Catecholamines are not linked to myometrial phospholipase C and uterine contraction in late pregnant and parturient mouse

• Published in: The Journal of physiology 2001-10, Vol.536 (1), p.123-131
• Main Authors: Mhaouty‐Kodja, Sakina, Houdeau, Eric, Cohen‐Tannoudji, Joëlle, Legrand, Chantal
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Antagonists - pharmacology; Animals; Cell Membrane - enzymology; Female; Gene Expression - physiology; Inositol Phosphates - biosynthesis; Isoenzymes - analysis; Isoenzymes - metabolism; Labor, Obstetric - physiology; Life Sciences; Mice; Mice, Inbred C57BL; Myometrium - enzymology; Norepinephrine - pharmacology; Oxytocin - pharmacology; Phenylephrine - pharmacology; Phospholipase C beta; Pregnancy; Propranolol - pharmacology; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, alpha-1 - genetics; Receptors, Adrenergic, alpha-1 - metabolism; Research Papers; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - analysis; Signal Transduction - physiology; Sympathomimetics - pharmacology; Type C Phospholipases - analysis; Type C Phospholipases - metabolism; Uterine Contraction - drug effects; Uterine Contraction - physiology
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1111/j.1469-7793.2001.00123.x

We investigated whether catecholamines through activation of α 1 -adrenergic receptors (α 1 -AR) are involved in mouse uterine contraction at parturition. Myometrial phospholipase C (PLC) activity and uterine contraction were measured in response to noradrenaline (NA), the specific α 1 -AR agonist phenylephrine (Phe) and oxytocin (OT). Using the reverse transcription-polymerase chain reaction RT-PCR, we detected the α 1a -AR subtype in late pregnant mouse myometrium. We also detected, by immunoblotting studies, PLCβ 1 , PLCβ 3 and different α-subunits of pertussis toxin-insensitive (Gα q/11 ) and -sensitive G proteins (Gα o/i3 , Gα i1/2 ). Phenylephrine and NA did not alter the myometrial inositol phosphate (Ins P ) production of late pregnant or parturient mouse. In similar conditions, OT increased Ins P production in a dose-dependent manner. Consistent with these results, only OT (10 μ m ) recruited PLCβ 1 and PLCβ 3 to myometrial plasma membranes. The OT-induced Ins P response was not altered by pertussis toxin (300 ng ml −1 , 2 h pretreatment), suggesting the involvement of a member of the Gα q family. Noradrenaline and Phe failed to increase uterine contraction at late pregnancy and at parturition. In contrast, OT induced uterine contraction in a dose-dependent manner with maximal increase (400 %) at a concentration of 1 μ m . The results indicate that OT receptors (OTR) but not α 1 -AR are linked to myometrial PLC activation and uterine contraction in late pregnant and parturient mouse. This discrepancy between mouse and other mammals could be attributed to the α 1 -AR subtype expressed in myometrium at this time.