Lithium inhibits amplification or action of the maturation-promoting factor (MPF) in meiotic maturation of starfish oocytes.
Microinjection of LiCl reversibly inhibits hormone-induced meiotic maturation of starfish oocytes. Microinjection of NaCl (even in ouabain-treated oocytes) or KCl, or external application of LiCl have no such effect. Blockade of meiotic maturation by Li+ occurs even when microinjection is performed after the hormone dependent period has ended, that is the period during which the hormone must be present in the medium in order that meiosis can take place. Li+ microinjection prevents oocytes from meiosis reinitiation following transfer of cytoplasm taken from maturing oocytes, which contain a maturation-promoting factor (MPF). Cytoplasm taken from Li+-injected and hormone-treated oocytes does not trigger meiosis reinitiation when transferred in control immature oocytes. Intracellular pH does not change following LiCl microinjection. Simultaneous microinjection of either K+, Na+, or EGTA does not prevent Li+-dependent inhibition in oocytes.
D000818:Animals; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D006133:Growth Substances / Q000378:metabolism*; D008094:Lithium / Q000494:pharmacology*; D016200:Maturation-Promoting Factor; D008540:Meiosis / Q000187:drug effects; D008845:Microinjections; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development*; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013215:Starfish
D006133:Growth Substances; D004533:Egtazic Acid; D008094:Lithium; D012964:Sodium; D016200:Maturation-Promoting Factor; D011188:Potassium