Up-regulation of rat myometrial phospholipases Cβ1 and Cβ3 correlates with increased term sensitivity to carbachol and oxytocin

Carbachol and oxytocin increased myometrial inositol phosphate production at term, enhancing uterine contractility.

• The potency of carbachol and oxytocin to induce myometrial inositol phosphate production was greater at term compared to earlier stages.
• Both agonists effectively increased contractions in the circular muscle but not in the longitudinal muscle.
• The maximal response to carbachol remained unchanged, while the response to oxytocin significantly increased at term.
• Increased responsiveness to carbachol and oxytocin was linked to the up-regulation of PLCbeta1 and PLCbeta3 enzymes.
• Administration of oestradiol during pregnancy raised PLCbeta1 and PLCbeta3 levels by 200-260%, while progesterone had no effect.
• Differences in the regulation of the phospholipase C pathway suggest distinct roles for longitudinal and circular uterine muscles during pregnancy.

AI simplified