Melatonin suppresses the induction of AP-1 transcription factor components in the pars tuberalis of the pituitary

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In ovine pars tuberalis cells which express high affinity Mel la melatonin receptors, the ability of melatonin to directly stimulate or inhibit AP-1 transcription factor gene expression was studied. Effects of melatonin upon mRNA expression by forskolin, serum and IGF-1 were also investigated. Northern analysis showed melatonin had no direct stimulatory nor inhibitory effect upon transcription or translation. Melatonin was able to significantly inhibit forskolin-stimulated induction of c-fos and jun B mRNA whilst forskolin had no effect upon c-jun or jun D. Induction of c-Fos translation by forskolin was also inhibited by melatonin. Serum induced c-fos and c-jun, but melatonin was unable to affect these changes. Similarly IGF-1 stimulated c-fos and melatonin had no effect upon this induction. From these results it can be concluded that melatonin has no independent effects on expression of the AP-1 genes, rather its primary function is to inhibit cell activities through cyclic AMP-dependent routes of gene activation.

Original languageEnglish
Pages (from-to)71-80
Number of pages10
JournalMolecular and Cellular Endocrinology
Issue number1
Publication statusPublished - 14 Oct 1996


  • melatonin
  • pars tuberalis
  • gene expression
  • c-fos
  • AP-1
  • pituitary
  • ovine pituitary
  • adenylate-cyclase
  • protein-kinase
  • FOS proteins
  • cells
  • secretion
  • prolactin
  • signal
  • acid
  • Jun

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