Effects of Prostaglandin E2 and Progesterone on Rat Brain Synaptosomal Plasma Membranes

  1. Derek Chadwick Organizer and
  2. Kate Widdows
  1. George Deliconstantinos

Published Online: 28 SEP 2007

DOI: 10.1002/9780470513989.ch11

Ciba Foundation Symposium 153 - Steroids and Neuronal Activity

Ciba Foundation Symposium 153 - Steroids and Neuronal Activity

How to Cite

Deliconstantinos, G. (2007) Effects of Prostaglandin E2 and Progesterone on Rat Brain Synaptosomal Plasma Membranes, in Ciba Foundation Symposium 153 - Steroids and Neuronal Activity (eds D. Chadwick and K. Widdows), John Wiley & Sons, Ltd., Chichester, UK. doi: 10.1002/9780470513989.ch11

Author Information

  1. Department of Experimental Physiology, University of Athens, Medical School, GR-115 27 Athens, Greece

Publication History

  1. Published Online: 28 SEP 2007

ISBN Information

Print ISBN: 9780471926894

Online ISBN: 9780470513989

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Keywords:

  • prostaglandin E2;
  • progesterone;
  • arrhenius-type plots;
  • synaptosomal plasma membranes;
  • sex steroid interactions

Summary

The lipid fluidity of rat brain synaptosomal plasma membranes (SPM) labelled with 1,6-diphenyl-1,3,5-hexatriene (DPH) was increased by prostaglandin E2 (PGE2) and decreased by progesterone, as indicated by steady-state fluorescence anisotropy [(ro/r)−1]−1. Arrhenius-type plots of [(ro/r)−1] indicated a lipid phase separation of SPM at ≈23.5°C which was reduced to ≈18.1°C by PGE2 and increased to ≈34.6°C by progesterone. Treatment of SPM by PGE2 and progesterone caused an increase of the lipid phase separation to ≈32.4°C. Arrhenius plots of Na+/K+-ATPase activity in control SPM exhibited a break point at ≈23.1°C which was reduced to ≈17.8°C by PGE2 and increased to ≈32.6°C by progesterone. SPM treated with PGE2 plus progesterone showed an increased break point at ≈29.3°C. Na+/K+-ATPase activity was increased at a PGE2 concentration range between 0.1 and 3 µM; higher concentrations (up to 10 µM) led to a gradual inhibition of enzyme activity. Progesterone (0.1–10 µM) and PGE2 plus progesterone both produced a gradual decrease in enzyme activity. The allosteric inhibition of Na+/K+-ATPase by fluoride (F) (as reflected by changes in the Hill coefficient) was modulated by PGE2 and progesterone. The perturbations of membrane lipid structure and changes in membrane fluidity provide a basis for suggesting an independent non-genomic mechanism for the progesterone-induced alterations in the effects of PGE2 on brain function.