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Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization: an In-vitro Analysis of Oxytocin Receptor Expression and Signaling

Primary Purpose

Postpartum Hemorrhage

Status
Recruiting
Phase
Not Applicable
Locations
Canada
Study Type
Interventional
Intervention
Oxytocin
Sponsored by
Samuel Lunenfeld Research Institute, Mount Sinai Hospital
About
Eligibility
Locations
Arms
Outcomes
Full info

About this trial

This is an interventional treatment trial for Postpartum Hemorrhage focused on measuring Uterine contraction, Oxytocin desensitization

Eligibility Criteria

16 Years - 40 Years (Child, Adult)FemaleAccepts Healthy Volunteers

Inclusion Criteria:

  • Patients who give written consent to participate in this study
  • Patients with gestational age 37-41 weeks
  • Non-laboring patients, not exposed to exogenous oxytocin
  • Patients requiring primary Cesarean delivery or first repeat Cesarean delivery

Exclusion Criteria:

  • Patients who refuse to give written informed consent
  • Patients who require general anesthesia
  • Patients who had previous uterine surgery or more than one previous Cesarean delivery
  • Patients with any condition predisposing to uterine atony and postpartum hemorrhage, such as abnormal placentation, multiple gestation, preeclampsia, macrosomia, polyhydramnios, uterine fibroids, bleeding diathesis, chorioamnionitis, or a previous history of postpartum bleeding
  • Emergency Cesarean section in labor
  • Patients on medications that could affect myometrial contractility, such as nifedipine, labetolol or magnesium sulphate.

Sites / Locations

  • Mount Sinai HospitalRecruiting

Arms of the Study

Arm 1

Arm 2

Arm 3

Arm 4

Arm 5

Arm 6

Arm 7

Arm 8

Arm Type

No Intervention

Active Comparator

Active Comparator

Active Comparator

Active Comparator

Active Comparator

Active Comparator

Active Comparator

Arm Label

Control (no oxytocin) + No recovery

Continuous oxytocin + No recovery

Continuous oxytocin + 30 minute recovery

Continuous oxytocin + 60 minute recovery

Control (no oxytocin) + No recovery + 10-7 oxytocin

Continuous oxytocin + No recovery + 10-7 oxytocin

Continuous oxytocin + 30 minute recovery + 10-7 oxytocin

Continuous oxytocin + 60 minute recovery + 10-7 oxytocin

Arm Description

A control experiment will be undertaken in which the myometrial explants will be exposed to PSS for 2-hours without any oxytocin. No recovery time.

10-5M oxytocin for 2 hours. No recovery time.

10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 30 minutes.

10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 60 minutes.

A second control experiment will be undertaken in which the myometrial explants will be exposed to PSS for 2-hours without any oxytocin. After 2 hours, the solution will be drained from the organ baths, and replaced with fresh PSS. Following this, the strip will be exposed to 10-7 oxytocin for 10 minutes.

10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to 10-7 oxytocin for 10 minutes.

10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 30 minutes. The strip will then be exposed to 10-7 oxytocin for 10 minutes.

10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 60 minutes. The strip will then be exposed to 10-7 oxytocin for 10 minutes.

Outcomes

Primary Outcome Measures

Oxytocin receptor (OTR) protein expression and localization
Western blotting will be performed to detect expression levels of the OTR protein and its localization within the plasma membrane, cytoplasmic or nuclear cell fractions.

Secondary Outcome Measures

Oxytocin receptor (OTR) phosphorylation patterns
Proximity assays will be used to detect OTR phosphorylation patterns, by looking at the extent of OTR-β-arrestin binding.
Protein expression levels of PLC, MEK5 and ERK5
Western blotting will be performed to detect protein expression levels of PLC, MEK5 and ERK5

Full Information

First Posted
May 3, 2016
Last Updated
October 24, 2022
Sponsor
Samuel Lunenfeld Research Institute, Mount Sinai Hospital
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1. Study Identification

Unique Protocol Identification Number
NCT02762669
Brief Title
Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization: an In-vitro Analysis of Oxytocin Receptor Expression and Signaling
Official Title
Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization: an In-vitro Analysis of Oxytocin Receptor Expression and Signaling
Study Type
Interventional

2. Study Status

Record Verification Date
October 2022
Overall Recruitment Status
Recruiting
Study Start Date
August 3, 2016 (Actual)
Primary Completion Date
December 2023 (Anticipated)
Study Completion Date
December 2023 (Anticipated)

