Comparison Between Prostaglandin E2 and Oxytocin Actions on Pregnant Mouse Myometrium

Suzuki, Hiroyoshi; Kuriyama, Hirosi

doi:10.2170/jjphysiol.25.345

Cited by 19 publications

(12 citation statements)

References 14 publications

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“…The phasic contractions showed an all-or-none nature and were induced by Ca 2ϩ influx via L-type Ca 2ϩ channels, which reflects the spike activity induced by OT (37,47). This result corresponds to that in a report using rat myometrium (39).…”

Section: Discussionsupporting

confidence: 87%

“…Using other species besides mice, it is difficult to determine the genuine OTinduced uterine contractions because of a possible cross-reactivity of OT with arginine vasopressin V 1a receptor (V 1a R), which coexists in myometrium in humans and other species. In mouse uteri, we revealed that V 1a R was not detectable (17) and that OT did not induce any contractions in myometrium of otr knockout mice (50).Early investigations described in vitro contractions and membrane activity in the mouse myometrium (37,47). The influences of gestation (27), phosphatase inhibition (41), and intracellular Ca 2ϩ concentration (30) have subsequently been reported.…”

mentioning

confidence: 99%

“…Early investigations described in vitro contractions and membrane activity in the mouse myometrium (37,47). The influences of gestation (27), phosphatase inhibition (41), and intracellular Ca 2ϩ concentration (30) have subsequently been reported.…”

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confidence: 99%

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Oxytocin-induced phasic and tonic contractions are modulated by the contractile machinery rather than the quantity of oxytocin receptor

Kawamata¹,

Tonomura²,

Kimura³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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Kawamata M, Tonomura Y, Kimura T, Sugimoto Y, Yanagisawa T, Nishimori K. Oxytocin-induced phasic and tonic contractions are modulated by the contractile machinery rather than the quantity of oxytocin receptor. Am J Physiol Endocrinol Metab 292: E992-E999, 2007. First published December 5, 2006; doi:10.1152/ajpendo.00492.2006.-To investigate the relationship between the oxytocin (OT) receptor (OTR) quantity and the contractile features systematically, we measured the mRNA expression levels of OTR and L-type Ca 2ϩ channel ␣1C-subunit (␣1C) and examined the regulatory mechanisms of OT-induced phasic or tonic contractions of the longitudinal smooth muscles in mouse uteri. The mRNA expression of OTR in 19.0 G (19.0 days of gestation) was greater than those in nonpregnant phases, and that of ␣1C in estrus and 19.0 G was higher than in diestrus. OT-induced contractions sparsely occurred in diestrus. The OT-induced all-or-none-type phasic contractions at low concentrations were abolished by verapamil in both estrus and 19.0 G. OT-induced tonic contractions had similar pD2 values in both estrus and 19.0 G. However, the magnitude in 19.0 G was much greater than that in estrus. The large tonic contractions also occurred in PGF2␣ receptor (FP) knockout mice in 19.0 G despite a small amount of OTR. Verapamil and Y-27632 partially inhibited the tonic contractions in 19.0 G. Cyclopiazonic acid-induced tonic contractions were reciprocally decreased with the increase in the OT-induced ones in 19.0 G. These results indicate that the phasic contractions are dependent on ␣1C. The tonic contractions in 19.0 G are dependent on both Ca 2ϩ influxes via L-type Ca 2ϩ channels and store-operated Ca 2ϩ channels, and the force is augmented by the Rho signal pathway, which increases the Ca 2ϩ sensitivity. Thus the uterine contractions are mainly controlled by the modification of contractile signal machinery rather than simply by the OTR quantity.oxytocin; uterus; contraction; receptor quantity; mouse OXYTOCIN (OT) is a well-known neurohypophysial hormone that stimulates uterine contractions to facilitate parturition (11). The near-term myometrium is extremely sensitive to OT, and the increased responsiveness to OT occurs in parallel with an increase in the number of uterine OT binding sites in rats (6, 42), humans (7), rabbits (28, 29), and cows (8). A corresponding increase in uterine OT receptor (OTR) mRNA in late pregnancy and at parturition has been reported in rats (23,26,38), humans (21), cows (13), and sheep (51, 55). In human uterus at term, the sensitivity to OT is 200-to 1,000-fold greater than that during the menstrual cycle (1). Thus, although there has not yet been conclusive evidence, it has been believed that the sensitivity to OT depends on the OTR quantity.OT induces phasic or tonic contractions in myometrium. Phasic contractions are essential for the successful progression of labor, whereas tonic contractions may contribute to prevent atonic bleeding after parturition. During the course of parturition, prolonged tonic cont...

