# Bacterial endotoxin does not increase sensitivity to oxytocin and prostaglandin F2a of the myometrium from bilaterally ovariectomized rats

Rafael Garcia Villar, D J Dipiazza, Peter W Nathanielsz

► To cite this version:

Rafael Garcia Villar, D J Dipiazza, Peter W Nathanielsz. Bacterial endotoxin does not increase sensitivity to oxytocin and prostaglandin F2a of the myometrium from bilaterally ovariectomized rats. 41st Annual Scientific Meeting of the Society for Gynecologic Investigation of the, Mar 1994, Chicago, Illinois, United States. **hal-01606200**

HAL Id: hal-01606200

https://hal.science/hal-01606200

Submitted on 7 Jun 2020

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>
SOCIETY FOR GYNECOLOGIC INVESTIGATION
ABSTRACT FORM

Office Use Only:
ID# __________ Abst# __________
Date Rec'd __________

48th Annual Meeting
CHICAGO, ILLINOIS

Abstract # 0.196

DO NOT FOLD ABSTRACT FORM

BACTERIAL ENDOTOXIN (ENDO) DOES NOT INCREASE SENSITIVITY TO OXYTOCIN (OT) AND PROSTAGLANDIN (PG) F<sub>2α</sub> (PGF<sub>2α</sub>) OF MYOMETRIUM (MYO) FROM BILATERALLY OVARIECTOMIZED (BOVX) RATS. DiPiazza,D.J.*, Garcia-Villar,R.* and Nathanielsz,P.W. Laboratory for Pregnancy and Newborn Research, Dept. Physiology., Cornell University, Ithaca, NY 14853. HD 21350.

Previous studies have established a link between bacterial infections and premature labor. Experimental endotoxemia induces premature labor in animals. Current hypotheses of infection-stimulated premature labor implicate increased cytokine and PG synthesis. No data exist on myometrial sensitivity changes to uterotonic agonists following ENDO. We investigated the effect on in vitro myometrial contractility of *E. coli* lipopolysaccharide administered to BOVX rats. **METHODS:** Virgin female CD rats (200-250 gm) were given a single intraperitoneal dose of LPS (0.5 mg) 7-12 days following BOVX. Rats were euthanized with CO<sub>2</sub> 17h following ENDO. Full thickness strips of uteri were suspended in a longitudinal direction at one gram tension. Concentration response curves (CRC) were obtained to PGF<sub>2α</sub> and OT (Fig.1). OT and PGF<sub>2α</sub> sensitivity were determined from EC50 (concentration inducing 50% max response).

**RESULTS:** Leukopenia confirmed that ENDO injection caused an immune response. LPS had no effect on spontaneous contractility, OT or PGF<sub>2α</sub> sensitivity of MYO from LPS-treated rats (n = 5) compared with controls (n = 5). EC50 to OT was 0.33 nM and 0.44 nM and to PGF<sub>2α</sub> was 36.8 nM and 37.4 nM in LPS treated and controls respectively.

**CONCLUSIONS:** ENDO does not increase MYO sensitivity to OT or PGF<sub>2α</sub> in BOVX rats. Increased myometrial activity in premature labor may not be due to increased MYO receptor affinity for OT or PG but rather increased production of uterotonins or alteration of post-receptor events. Further studies are required to elucidate the ability of steroids present in pregnancy or mechanotransduction due to stretch to modify the effect of ENDO.

<figure><img src="image_2.png" /><figcaption>Fig. 1 CRC (mean ± SEM) to OT of MYO from both LPS-treated (n=5) (■--■) and saline-treated (n-5) (□--□) BOVX.</figcaption></figure>

ABSTRACT MUST BE RECEIVED BY CLOSE OF BUSINESS (5:00 PM), FRIDAY, OCT. 8, 1993.

Mail to:

Ms. Laurie Daniels
The American Board of
Ob-Gyn
2915 Vine Street
Dallas, TX 75204

Select the section that should review this abstract (check one)

<figure><img src="image_3.png" /></figure>

Basic Endocrinology

<figure><img src="image_4.png" /></figure>

Infections

<figure><img src="image_5.png" /></figure>

Clinical Endocrinology

<figure><img src="image_6.png" /></figure>

Contraception

<figure><img src="image_7.png" /></figure>

Basic Perinatology

<figure><img src="image_8.png" /></figure>

Epidemiology

<figure><img src="image_9.png" /></figure>

Clinical Perinatology

<figure><img src="image_10.png" /></figure>

Gynecology

<figure><img src="image_11.png" /></figure>

Genetics

<figure><img src="image_12.png" /></figure>

Other

<figure><img src="image_13.png" /></figure>

Immunology

<figure><img src="image_14.png" /></figure>

Oncology

Presentation Preferred:

<figure><img src="image_15.png" /></figure>

Slide Presentation

<figure><img src="image_16.png" /></figure>

Poster Presentation

<figure><img src="image_17.png" /></figure>

No Preference,
Slide vs. Poster

Withdrawal may be made
only for sufficient cause in
writing.

Session Preferred:

Code Number/Category

1. 32

Infection

2. 60-Uterine

Contractility

3. 43

Parturition

☐ Check here if the first author is a research fellow funded by Institution such as NIH, AGOS, ACOG, etc.

Name of sponsoring organization

**IMPORTANT:** Be sure to stay within border. See sample abstracts, typing, and mailing instructions on the reverse side of this form. Use enclosed check list for abstract preparation. The original typed copy of this abstract form (for reproduction by photo-offset in the 1993 Annual Program of the Society for Gynecologic Investigation) must be submitted, together with two photocopies of the abstract form and ten (10) additional double-spaced copies on plain 8 1/2" X 11" paper. For additional copies, include title, but omit name(s) of author(s) and identifying institution(s). All material must reach Laurie Daniels NO LATER THAN THE CLOSE OF BUSINESS (5:00 P.M.), FRIDAY, OCTOBER 8, 1993. Use air mail or express mail from overseas.

Mailing address of first author (Please print or type)

David J. PiPiazza
Laboratory for Pregnancy and Newborn
Research
College of Vet. Med., Dept. Physiol.
815 VRT
Cornell University,
Ithaca, NY 14853-6401

Telephone No. (607) 253-3082

Each abstract form submitted MUST BE SIGNED by a member of The Society for Gynecologic Investigation. As a member of the SGI, I assume full responsibility for the quality of this material and its presentation, if selected. I also assume the $30 penalty fee for retyping and/or corrections as charged by the Program Committee. **In addition, this material will not be published, or presented at a national meeting, prior to its presentation at the SGI, if accepted.**

(Member's Name) Peter W. Nathanielsz, MD, PhD, ScD

(Member's Signature)

<figure><img src="image_18.png" /></figure>

(Member's Phone No.) (607) 253-3082

<figure><img src="image_19.png" /></figure>