3. Sponsor/Collaborators

Responsible Party, by Official Title
Sponsor
Name of the Sponsor
Samuel Lunenfeld Research Institute, Mount Sinai Hospital

4. Oversight

Data Monitoring Committee
No

5. Study Description

Brief Summary
Postpartum hemorrhage (PPH) is a leading cause of maternal mortality and morbidity worldwide, and is caused most commonly by poor uterine muscle contraction after delivery of the baby and placenta. The first line agent used in the prevention and treatment of PPH is oxytocin, which acts by binding with the oxytocin receptor (OTR) found on myometrial cells to cause uterine contraction. Oxytocin is also used for the augmentation of labor when spontaneous labor has been deemed ineffective. It is administered intravenously at progressively higher doses, until effective contractions are achieved and vaginal delivery results. However, if augmentation is determined to have failed, a Cesarean delivery (CD) is performed. One of the potential problems with oxytocin use during delivery is that it loses its effectiveness if the uterus has previously been pre-exposed to its high doses and/or for a prolonged duration during labor. This phenomenon is termed OTR desensitization, and can result in the attenuation of myometrial contractility induced by subsequent oxytocin administration, as well as PPH due to poor uterine tone. Furthermore, oxytocin can produce potentially fatal maternal hemodynamic adverse effects when administered at high doses, so it is advantageous to be able to use as low a dose as possible to obtain good uterine muscle tone. The objective of this study is to get a better understanding of the signaling pathways governing desensitization, resensitization and contractility in pregnant human myometrium. The investigators wish to investigate the effects of increasing recovery period on the expression patterns of the OTR and its signaling pathways in desensitized pregnant human myometrium. This study will help shed light on the molecular mechanisms responsible for desensitization and oxytocin-induced myometrial contractility, and will provide some insight into potential therapeutic targets to reduce the incidence of PPH and complications associated with using increasing concentrations of oxytocin. The hypothesis is that the expression and phosphorylation patterns of the OTR and downstream proteins will be altered in desensitized myometrium, and that these patterns will change with increasing rest periods and re-exposure to oxytocin.
Detailed Description
Clinically, women who require augmentation of labor are at increased risk of PPH due to their greater exposure to oxytocin in both duration and dose through exogenous administration, presumably mediated by OTR desensitization. In current practice, upon diagnosis of failure to progress during labor augmentation, oxytocin administration is discontinued, and as long as there is no indication for immediate delivery, there is a variable duration to proceed to CD. Due to the high likelihood of OTR desensitization in this patient population, it would be clinically relevant to determine the molecular mechanisms underlying this action. A recent study from the investigators' group, looking at the rest time required for recovery and resensitization of the OTR following desensitization, showed that there were no improvements in oxytocin-induced myometrial contractility after either a 30, 60 or 90 minute rest period. The reason for why resensitization does not occur remains unknown, but a possible explanation is that the OTRs undergo structural and functional changes during desensitization that prohibit their recovery. The investigators propose to use our previously established in-vitro model of labour augmentation and OTR desensitization (using pregnant human myometrium and an isometric tension recording device) to investigate the molecular mechanisms governing OTR desensitization and resensitization after stopping administration of oxytocin. Investigation of the signaling pathways responsible for these processes, as well as for oxytocin-induced contractions in a controlled in-vitro system will aid in the understanding of the kinetics of the OTR-oxytocin system and provide insight into potential pharmacotherapeutic targets to reduce the incidence of PPH.

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
Postpartum Hemorrhage
Keywords
Uterine contraction, Oxytocin desensitization

7. Study Design

Primary Purpose
Treatment
Study Phase
Not Applicable
Interventional Study Model
Parallel Assignment
Masking
None (Open Label)
Allocation
Non-Randomized
Enrollment
16 (Anticipated)

