Modulation of the phospholipase c pathway and the level of
gq[alpha]/ g11[alpha] in rat myometrium during gestation.
Lajat, Sandrine, Zahra Tanfin, Gilles Guillon, and Simone Harbon.
Endocrinologie et R[acute]egulations Cellulaires, CNRS URA 1131,
Bat 432, Universit[acute]e Paris Sud, 91405 ORSAY Cedex, FRANCE,
*Unit[acute]e INSERM U401, centre CNRS-INSERM de Pharmacologie
-Endocrinologie, route de la Cardonille, 34094 Montpellier, FRANCE
APStracts 3:0125C, 1996.
The regulation of the receptor-G protein-Phospholipase C (PLC) cascade
was investigated in rat myometrium at midgestation (day 12) and at
term (day 21) comparatively to the estrogen-treated tissue (day 0).
Carbachol-mediated generation of [3H] inositol phosphates, was
insensitive to Pertussis toxin and was enhanced, in day 12 and day
21, 2-fold and 3-fold respectively with no alteration of muscarinic
sites (M3 subtype). A similar increase could be detected in the
production of Ins(1,4,5)P3 indicating the stimulation of a PLC
degrading PtdInsP2. AlF4- also enhanced PLC activation during
gestation suggesting pregnancy-related regulations which bypass
receptor activation. Immunoreactive G-proteins, Gqa and G11a, and
PLC[beta]3 were detected in all myometrial membranes. The amount of
PLC[beta]3 was similar in day 0 and day 21 although decreasing by 75%
at midgestation. Of significance was the increased amount of Gqa in
day 12 and day 21 (3- and 2-fold respectively) which coincided with
the enhanced phosphoinositide breakdown. The up-regulation of Gqa may
contribute to the enhanced PLC activity during pregnancy and at term.
Received 31 January 1996; accepted in final form 5 Arpil 1996.
APS Manuscript Number C61-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 23 April 96