@article{oai:niigata-u.repo.nii.ac.jp:00028392,
 author = {Takano, Hiroko and Niimura, Sueo},
 issue = {1},
 journal = {新潟大学農学部研究報告, 新潟大学農学部研究報告},
 month = {Sep},
 note = {We previously reported in porcine oocytes that the activities of some hydroxysteroid dehydrogenases (HSDs) and the size of lipid droplets in the cytoplasm decreased as nuclear maturation progressed, and that the progression of nuclear maturation, the decrease of HSD activities and the reduction in the size of lipid droplets did not occur in those treated with olomoucine. From these results, we suggested that the changes in the steroid metabolism and the size of lipid droplets in the cytoplasm were closely associated with nuclear maturation. However, whether olomoucine directly acts on the cytoplasm to inhibit such changes could not be determined. In the present investigation, the activities of some HSDs and Sudanophilic lipid droplets were histochemically demonstrated in porcine oocytes in which the nuclear maturation was suppressed and the high cAMP level in the cytoplasm was maintained by the treatment of IBMX or dbcAMP, in order to clarify the relationship between nuclear maturation and the metabolism of steroids and the number of lipid droplets in the cytoplasm. Of the oocytes cultured with IBMX or dbcAMP for 22 hrs, 97 and 100% were in the germinal vesicle (GV) stage, respectively. The percentages of oocytes in the GV stage were significantly higher in both the treated oocytes than in control oocytes. The rates of the treated oocytes showing the activities of Δ^<5>-3β-HSD (using pregnenolone and 17α-hydroxypregnenolone as the substrates), 17β-HSD (estradiol-17β), 20α-HSD (20α-hydroxyprogesterone) and 20β-HSD (17β-hydroxyprogesterone) did not differ from those of control oocytes. Also, there were no differences in the number of lipid droplets of different sizes between IBMX- or dbcAMP-treated oocytes and control oocytes. From these findings, it was suggested that the changes in the steroid metabolism and the size of lipid droplets in the cytoplasm with oocyte maturation depend on the cAMP level in their cytoplasm rather than the progression of nuclear maturation., 我々は、ブタ卵母細胞において、核の成熟に伴って細胞質ではいくつかのステロイドの代謝低下と脂質小滴の小型化が起こることを以前報告した。また、核の成熟をオロモウシンで処置して阻止した卵母細胞では、ステロイド代謝の低下および脂質小滴の小型化はみられなかったことから、細胞質でのこれらの変化は核の成熟と密接に関係していることを推察して報告した。しかし、オロモウシンがステロイド代謝の低下および脂質小滴の小型化に直接関係しているのか否かは明らかにできなかった。そこで、オロモウシンとは異なった機構、すなわち細胞質のcAMPレベルを高く維持することによって核の成熟を抑制する作用のあるIBMXとdbcAMPを用いて、ブタの卵母細胞を処置し、ステロイド代謝と脂質小滴の数を組織化学的に観察した。IBMXあるいはdbcAMPで22時間処置した卵母細胞において、核は97および100％で卵核胞期にあり、これらの処置により成熟分裂の再開が抑制されていることが確認された。一方、IBMX あるいはdbcAMPで22時間処置した卵母細胞において、Δ^<5>-3β-HSD活性（基質としてpregnenoloneと17α-hydroxypregnenolone を使用）、17β-HSD 活性（estradiol-17β）、20α-HSD 活性（20α-hydroxyprogesterone）および20β-HSD活性（17β-hydroxyprogesterone）を有するものの割合、ならびに各種大きさの脂質小滴の数は、どちらも対照の卵母細胞におけるそれらと相違なかった。以上の結果から、細胞質におけるステロイド代謝の低下および脂質小滴の小型化は、核の成熟の進行よりも、細胞質のcAMP の量に依存して起こることが推察された。},
 pages = {27--33},
 title = {Nuclear Maturation, Steroid Metabolism and Lipid Droplets in Porcine Oocytes Cultured with IBMX or dbcAMP},
 volume = {61},
 year = {2008}
}