Title: GnRH-induced maturation of rat oocytes: a calcium-dependent process.

POPLINE Document Number: 075740

Author(s):

Goren S
Oron Y
Dekel N

Source citation:

In: Growth factors in fertility regulation. Proceedings of the Symposium on Potential of Molecular Biology in Fertility Regulation: Growth Regulatory Factors, jointly sponsored by the World Health Organization and the National Institute of Child Health and Human Development and held at the National Institutes of Health, Bethesda, Maryland, on September 22-24, 1988, edited by Florence P. Haseltine, Jock K. Findlay. Cambridge, England, Cambridge University Press, 1991. :13-22. (Scientific Basis of Fertility Regulation)

Abstract:

This report describes studies of maturation of rat oocytes enclosed in their follicles in vitro. These follicles are held in mitotic arrest so the role of calcium and hormones in induction of maturation can be analyzed by the presence or absence of the germinal vesicle. Follicles were incubated with a GnRH agonist alone or with calcium-modulating agents for various time periods, then opened and observed for maturation. Oocytes normally undergo maturation within 2 hours in the presence of calcium, but when a calcium ionophore is added the process takes 6 hours. Elevated calcium levels enhanced maturation induced by GnRH analog. This calcium effect did not involve voltage-sensitive channels, since calcium channel blockers did not affect maturation. Maturation was elicited by A23187, suggesting a role for protein kinase C, but not by calmodulin, since an inhibitor of calmodulin did not affect maturation. The addition of dibutyryl cyclic AMP blocked calcium-induced maturation suggesting that the effect of cAMP is distal to that of calcium. There are receptors for GnRH on rat granulosa cells and oocytes as well, but their physiological role is still being studied. These studies suggest that calcium is involved in oocyte maturation induced by GnRH.

Keywords:

Research Report
Ovarian Effects
Adenosine Cyclic Monophosphate
Pituitary Hormone Releasing Hormones
Calcium
Hormone Receptors
Ovum
Clinical Research
Animals, Laboratory
In Vitro
Inorganic Chemicals
Ovary
Genitalia, Female
Genitalia
Urogenital System
Physiology
Biology
Hormones
Endocrine System
Metals
Vitamins and Minerals
Membrane Proteins
Germ Cells
Research Methodology
Ingredients and Chemicals