenomenological association of alterations of immune system function at the time of puberty (e.g. involution of the chicken bursa of Fabricius) has led to postulation that the humoral immune system may negatively affect the hypothalamo-adenohypophyseal-gonadal axis of the neonate. Presently, we examined the effect of an acidic aqueous bursa of Fabricius extract, derived from prepubescent chickens, on in vitro basal and LH-stimulated progesterone biosynthesis by isolated ovarian granulosa cells of the largest preovulatory chicken follicles (F1 and F2). Crude extracts of < 5kDa and > 3kDa inhibited LH-stimulated progesterone secretion (P < 0.05). The bioactive component was observed to be heat labile and is sensitive to the endopeptidases chymotrypsin, trypsin and papain. The peptide is not sensitive to the exopeptidase, aminopeptidase M. Partial purification by reversed phase HPLC resulted in a fraction capable of inhibiting in vitro steroidogenesis. This fraction suppressed LH-stimulated progesterone biosynthesis to approximately basal levels (79% suppression). Following removal of the peptide, granulosa cells were capable of LH-stimulated progesterone biosynthesis similar to control cells. Bursal extract significantly inhibited cAMP analog-stimulated progesterone biosynthesis. These data indicate that the anti-steroidogenic peptide derived from the chicken bursa of Fabricius is a single heat labile, amino terminally blocked peptide with bioactivity independent of the gonadotropin receptor of the granulosa cell.
authors.affiliation: Department of Poultry Science, Texas Agricultural Experiment Station, Texas A&M University System, College Station 77843.
authors.forename: J A
authors.initials: JA
authors.lastname: Byrd
authors.forename: T K
authors.initials: TK
authors.lastname: Hayes
authors.forename: M S
authors.initials: MS
authors.lastname: Wright
authors.forename: C E
authors.initials: CE
authors.lastname: Dean
authors.forename: B M
authors.initials: BM
authors.lastname: Hargis
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000917:Antibody Formation; D001681:Biological Assay; D001685:Biological Factors / Q000032:analysis / Q000502:physiology*; D002060:Bursa of Fabricius / Q000737:chemistry / Q000502:physiology*; D002478:Cells, Cultured; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism*; D010455:Peptides / Q000032:analysis / Q000502:physiology*; D011374:Progesterone / Q000096:biosynthesis*; D011863:Radioimmunoassay
chemical_list: D001685:Biological Factors; D010455:Peptides; D011374:Progesterone