Modulation of phospholipase C pathway and level of Gq alpha/G11 alpha in rat myometrium during gestation.
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 at days 12 and 21 two- and threefold, respectively, with no alteration of muscarinic sites (M3 subtype). A similar increase could be detected in the production of inositol 1,4,5-trisphosphate, indicating the stimulation of a PLC degrading phosphatidylinositol 4,5-bisphosphate. AlF4- also enhanced PLC activation during gestation, suggesting pregnancy-related regulations that bypass receptor activation. Immunoreactive G proteins, Gq alpha and G11 alpha, and PLC-beta 3 were detected in all myometrial preparations. The amount of PLC-beta 3 was similar in day 0 and day 21 myometrium, although decreasing by 75% at midgestation. Of significance was the increased amount of Gq alpha in day 12 and day 21 myometrium (3- and 2-fold, respectively) which coincided with the enhanced phosphoinositide breakdown. The upregulation of Gq alpha may contribute to the enhanced PLC activity during pregnancy and at term.
Lajat
S
S
Centre National de la Recherche Scientifique Unité de Recherche Associée 1131, Université Paris Sud, Orsay, France.
Tanfin
Z
Z
Guillon
G
G
Harbon
S
S
D000818:Animals; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D009215:Myometrium / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism*
D010738:Type C Phospholipases; D019204:GTP-Binding Proteins