Ex Vivo Method for Assessing the Mouse Reproductive Tract Spontaneous Motility and a MATLAB-based Uterus Motion Tracking Algorithm for Data Analysis

Summary

Uterine contractions are important for the well-being of females. However, pathologically increased contractility may result in dysmenorrhea, especially in younger females. Here, we describe a simple ex vivo preparation allowing quick assessment of the efficacy of smooth muscle relaxants that may be used for treating dysmenorrhea.

Abstract

Dysmenorrhea, or painful cramping, is the most common symptom associated with menses in females and its severity can hinder women's everyday lives. Here, we present an easy and inexpensive method that would be instrumental for testing new drugs decreasing uterine contractility. This method utilizes the unique ability of the entire mouse reproductive tract to exhibit spontaneous motility when maintained ex vivo in a Petri dish containing oxygenated Krebs buffer. This spontaneous motility resembles the wave-like myometrial activity of the human uterus, referred to as endometrial waves. To demonstrate the effectiveness of the method, we employed a well-known uterine relaxant drug, epinephrine. We demonstrate that the spontaneous motility of the entire mouse reproductive tract can be quickly and reversibly inhibited by 1 µM epinephrine in this Petri dish model. Documenting the changes of uterine motility can be easily done using an ordinary smart phone or a sophisticated digital camera. We developed a MATLAB-based algorithm allowing motion tracking to quantify spontaneous uterine motility changes by measuring the rate of uterine horn movements. A major advantage of this ex vivo approach is that the reproductive tract remains intact throughout the entire experiment, preserving all intrinsic intrauterine cellular interactions. The major limitation of this approach is that up to 10-20% of uteri may exhibit no spontaneous motility. Thus far, this is the first quantitative ex vivo method for assessing spontaneous uterine motility in a Petri dish model.

Introduction

As a major female organ, the uterus is crucial for reproduction and essential for the nourishment of the fetus¹. The uterus consists of three layers: the perimetrium, myometrium and endometrium. The myometrium is the major contractile layer of the uterus and plays a key role in fetus delivery. The endometrium is the innermost layer lining the uterine cavity and is essential for embryo implantation. In non-pregnant females of reproductive age, the endometrial layer is shed monthly at the beginning of the menstrual cycle. The myometrium aids in this shedding process by maintaining the spontaneous myometrial contractions needed for clearing the ne....

Protocol

All procedures with animals have been approved by the Institutional Animal Care and Use Committee at the Indiana University School of Medicine (Indianapolis, IN). 2-5 month-old F2-129S-C57BL/6 sexually-mature female mice were used in the study.

CAUTION: Ensure safety by wearing a lab coat, mask, and gloves when working with animals and biohazardous materials.

1. Solution Preparation

1. Prepare the Krebs Buffer, which contains:  130 mM .......

Discussion

Here, we described a method for assessing spontaneous contractility of the entire rodent reproductive tract, which includes the ovaries, oviducts, uterine horns, and the vagina. We used a similar method to demonstrate the relaxant effect of phenylephrine on spontaneous uterine motility¹³, however, in the past we were unable to provide quantitative analysis of the data. In this work, we developed an algorithm for quantitative motility data analysis using the MATLAB motion tracking module. This is a.......

Materials

Name	Company	Catalog Number	Comments
Epinephrine hydrochloride	Sigma-Aldrich	E4642
Dulbecco's PBS	Fisher Sceintific	17-512Q
Ethanol 200 PROOF	Decon Laboratories	2701
NaCl	Sigma-Aldrich	S7653
Glucose	Sigma-Aldrich	G7528
KCl	Sigma-Aldrich	P9333
CaCl2 · 2H2O	Sigma-Aldrich	C5080
NaH2PO4	Sigma-Aldrich	S0751
MgCl2  · 6H2O	Sigma-Aldrich	M9272
NaHCO3	Sigma-Aldrich	S6297
Isoflurane, USP	Patterson Veterinary	07-893-2374
Dissecting Extra-Fine-Pointed Precision Splinter Forceps	Fisher Sceintific	13-812-42
Curved Hardened Fine Iris Scissors	Fine Science Tools	14091-09
Dissection High-performance Modular Stereomicroscope	Leica	MZ6
Digital 5 Megapixel Color Microscope Camera with active cooling system	Leica	DFC425 C
Stereomaster Microscope Fiber-Optic Light Sources	Fisher Sceintific	12-562-21
Weigh Boat	Fisher Sceintific	WB30304
Convertors Astound Standard Surgical Gown	Cardinal Health	9515	Small, Medium or Large
Gloves	McKesson Corporation	20-1080	Small, Medium, or Large; powder-free sterile latex or nitrile surgical gloves
Petri Dish	Corning Falcon	351029	100 mm
Petri Dish	Corning Falcon	353001	35 mm
95% O2- 5% CO2 gas mixture	Praxair	MM OXCD5-K
Ear-loop Masks	Valumax International	5430E-PP
DSLR 24.2 MP Camera	Canon	EOS Rebel T6i
MATLAB	MathWorks	N/A	version 2019 or later