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Bursal antisteroidogenic peptide alters the activity of steroidogenic enzymes in chicken granulosa cells.

Abstract：

:We have previously reported that a peptide from chicken bursa of Fabricius, bursal antisteroidogenic peptide (BASP), inhibits luteinizing hormone-stimulated progesterone biosynthesis by chicken ovarian granulosa cells. The objective of this study was to determine the site(s) of BASP inhibition within the steroidogenic pathway of chicken granulosa cells. The effects of BASP on key steroidogenic enzymes, including adenylyl cyclase (AC), phosphodiesterase, the cholesterol side-chain cleavage enzyme complex and 3 beta-hydroxysteroid dehydrogenase were determined. Luteinizing hormone (10 ng/tube) stimulated a fivefold increase in granulosa cell progesterone production that was inhibited by BASP (0.06, 0.12 or 0.25 bursal equivalents) in a dose-dependent manner. Luteinizing hormone stimulated a sixfold increase in cyclic 3',5'-adenosine monophosphate (cAMP) formation, and this increase was potentiated by BASP in a dose-dependent manner. In addition, BASP stimulated cAMP formation in the absence of luteinizing hormone without affecting progesterone production. The AC activator forskolin (0.1 mM) stimulated a 4.5-fold increase in progesterone synthesis, which was inhibited by BASP. In the presence of forskolin. BASP increased cAMP formation in a dose-dependent manner. A fivefold increase in progesterone synthesis induced by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (1.0 mM) was inhibited by BASP. In the presence of 3-isobutyl-1-methylxanthine, BASP increased cAMP formation in a dose-dependent manner. Finally, 22(R)-hydroxycholesterol (250, 500, 1,000, or 2,500 ng/tube) or pregnenolone (50, 100, 200, or 500 ng/tube) resulted in up to 15- or 10-fold increases in progesterone production, respectively. Increasing concentrations of BASP caused a dose-dependent suppression of the conversion of 22(R)-hydroxycholesterol, but not pregnenolone, to progesterone. The inhibition of steroidogenesis by BASP is not associated with reduced cAMP levels, and BASP appears to strongly stimulate AC activity. In addition, these findings suggest that BASP may limit the availability of progesterone precursors by inhibiting the activity of the cholesterol side-chain cleavage enzyme complex.

journal_name

Domest Anim Endocrinol

journal_title

Domestic animal endocrinology

authors

Dean CE,Byrd JA,Hargis BM

doi

10.1016/0739-7240(94)00007-n

subject

Has Abstract

pub_date

1995-01-01 00:00:00

pages

51-61

issue

eissn

0739-7240

issn

1879-0054

pii

073972409400007N

journal_volume

pub_type

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Bursal antisteroidogenic peptide alters the activity of steroidogenic enzymes in chicken granulosa cells.