These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Intracellular signalling in the ovine pars tuberalis: an investigation using aluminium fluoride and melatonin.
    Author: Morgan PJ, Hastings MH, Thompson M, Barrett P, Lawson W, Davidson G.
    Journal: J Mol Endocrinol; 1991 Oct; 7(2):137-44. PubMed ID: 1657021.
    Abstract:
    The effect of aluminium fluoride (AlF4-) has been studied on inositol phosphate accumulation, calcium mobilization, cyclic AMP production and [2-125I]iodomelatonin binding in ovine pars tuberalis cells. These cells have high-affinity receptors for, and respond to, melatonin through inhibition of forskolin-stimulated adenylate cyclase. In the presence of 10 mM LiCl, AlF4- stimulated the net accumulation of inositol monophosphate and inositol bisphosphate. Consistent with these findings, AlF4- increased intracellular calcium; although this response was attenuated in calcium-depleted medium, indicating that the calcium response comprises both intracellular and extracellular components. Melatonin was ineffective on either basal or AlF4(-)-stimulated turnover of inositol phosphates. In concordance with the inositol phosphate response, melatonin had no effect on either the AlF4(-)-stimulated or the basal calcium levels. AlF4- blocked the increase in cyclic AMP stimulation by 1 microM forskolin, being as effective as melatonin, achieving approximately 90% inhibition. AlF4- also attenuated the binding of [2-125I]iodomelatonin to ovine pars tuberalis membranes by 15%. At the concentration used, these results are consistent with the interpretation that AlF4- activates many G protein-mediated responses, and thus imply that the inhibitory pathway for cyclic AMP predominates over the stimulatory arm, whereas there can only be a stimulatory pathway linked to phosphoinositide metabolism in ovine pars tuberalis cells.
    [Abstract] [Full Text] [Related] [New Search]