Acetylcholine controls mouse oocyte maturation via downregulation of cAMP

摘要

1. In mice, acetylcholine (ACh) plays an important role in oocyte activation and embryonic development. However, the role of ACh in mouse oocyte maturation has not been investigated. 2. Inthepresent study,theeffectsof 100 umol/Land 1 mmol/L ACh on maturation processes of murine germinal vesicle (GV) intact oocytes (GV oocytes) exposed to 10 and 100 umol/L 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of cyclic nucleotide phosphodiesterase, were evaluated morphologically and immunologically. It has been shown that IBMX inhibits the resumption of meiosis by preventing cAMP breakdown. 3. In the present study, at the start of in vitro culture 100% of oocytes were at the GV stage. After 18 h culture, 95 +- 3, 0 and 85.8 +- 10.2% of oocytes had passed the GV stage in the control, IBMX and IBMX + ACh groups,respectively.The IBMX-induced inhibition of the maturation process was significantly attenuated by approximately 90% by ACh in groups treated with 10 umol/L IBMX + 100 umol/L ACh and 100 umol/L IBMX + 1 mmol/L ACh. Although cAMP levels were high in oocytes treated with 100 umol/L IBMX, levels were reduced in groups treated simultaneously with 100 umol/L ACh. Furthermore, compared with mature oocytes, ACh-treated GV oocytes exhibitedsignificantly lower (byapproximately 2.3-fold)or absent Ca~(2+) peaks. 4. The results of the present study indicate that maturation of GV oocytes, arrested by IBMX treatment, is resumed following ACh treatment and that this effect is due to downregulation of cAMP rather than changes in intracellular Ca~(2+) levels.