In vitro Activation of Mouse Oocytes through Intracellular Ca2+ Regulation

Nining Handayani; Budi Wiweko; Sarah Chairani Zakirah; Arief Boediono

doi:10.4103/jhrs.JHRS_122_19

In vitro Activation of Mouse Oocytes through Intracellular Ca2+ Regulation

J Hum Reprod Sci. 2020 Apr-Jun;13(2):138-144. doi: 10.4103/jhrs.JHRS_122_19. Epub 2020 Jul 9.

Authors

Nining Handayani¹, Budi Wiweko^{2

3

4}, Sarah Chairani Zakirah^{2

4}, Arief Boediono⁵

Affiliations

¹ Reproductive Science Master Program of Biomedical Science, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia.
² Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia.
³ Yasmin IVF Clinic, Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia.
⁴ Human Reproductive, Infertility, and Family Planning Research Center, Indonesian Medical Education and Research Institutes, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia.
⁵ Department of Anatomy, Physiology and Pharmacology, IPB University, Bogor, Indonesia.

Abstract

Background: Ca²⁺ signaling pathway is suggested to play an essential role in mediating oocyte maturation.

Aims: The aim of this study was to evaluate intracellular Ca²⁺ of resistant immature oocytes that failed to resume meiosis following subsequent in vitro culture reach metaphase II after calcium ionophore A23187 activation.

Settings and design: This in vitro analytical experimental study was conducted at Animal Science Laboratory of Indonesian Medical Education and Research Institute (IMERI), Human Reproductive Infertility and Family Planning of IMERI, and Electrophysiology Imaging of Terpadu Laboratory, Faculty of Medicine, University of Indonesia.

Methods: A total of 308 oocytes classed as resistant immature following in vitro culture were randomly allocated to control (n = 113) and treatment groups (n = 195). The oocyte activation group was exposed to A23187 solution for 15 min and then washed extensively. Maturation was evaluated by observing the first polar body extrusion 20‒24 h after A23187 exposure. Ca²⁺ imaging was conducted using a confocal laser scanning microscope to identify the dynamic of Ca²⁺ response.

Statistical analysis: SPSS 20, Chi-square, and Mann-Whitney U-test were used in this study.

Results: Activation of resistant immature oocytes with A23187 significantly increased the number of oocyte maturation compared with the control group (P < 0.001). Furthermore, fluorescent intensity measurements exhibited a significant increase in the germinal vesicle stage when activated (P = 0.005), as well as the metaphase I stage, even though differences were not significant (P = 0.146).

Conclusion: Artificial activation of resistant immature oocyte using chemical A23187/calcimycin was adequate to initiate meiosis progress.

Keywords: Artificial oocyte activation; Ca2+ signaling; calcimycin; calcium ionophore A23187; meiotic arrest.