Effect of progesterone on in vitro meiotic maturation of canine oocytes associated with Cx37 and Cx43 gene expression

Monica De Los Reyes; Jaime Palomino; Allison Villagra; George Ramirez; Oscar A Peralta; Victor H Parraguez; Karla Aspee

doi:10.1016/j.theriogenology.2023.04.005

Effect of progesterone on in vitro meiotic maturation of canine oocytes associated with Cx37 and Cx43 gene expression

Theriogenology. 2023 Jul 1:204:50-57. doi: 10.1016/j.theriogenology.2023.04.005. Epub 2023 Apr 10.

Authors

Monica De Los Reyes¹, Jaime Palomino², Allison Villagra³, George Ramirez³, Oscar A Peralta³, Victor H Parraguez⁴, Karla Aspee³

Affiliations

¹ Laboratory of Animal Reproduction, Faculty of Veterinary Sciences, University of Chile, Santiago, Chile. Electronic address: mdlreyes@uchile.cl.
² Laboratory of Animal Reproduction, Faculty of Veterinary Sciences, University of Chile, Santiago, Chile; College of Veterinary Medicine, Bernardo O'Higgins University, Santiago, Chile.
³ Laboratory of Animal Reproduction, Faculty of Veterinary Sciences, University of Chile, Santiago, Chile.
⁴ Laboratory of Animal Physiology, Faculty of Veterinary Sciences, University of Chile, Santiago, Chile.

PMID: 37068395
DOI: 10.1016/j.theriogenology.2023.04.005

Abstract

Progesterone (P4) concentrations in canines are exceptionally high in the periovulatory period. However, the mechanisms by which P4 modulates final oocyte development in dogs remain to be characterized. The aim of this study was to evaluate the effect of P4 on meiotic development related to the gene expression of connexin 37 (Cx37) and connexin 43 (Cx43) in the canine cumlus oocyte complexes (COCs). COCs were isolated from 120 canine ovaries after a routine ovariohysterectomy. In each experiment, groups of COCs retrieved from the antral follicles were subjected to in vitro maturation (IVM) for 72 h without (control) or with P4 (50 μg/mL and 100 μg/mL) or the P4 receptor antagonist, aglepristone (RU534 at 1 μM and 10 μM). Some of the COCs recovered (from each group) after 72 h of IVM were subjected to meiotic evaluation; the remaining COCs, and those not subjected to IVM, were used to analyze the gene expression of Cx37 and Cx43 by qPCR. The results were evaluated using ANOVA. The addition of P4 increased (P < 0.05) the meiotic development compared to that in the control or aglepristone groups. The highest (P < 0.05) percentage of oocytes in the MII stage was observed upon P4 supplementation. In contrast, the highest percentage (P < 0.05) of oocytes arrested in the GV stage and the lowest (P < 0.05) percentages in the MII stage were observed for COCs cultured with aglepristone. Although a significant decrease in the mRNA levels of both connexins was observed after culturing, no effect on Cx37 and Cx43 gene expression was observed when exogenous P4 was added compared to those of the control group. However, COCs cultured with aglepristone exhibited higher (P < 0.05) expression of Cx37 and Cx43 than COCs in the control IVM-group, regardless of the concentration. In conclusion, our results suggest that a high dosage of P4 during IVM enhances the nuclear maturation of canine oocytes without altering the gene expression levels of Cx37 and Cx43. However, the increase in their expression upon treatment with a P4 antagonist indicates an in vivo role for this hormone in the endogenous modulation of both Cx37 and Cx43.

Keywords: Aglepristone; Cumulus-oocyte complexes; Dog; Gap junction; mRNA; steroid.

MeSH terms

Animals
Connexin 43* / metabolism
Connexins / metabolism
Cumulus Cells / metabolism
Dogs
Female
Gap Junction alpha-4 Protein
Gene Expression
In Vitro Oocyte Maturation Techniques / veterinary
Oocytes
Progesterone* / pharmacology

Substances

Progesterone
Connexin 43
Connexins