Prostaglandin pathways in equine myometrium regulations: endometrosis progression.

INTRODUCTION

Prostaglandins (PG) are important regulators of the myometrial contractility in mammals. Endometrosis, a condition characterized by morphological changes in the equine endometrium, also affects endometrial secretory function. However, it remains unclear whether and how endometrosis affects myometrial function.

METHODS

This study investigated: (i) mRNA transcription of genes encoding specific enzymes responsible for PG synthesis, such as prostaglandin-endoperoxide synthase (), PGE synthase (), PGF synthase () and : PGE receptors (), and PGF receptor () in equine myometrium and, (ii) the effects of PGE and PGF on myometrial contractile activity, during endometrosis in mares. The myometria used in experiments 1 and 2 were collected from mares in the mid-luteal ( = 23) and follicular ( = 20) phases of the estrous cycle, according to the histological classification of the endometrium (Kenney and Doig categories I, IIA, IIB, and III).

RESULTS

In experiment 1, changes in mRNA transcription of or in the myometrium during the course of endometrosis were determined using qPCR. During the mid-luteal phase, myometrial mRNA transcription of increased in mares with endometrial category IIB compared to category I. However, myometrial mRNA transcription of decreased during the progression of endometrosis compared to category I. During the follicular phase, mRNA transcription of and increased in mares with endometrial categories III or IIA, respectively. In addition, mRNA transcription of increased in mares with endometrium category IIA compared to category I. In experiment 2, the force of myometrial contractions was measured using an isometric concentration transducer. In the follicular phase, PGE decreased the force of contractions in mares with endometrial categories IIA, IIB, and III compared to the respective control groups. Prostaglandin F increased the force of myometrial contractions in mares with category IIA endometrium, whereas it decreased in category IIB compared to the respective control groups.

DISCUSSION

We concluded that in the progression of endometrosis there are changes in the myometrial transcription of mRNA encoding and , particularly and . Mares with endometrosis had abnormal myometrial contractile responses to PG. These findings suggest that myometrial function may be compromised during the progression of endometrosis.