Calcium elevation in sheep cumulus-oocyte complexes after luteinising hormone stimulation

被引:0
作者
Mattioli, M [1 ]
Gioia, L [1 ]
Barboni, B [1 ]
机构
[1] Univ Teramo, Fac Med Vet, Ist Fisiol Vet, I-64020 Nepezzano, TE, Italy
关键词
oocyte; cumulus cells; calcium; luteinising hormone (LH);
D O I
10.1002/(SICI)1098-2795(199807)50:3<361::AID-MRD13>3.0.CO;2-7
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
We investigated Ca2+ levels in intact cumulus-oocyte complexes (COCs) on exposure to peak levels of luteinising hormone (LH). Specific preparations were used where cumulus corona cells were loaded with a membrane-permeant Ca2+-sensitive dye (FLUO-3AM), whereas the oocyte was injected directly with the nonpermeant form of the dye (FLUO-3). After exposure to LH, cumulus and corona radiata cells showed distinct rises in intracellular Ca2+ in 50-200 sec. The pattern of Ca2+ response varied in the different cells both for the duration of the transients and for their persistence. Interestingly, Ca2+ elevations were recorded in all the layers of the cumulus mass, including the innermost layer of corona cells, demonstrating the wide diffusion of LH receptors. Following the Ca2+ raise in somatic cells, an intracellular Ca2+ elevation also was recorded within the oocyte with a delay of 100-300 sec. The elevation started at the cortex of the oocyte and then spread all over the ooplasm. The addition of verapamil or manganese chloride did not prevent LH-induced Ca2+ elevation in the COC, whereas mechanical uncoupling of cumulus cells from the oocyte prevented any Ca2+ response within the oocyte. The results indicate that cumulus-corona cells are capable of transducing LH message by rising intracellular Ca2+ and show that this signal is rapidly transferred into the oocyte through gap junctions. This may result from the direct diffusion of Ca2+ or its putative releaser IP3 from cumulus cells to the oocyte. (C) 1998 Wiley-Liss, Inc.
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页码:361 / 369
页数:9
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