8. Arms, Groups, and Interventions

Arm Title
Control (no oxytocin) + No recovery
Arm Type
No Intervention
Arm Description
A control experiment will be undertaken in which the myometrial explants will be exposed to PSS for 2-hours without any oxytocin. No recovery time.
Arm Title
Continuous oxytocin + No recovery
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. No recovery time.
Arm Title
Continuous oxytocin + 30 minute recovery
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 30 minutes.
Arm Title
Continuous oxytocin + 60 minute recovery
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 60 minutes.
Arm Title
Control (no oxytocin) + No recovery + 10-7 oxytocin
Arm Type
Active Comparator
Arm Description
A second control experiment will be undertaken in which the myometrial explants will be exposed to PSS for 2-hours without any oxytocin. After 2 hours, the solution will be drained from the organ baths, and replaced with fresh PSS. Following this, the strip will be exposed to 10-7 oxytocin for 10 minutes.
Arm Title
Continuous oxytocin + No recovery + 10-7 oxytocin
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to 10-7 oxytocin for 10 minutes.
Arm Title
Continuous oxytocin + 30 minute recovery + 10-7 oxytocin
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 30 minutes. The strip will then be exposed to 10-7 oxytocin for 10 minutes.
Arm Title
Continuous oxytocin + 60 minute recovery + 10-7 oxytocin
Arm Type
Active Comparator
Arm Description
10-5M oxytocin for 2 hours. After 2 hours, the solution will be drained from the organ baths, and any residual solution will be removed by washing three times with PSS. Following this, the strip will be exposed to PSS for 60 minutes. The strip will then be exposed to 10-7 oxytocin for 10 minutes.
Intervention Type
Drug
Intervention Name(s)
Oxytocin
Other Intervention Name(s)
pitocin
Intervention Description
Oxytocin, 10-7mol/L to 10-5mol/L
Primary Outcome Measure Information:
Title
Oxytocin receptor (OTR) protein expression and localization
Description
Western blotting will be performed to detect expression levels of the OTR protein and its localization within the plasma membrane, cytoplasmic or nuclear cell fractions.
Time Frame
24 hours
Secondary Outcome Measure Information:
Title
Oxytocin receptor (OTR) phosphorylation patterns
Description
Proximity assays will be used to detect OTR phosphorylation patterns, by looking at the extent of OTR-β-arrestin binding.
Time Frame
24 hours
Title
Protein expression levels of PLC, MEK5 and ERK5
Description
Western blotting will be performed to detect protein expression levels of PLC, MEK5 and ERK5
Time Frame
24 hours

10. Eligibility

Sex
Female
Minimum Age & Unit of Time
16 Years
Maximum Age & Unit of Time
40 Years
Accepts Healthy Volunteers
Accepts Healthy Volunteers
Eligibility Criteria
Inclusion Criteria: Patients who give written consent to participate in this study Patients with gestational age 37-41 weeks Non-laboring patients, not exposed to exogenous oxytocin Patients requiring primary Cesarean delivery or first repeat Cesarean delivery Exclusion Criteria: Patients who refuse to give written informed consent Patients who require general anesthesia Patients who had previous uterine surgery or more than one previous Cesarean delivery Patients with any condition predisposing to uterine atony and postpartum hemorrhage, such as abnormal placentation, multiple gestation, preeclampsia, macrosomia, polyhydramnios, uterine fibroids, bleeding diathesis, chorioamnionitis, or a previous history of postpartum bleeding Emergency Cesarean section in labor Patients on medications that could affect myometrial contractility, such as nifedipine, labetolol or magnesium sulphate.
Central Contact Person:
First Name & Middle Initial & Last Name or Official Title & Degree
Mrinalini Balki, MD
Phone
416-586-4800
Ext
5270
Email
mrinalini.balki@uhn.ca
Overall Study Officials:
First Name & Middle Initial & Last Name & Degree
Mrinalini Balki, MD
Organizational Affiliation
MOUNT SINAI HOSPITAL
Official's Role
Principal Investigator
Facility Information:
Facility Name
Mount Sinai Hospital
City
Toronto
State/Province
Ontario
ZIP/Postal Code
M5G1X5
Country
Canada
Individual Site Status
Recruiting
Facility Contact:
First Name & Middle Initial & Last Name & Degree
Mrinalini Balki, MD
Phone
416-586-4800
Ext
5270
Email
mrinalini.balki@uhn.ca
First Name & Middle Initial & Last Name & Degree
John Kingdom, MD
First Name & Middle Initial & Last Name & Degree
Alice Luca, MSc
First Name & Middle Initial & Last Name & Degree
Dora Baczyk, MD

12. IPD Sharing Statement

Plan to Share IPD
No

Learn more about this trial

Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization: an In-vitro Analysis of Oxytocin Receptor Expression and Signaling

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