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Section: Discussionsupporting

confidence: 87%

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confidence: 99%

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Oxytocin-induced phasic and tonic contractions are modulated by the contractile machinery rather than the quantity of oxytocin receptor

Kawamata¹,

Tonomura²,

Kimura³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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“…Although OXT is a strong uterotonin and is considered to drive parturition, the previous observations unexpectedly and clearly prove that OXT is not essential for labor in mice. In contrast, Oxtr mRNA expression in the uterus is up-regulated dramatically at term (11), uterine sensitivity to OXT increases just before parturition (12,13), and OXTR antagonists delay parturition in mice (14), suggesting an indispensable role for OXTR in mouse parturition. We therefore suspected that a redundant signaling through OXTR during parturition might compensate for the absence of OXT in Oxt Ϫ/Ϫ mice.…”

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confidence: 94%

Pervasive social deficits, but normal parturition, in oxytocin receptor-deficient mice

Takayanagi

Yoshida

Bielsky

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

697

596

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The oxytocin receptor (OXTR) and its ligand, oxytocin (OXT), regulate reproductive physiology (i.e., parturition and lactation) and sociosexual behaviors. To define the essential functions of OXTR, we generated mice with a null mutation in the Oxtr gene (Oxtr ؊/؊ ) and compared them with OXT-deficient (Oxt ؊/؊ ) mice. Oxtr ؊/؊ mice were viable and had no obvious deficits in fertility or reproductive behavior. Oxtr ؊/؊ dams exhibited normal parturition but demonstrated defects in lactation and maternal nurturing. Infant Oxtr ؊/؊ males emitted fewer ultrasonic vocalizations than wild-type littermates in response to social isolation. Adult Oxtr ؊/؊ males also showed deficits in social discrimination and elevated aggressive behavior. Ligand Oxt ؊/؊ males from Oxt ؊/؊ dams, but not from Oxt ؉/؊ dams, showed similar high levels of aggression. These data suggest a developmental role for the OXT͞OXTR system in shaping adult aggressive behavior. Our studies demonstrate that OXTR plays a critical role in regulating several aspects of social behavior and may have important implications for developmental psychiatric disorders characterized by deficits in social behavior.lactation ͉ maternal behavior ͉ ultrasonic vocalization ͉ social discrimination ͉ aggressive behavior

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“…The smooth muscle membrane of the mouse uterus shows an anomalous rectifying property when the membrane is depolarized by 10-15 mV from the resting membrane potential (Suzuki & Kuriyama, 1975b). Therefore the reduction in amplitude of electrotonic potential during the ATP-induced depolarization indicates an increase in ionic conductance of the membrane.…”

Section: Atp-induced Depolarization Of the Membranementioning

confidence: 99%

Electrical responses of smooth muscle cells of the mouse uterus to adenosine triphosphate.

Ninomiya¹,

Suzuki²

1983

The Journal of Physiology

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SUMMARY1. Electrical responses of the smooth muscle cells to ATP were recorded in the longitudinal muscle of mouse myometrium, using intracellular micro-electrodes.2. ATP (> 10-7 M) dose-dependently produced a biphasic change in the membrane potential, an initial hyperpolarization (20-30 see) and then a depolarization. This effect of ATP was observed in all stages of gestation. The initial hyperpolarization was more quickly desensitized than the depolarization.3. Application of ATP for a short period (10 see) produced only the initial hyperpolarization; the amplitude was dose-dependently increased.4. During the ATP-induced hyperpolarization and the depolarization, generation of spike potentials was suppressed and enhanced, respectively. Strong outward current restored the spike generation during hyperpolarization.5. During the ATP-induced hyperpolarization, the membrane resistance was decreased. The amplitude of the hyperpolarization was increased in low [K]o solution and decreased in high [K]o solutions.6. Pre-treatment with TEA (1 mM), procaine (1 mM), 4-aminopyridine (0 5 mM) or apamin (2 x 10-7 M) did not, but TEA (5-10 mM) did suppress the ATP-induced hyperpolarization. Involvement of endogenous catecholamines, cyclic AMP, prostaglandins or acetylcholine in the ATP responses was ruled out.7. During the ATP-induced depolarization, the membrane resistance was reduced. In low [Na]0 solutions, the muscle membrane was depolarized and the amplitude of ATP-induced depolarization was reduced. In sodium-free solution, ATP produced only the initial hyperpolarization.8. It was concluded that the electrical responses ofthe smooth muscle cells of mouse myometrium to ATP consist of two components: an initial hyperpolarization with increase in the potassium conductance and a depolarization with increase in the sodium conductance.

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Comparison Between Prostaglandin E2 and Oxytocin Actions on Pregnant Mouse Myometrium

Cited by 19 publications

References 14 publications

Oxytocin-induced phasic and tonic contractions are modulated by the contractile machinery rather than the quantity of oxytocin receptor

Oxytocin-induced phasic and tonic contractions are modulated by the contractile machinery rather than the quantity of oxytocin receptor

Pervasive social deficits, but normal parturition, in oxytocin receptor-deficient mice

Electrical responses of smooth muscle cells of the mouse uterus to adenosine triphosphate.

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