Regulation of oxytocin-induced phosphoinositide breakdown in adipocytes by adenosine, isoproterenol and insulin

Horng Mo Lee, John N. Fain

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

In rat adipocytes, the breakdown of phosphoinositides labelled by a 3 h incubation with [3H]inositol resulted in the accumulation of labelled inositol mono-, bis- and trisphosphates in the presence of oxytocin, vasotocin or vasopressin. Oxytocin at a concentration of 1 nM markedly increased phosphoinositide breakdown. Incubation of adipocytes both during the 3 h labelling and the 10 min breakdown period in a low adenosine medium (presence of adenosine deaminase) or high adenosine medium (presence of 0.1 μM N6-(phenylisopropyl)adenosine) (PIA) did not affect basal or ligand-stimulated phosphoinositide breakdown. The addition of 1 μM PIA only during the measurement of phosphoinositide breakdown variably stimulated basal breakdown but significantly potentiated that due to oxytocin. Isoproterenol similarly had little effect on basal but inhibited oxytocin stimulation of phosphoinositide breakdown. Insulin did not affect basal or ligand-stimulated phosphoinositide breakdown in the low or high adenosine medium. However, in adipocytes incubated in the absence of added adenosine deaminase or PIA, insulin stimulated basal accumulation of inositol phosphates by about 20% and inhibited that due to oxytocin by about 20%. There was no significant effect of insulin on the stimulation by vasopressin or vasotocin of phosphoinositide breakdown. These results indicate that, in adipocytes, phosphoinositide breakdown stimulated by oxytocin is enhanced by adenosine, inhibited by isoproterenol and, under some conditions is inhibited by insulin.

Original languageEnglish
Pages (from-to)73-79
Number of pages7
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Volume1013
Issue number1
DOIs
Publication statusPublished - Sep 4 1989
Externally publishedYes

Fingerprint

Oxytocin
Phosphatidylinositols
Isoproterenol
Adipocytes
Adenosine
Insulin
Vasotocin
Adenosine Deaminase
Inositol
Vasopressins
Ligands
Inositol Phosphates

Keywords

  • Adenosine
  • Adipocyte
  • Catecholamine
  • Insulin
  • Oxytocin
  • Phosphoinositide

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology

Cite this

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title = "Regulation of oxytocin-induced phosphoinositide breakdown in adipocytes by adenosine, isoproterenol and insulin",
abstract = "In rat adipocytes, the breakdown of phosphoinositides labelled by a 3 h incubation with [3H]inositol resulted in the accumulation of labelled inositol mono-, bis- and trisphosphates in the presence of oxytocin, vasotocin or vasopressin. Oxytocin at a concentration of 1 nM markedly increased phosphoinositide breakdown. Incubation of adipocytes both during the 3 h labelling and the 10 min breakdown period in a low adenosine medium (presence of adenosine deaminase) or high adenosine medium (presence of 0.1 μM N6-(phenylisopropyl)adenosine) (PIA) did not affect basal or ligand-stimulated phosphoinositide breakdown. The addition of 1 μM PIA only during the measurement of phosphoinositide breakdown variably stimulated basal breakdown but significantly potentiated that due to oxytocin. Isoproterenol similarly had little effect on basal but inhibited oxytocin stimulation of phosphoinositide breakdown. Insulin did not affect basal or ligand-stimulated phosphoinositide breakdown in the low or high adenosine medium. However, in adipocytes incubated in the absence of added adenosine deaminase or PIA, insulin stimulated basal accumulation of inositol phosphates by about 20{\%} and inhibited that due to oxytocin by about 20{\%}. There was no significant effect of insulin on the stimulation by vasopressin or vasotocin of phosphoinositide breakdown. These results indicate that, in adipocytes, phosphoinositide breakdown stimulated by oxytocin is enhanced by adenosine, inhibited by isoproterenol and, under some conditions is inhibited by insulin.",
keywords = "Adenosine, Adipocyte, Catecholamine, Insulin, Oxytocin, Phosphoinositide",
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AU - Lee, Horng Mo

AU - Fain, John N.

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N2 - In rat adipocytes, the breakdown of phosphoinositides labelled by a 3 h incubation with [3H]inositol resulted in the accumulation of labelled inositol mono-, bis- and trisphosphates in the presence of oxytocin, vasotocin or vasopressin. Oxytocin at a concentration of 1 nM markedly increased phosphoinositide breakdown. Incubation of adipocytes both during the 3 h labelling and the 10 min breakdown period in a low adenosine medium (presence of adenosine deaminase) or high adenosine medium (presence of 0.1 μM N6-(phenylisopropyl)adenosine) (PIA) did not affect basal or ligand-stimulated phosphoinositide breakdown. The addition of 1 μM PIA only during the measurement of phosphoinositide breakdown variably stimulated basal breakdown but significantly potentiated that due to oxytocin. Isoproterenol similarly had little effect on basal but inhibited oxytocin stimulation of phosphoinositide breakdown. Insulin did not affect basal or ligand-stimulated phosphoinositide breakdown in the low or high adenosine medium. However, in adipocytes incubated in the absence of added adenosine deaminase or PIA, insulin stimulated basal accumulation of inositol phosphates by about 20% and inhibited that due to oxytocin by about 20%. There was no significant effect of insulin on the stimulation by vasopressin or vasotocin of phosphoinositide breakdown. These results indicate that, in adipocytes, phosphoinositide breakdown stimulated by oxytocin is enhanced by adenosine, inhibited by isoproterenol and, under some conditions is inhibited by insulin.

AB - In rat adipocytes, the breakdown of phosphoinositides labelled by a 3 h incubation with [3H]inositol resulted in the accumulation of labelled inositol mono-, bis- and trisphosphates in the presence of oxytocin, vasotocin or vasopressin. Oxytocin at a concentration of 1 nM markedly increased phosphoinositide breakdown. Incubation of adipocytes both during the 3 h labelling and the 10 min breakdown period in a low adenosine medium (presence of adenosine deaminase) or high adenosine medium (presence of 0.1 μM N6-(phenylisopropyl)adenosine) (PIA) did not affect basal or ligand-stimulated phosphoinositide breakdown. The addition of 1 μM PIA only during the measurement of phosphoinositide breakdown variably stimulated basal breakdown but significantly potentiated that due to oxytocin. Isoproterenol similarly had little effect on basal but inhibited oxytocin stimulation of phosphoinositide breakdown. Insulin did not affect basal or ligand-stimulated phosphoinositide breakdown in the low or high adenosine medium. However, in adipocytes incubated in the absence of added adenosine deaminase or PIA, insulin stimulated basal accumulation of inositol phosphates by about 20% and inhibited that due to oxytocin by about 20%. There was no significant effect of insulin on the stimulation by vasopressin or vasotocin of phosphoinositide breakdown. These results indicate that, in adipocytes, phosphoinositide breakdown stimulated by oxytocin is enhanced by adenosine, inhibited by isoproterenol and, under some conditions is inhibited by insulin.

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