포유동물 난자-난구 복합체의 Metabolic cooperativity

Studies on the Metabolic Cooperativity between Ooccte and Cumulus Cells in Mammalian Oocyte Cumulus Complexes in vitro

생쥐혹은 돼지의 난자-난구 복합체를 인공배양하면서 뇌하수체호르몬 혹은 세포내 cAMP의 농도를 높이는 시약을 사용하여 난자의 성숙과 난구세포의 분산을 조절하고 이 때 두 세토들 사이에 상호협력(metabolic cooperativity)관계가 어떻게 변하는지를 조사하여 보았다. 생귀와 돼지의 난구세포들은 뇌하수체호르몬이나 cAMP의 증가에 의해 분산이 유도됨과 동시에 배양액 내에서 있는 uridine의 흡수가 크게 촉진되었다. (대조군의 약 4배). 그러나 난구세포에 흡수된 uridine이 난자로 전달되는 물질이동율(transfer ratio)은 대조군과 같이 시간이 지남에 따라 감소하였으며 cAMP의 영향도 거의 받지 않았다. 또한 물질이동율의 감소는 난구세포의 부산여부나 난자의 성숙(핵붕괴) 여부에 크게 영향을 받지 않았다.단지 생쥐의 경우 호르몬에 의해 물질이동율의 감소가 더욱 두드러지게 나타나는 경우를 볼수 있었다. 따라서 물질이동율의 변화가 난구세포의 분산이나 난자의 성숙과 직접 관련이 없는 것으로 보여지며 두 세포들 사이의 metabolic cooperativity가 난자의 성숙조절에 중요한 요인이 되지 않는다는 것을 알았다.

The relationship between cumulus cell expansion, cocyte maturation and metabolic cooperativitiy was investigated by using mouse and pig cocyte-cumulus complexes in vitro. Cocyte germinal vesicle breakdown (GVBD) and cumulus expansion were manipulated with hormones or reagents which increase intracellular cAMP leveL Metabolic cooperativity between oocyte and cumulus cells was assessed by determination of the fraction of radiolabelled uridine marker that was transferred from the cumulus mass to the oocyte. Uptake of uddine marker by mouse and pig cumulus mass was increased by about fourfold of basal level with the stimulation of hormones (human choriononic gonadotrophin, HCG; follicle stimulating hormone, FSH) or cyclic AMP sttmulators (3-isobutyl-1-methylxanthine, IBMX; forskolin) during culture. However, the fraction of uridine that was transferred from the cumulus mass to the cocyte (transfer ratio) was gradually decreased during culture, irrespective with the presence of hormones or stimulators. The decrease of the transfer ratio was not correlated with the state of occyte whether they have GV or not, or with the degree of cumulus expansion. In mouse complexes, HCG induced more significant reducton of transfer ratio than other treatments. These results do not support the idea that modulations of metabolic cooperativity between cumulus cells and oocytes are important for the regulation of meiotic resumption in mammals.