Oxytocin is hydrolyzed by an enzyme in human placenta that is identical to the oxytocinase of pregnancy serum

Naruki, M; Mizutani, Shigehiko; Goto, Keiko; Tsujimoto, Masafumi; Nakazato, Hiroshi; Itakura, Atsuo; Mizuno, Kazuo; Kurauchi, O.; Kikkawa, Fumitaka; Tsutsumi, Yutaka

doi:10.1016/0196-9781(95)02124-8

Cited by 17 publications

(7 citation statements)

References 21 publications

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“…Numerous studies have attempted to answer this question by measuring the “activity” of oxytocinase (LNPEP), an enzyme secreted by the placenta that degrades circulating OXT. 22 23 24 25 26 Quantitation of oxytocinase “activity” is done fluorometrically by measuring the amount of β-naphthylamine released from an arylamide substrate after incubation with plasma. 27 Here, we quantified for the first time, plasma oxytocinase level, rather than activity, and report that it is lower in obese women at baseline compared with nonobese women.…”

Section: Discussionmentioning

confidence: 99%

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

Tina

Juang

McElrath

et al. 2019

AJP Rep

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Objective To investigate differences in oxytocin (OXT) biodistribution between nonobese and obese parturients during labor. Study Design Patients with body mass index (BMI) of either ≥ 18 ≤ 24.9 kg/m2 (“nonobese”) or ≥ 30 kg/m2 (“obese”) undergoing elective induction of labor were included (N = 25 each). Blood samples were collected at baseline (T0), and 20 minutes after maximal OXT augmentation or adequate uterine contractions (T1) for OXT and oxytocinase assays. A mixed-model repeated-measures analysis of variance was used to test for group versus time interaction and analysis of covariance to detect a difference in OXT level at T1. Data presented as mean ± standard deviation or median (interquartile range), with p < 0.05 considered significant. Results The mean BMIs (kg/m2) were 22.1 ± 1.6 and 35.9 ± 5.1 in the nonobese and obese groups, respectively. No differences were observed in either the duration of OXT infusion, total dose of OXT, or plasma OXT (pg/mL) either at T0 or T1. However, plasma oxytocinase (ng/mL) was significantly lower at T0 (1.41 [0.67, 3.51] vs. 0.40 [0.29, 1.12]; p = 0.03) in the obese group. Conclusion We provide preliminary evidence that the disposition of OXT may not be different between obese and nonobese women during labor.

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Section: Discussionmentioning

confidence: 99%

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

Tina

Juang

McElrath

et al. 2019

AJP Rep

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“…P-LAP degrades the ring structure of OT at the peptide bond between Cys 1 and Tyr 2 and hydrolyzes the remaining structure in a stepwise fashion from the amino terminal. Prolylendopeptidase, and neutral endopeptidase are not involved in opening the ring structure of OT (Mizutani et al, 1985a;Naruki et al, 1996) indicating that only P-LAP should be regarded as an oxytocinase.…”

Section: Angiotensinases and Oxytocinasesmentioning

confidence: 93%

A new approach regarding the treatment of preeclampsia and preterm labor

Mizutani¹,

Wright

Kobayashi

2011

Life Sciences

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“…The other two proteases are not involved in opening the ring structure of OT [6, 34]. Thus, only P-LAP should be regarded as oxytocinase.…”

Section: Possible Role Of Oxytocinase (Vasopressinase)mentioning

confidence: 99%

Placental Leucine Aminopeptidase‐ and Aminopeptidase A‐Deficient Mice Offer Insight concerning the Mechanisms Underlying Preterm Labor and Preeclampsia

Mizutani¹,

Wright

Kobayashi

2010

BioMed Research International

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Preeclampsia and preterm delivery are important potential complications in pregnancy and represent the leading causes for maternal and perinatal morbidity and mortality. The mechanisms underlying both diseases remain unknown, thus available treatments (beta2-stimulants and magnesium sulfate) are essentially symptomatic. Both molecules have molecular weights less than 5–8 kDa, cross the placental barrier, and thus exert their effects on the fetus. The fetus produces peptides that are highly vasoactive and uterotonic and increase in response to maternal stress and with continued development. Fetal peptides are also small molecules that inevitably leak across into the maternal circulation. Aminopeptidases such as placental leucine aminopeptidase (P-LAP) and aminopeptidase A (APA) are large molecules that do not cross the placental barrier. We have shown that APA acts as an antihypertensive agent in the pregnant spontaneously hypertensive rat by degrading vasoactive peptides and as a result returns the animal to a normotensive state. P-LAP also acts as an antiuterotonic agent by degrading uterotonic peptides and thus prolongs gestation in the pregnant mouse. Given the ever increasing worldwide incidences of preeclampsia and preterm labor, it is imperative that new agents be developed to safely prolong gestation. We believe that the use of aminopeptidases hold promise in this regard.

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Oxytocin is hydrolyzed by an enzyme in human placenta that is identical to the oxytocinase of pregnancy serum

Cited by 17 publications

References 21 publications

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

A new approach regarding the treatment of preeclampsia and preterm labor

Placental Leucine Aminopeptidase‐ and Aminopeptidase A‐Deficient Mice Offer Insight concerning the Mechanisms Underlying Preterm Labor and Preeclampsia

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