Acute effects of phorbol esters on receptor-mediated IP3, cAMP, and progesterone levels in rat granulosa cells

J. S. Davis, L. L. Weakland, R. G. Coffey, L. A. West

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Luteinizing hormone (LH) stimulates the formation of adenosine 3',5'-cyclic monophosphate (cAMP) and inositol trisphosphate (IP3) in rat granulosa cells. This report describes the effects of protein kinase C activators on second messenger generation in isolated rat granulosa cells. The protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA) completely inhibited LH-stimulated inositol phosphate accumulation. The inhibitory effects of TPA were rapid (5-15 min) and concentration dependent with 50 nM TPA producing maximally inhibitory effects. However, 30-min incubations with 10-100 nM TPA had no effect on LH-stimulated cAMP or progesterone levels. The inhibitory effect of TPA could not be overcome by high concentrations of LH. TPA also inhibited gonadotropin-releasing hormone-stimulated phospholipase C activity, although to a much lesser extent. Increased inositol phosphate degradation and reduced inositol phospholipid synthesis were unlikely explanations for the effects of TPA. The results indicate that phorbol esters modulate the inositol phospholipid-phospholipase C transmembrane signaling system in rat granulosa cells. The results suggest that phorbol esters may alter the coupling of the hormone receptor complex to phospholipase C.

Original languageEnglish (US)
Pages (from-to)19/3
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume256
Issue number3
StatePublished - 1989

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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