Ion currents modulating oocyte maturation in animals

Abstract

Growing oocytes are arrested at the first prophase of meiosis which is morphologically identified by the presence of a large and vesicular nucleus, called the germinal vesicle. The dissolution of the germinal vesicle marks the resumption of meiosis during which the oocyte undergoes massive modifications up to the second meiotic block, which is removed at fertilization. The interval between the first and the second meiotic block is defined as maturation and the events occurring during this period are crucial for ovulation, fertilization, and embryo development. Oocytes are excitable cells that react to stimuli by modifying their electrical properties as a consequence of ion currents flowing through ion channels on the plasma membrane. These electrical changes have been largely described at fertilization whereas little information is available during oocyte maturation. The aim of this review is to give an overview on the involvement of ion channels and ion currents during oocyte maturation in species from invertebrates to mammals. The results summarized here point to the possible functional role of ion channels underlying oocyte growth and maturation.

An insufficient increase of cytosolic free calcium level results postovulatory aging-induced abortive spontaneous egg activation in rat

“…Data of the present study suggest that the extracellular Ca 2+ increased rate of abortive SEA during initial period (3 and 5 h) of in vitro culture, while all eggs underwent abortive SEA if cultured for 7 h either in Ca -induced abortive SEA. These data suggest that the L-type Ca 2+ channels are still operated in ovulated eggs [37] and nifedipine blocks L-type Ca 2+ channels and inhibits abortive SEA in rat eggs [29]. These data together with previous findings suggest that postovulatory aging induces abortive SEA probably by increasing cytosolic free Ca 2+ level.…”

Expression of G protein estrogen receptor (GPER) on membrane of mouse oocytes during maturation

“…It has been shown that estrogen plays a key role in oocytes maturation in mammalian models by inducing a series of cellular signaling including inositol triphosphate (IP3) and ryanodine (Ry)-mediated intracellular free calcium concentration ([Ca 2+ ]i) [23][24][25][26] and calcium signaling [27]. The development of the ability of oocytes to release Ca 2+ in response to the fertilizing spermatozoa is an essential step during oocyte maturation [28].…”

Efecto De La Aplicación De Gonadotropinas Recombinantes Humanas Sobre La Producción Y Calidad De Ovocitos Y Embriones en Coneja

“…En aquellos ovocitos listos para madurar, durante las primeras horas de la maduración ovocitaria, tras la unión de la hormona LH con sus receptores, presentes en las células murales de la granulosa (Mehlmann, 2005;Sirard et al, 2006;, las células del cúmulo juegan un papel fundamental (Merton et al, 2003), ya que es en las 12 primeras horas tras el pico de LH cuando se produce la disrupción de las uniones entre las células del cúmulo y el ovocito (Tosti, 2006), así como su expansión y modificación . De hecho, la reanudación de la meiosis podría estar inducida por la generación de señales que se transfieren al ovocito, por la pérdida de contacto entre el ovocito y el ambiente folicular o por ambas (Tosti, 2006).…”

“…De hecho, la reanudación de la meiosis podría estar inducida por la generación de señales que se transfieren al ovocito, por la pérdida de contacto entre el ovocito y el ambiente folicular o por ambas (Tosti, 2006).…”

“…Otro orgánulo cuyos cambios estructurales y bioquímicos durante la ovogénesis son críticos, es el retículo endoplasmático (RE), involucrado en el almacenamiento y liberación del Ca, proceso extremadamente importante en las señales intracelulares , que tiene una implicación directa en la reanudación de la meiosis y en la evolución de la misma (Tosti, 2006).…”