Changes in the Activities of Hydroxysteroid Dehydrogenases in Porcine Oocytes during Meiotic Maturation In Vitro.

Abstract

Abstract. The activities of hydroxysteroid dehydrogenases (HSDs) were histochemically demonstrated in cultured porcine oocytes, and the changes in steroid metabolism during meiotic maturation and also the relationship between nuclear maturation and changes in steroid metabolism in the cytoplasm were examined. The activities of ∆ 5 -3β-HSD, 17β-HSD, 20α-HSD and 20β-HSD were observed in 91 to 97% of porcine oocytes soon after collection. The percentages of oocytes showing the activities of ∆ 5 -3β-HSD (using DHA as the substrate), 17β-HSD (testosterone) and 20β-HSD (20β-hydroxyprogesterone) did not change during maturation culture, while those showing the activities of ∆ 5 -3β-HSD (pregnenolone and 17α-hydroxypregnenolone), 17β-HSD (estradiol-17β), 20α-HSD (20α-hydroxyprogesterone) and 20β-HSD (17α-hydroxyprogesterone) decreased as the time of maturation culture was prolonged and reached 4, 0, 0, 2 and 0%, respectively, after 44 h culture. In the oocytes cultured for 22 h with olomoucine, nuclei were all in the germinal vesicle stage, and the activities of ∆ 5 -3β-HSD (pregnenolone and 17α-hydroxypregnenolone), 17β-HSD (estradiol-17β), 20α-HSD (20α-hydroxyprogesterone) and 20β-HSD (17α-hydroxyprogesterone) were observed in 57, 64, 65, 61 and 66% of the treated oocytes, respectively. On the other hand, 10, 2, 10, 7 and 2% of control oocytes respectively showed such HSD activities, demonstrating a significantly lower percentage of oocytes showing the HSD activities, compared with the olomoucine-treated oocytes. From the present findings, it was suggested in porcine oocytes that the metabolic abilities of progesterone, 17α-hydroxyprogesterone, 20α-hydroxyprogesterone, 17α,20β-dihydroxyprogesterone and estradiol-17β in the cytoplasm are closely related to nuclear maturation, and the disappearance of their metabolic abilities could be used as a characteristic for the resumption of meiotic maturation. Key words: Porcine oocyte, Meiotic maturation, Hydroxysteroid dehydrogenase, Steroid metabolism, Histochemistry (J. Reprod. Dev. 48: [303][304][305][306][307][308] 2002) t has been reported that steroid metabolism in the cytoplasm alters with nuclear maturation of oocytes. Namely, it has been biochemically confirmed that the activity of ∆ 5 -3β-hydroxysteroid dehydrogenase (∆ 5 -3β-HSD) with pregnenolone as the substrate, which is involved in progesterone metabolism, increases in rat oocytes after germinal vesicle breakdown (GVBD), and that this activity reaches a peak at the time of ovulation, indicating that nuclear maturation in rat oocytes is associated with progesterone metabolism [1]. We [2] have also reported that the activities of ∆ 5 -3β-HSD (using 17α-hydroxypregnenolone as the substrate) and 20β -HSD (17α -hyd rox yprogesterone) were observed in almost all oocytes collected from antral follicles of mice, rabbits, pigs and cattle, and that they disappeared from the oocytes of these animals as nuclear maturation progressed, except for the mouse. From these results, it was inferred that the nuclear maturation of...

Changes in the Activities of Hydroxysteroid Dehydrogenases in Mouse Oocytes during Meiotic Maturation

“…From the results of the present investigation and that of Ta kano and Niimura [3 ], it was confirmed that changes in the metabolic abilities of steroids in oocytes with maturation are different in pigs and mice, and that there are animals with and without a relationship between nuclear maturation and changes in steroid metabolism in the oocytes.…”

“…As already mentioned, the metabolic abilities of progesterone, 17α-hydroxyprogesterone, 17α,20β-dihydroxyprogesterone, 20α-hydroxyprogesterone and estrogen weakened and disappeared in porcine oocytes with the progression of nuclear maturation [3]. From the results of the present investigation and that of Ta kano and Niimura [3 ], it was confirmed that changes in the metabolic abilities of steroids in oocytes with maturation are different in pigs and mice, and that there are animals with and without a relationship between nuclear maturation and changes in steroid metabolism in the oocytes.…”

“…Recently, Takano and Niimura [3] have reported that the rates of porcine oocytes with the activities of ∆ 5 -3β-HSD (DHA), 17β-HSD (testosterone) and 20β-HSD (20 β-hydroxyprogesterone) did not change during maturation culture, whereas those with the activities of ∆ 5 -3β-HSD (pregnenolone and 17α-hydroxypregnenolone), 17β-HSD (estradiol-17β), 20α-HSD (20α-hydroxyprogesterone) and 20β-HSD (17α-hydroxyprogesterone) decreased as the time of culture was prolonged. They have also reported that the resumption of nuclear maturation was completely inhibited in porcine oocytes with olomoucine treatment, and the decrease in number of oocytes with the activities of such HSDs was also inhibited.…”

“…They have also reported that the resumption of nuclear maturation was completely inhibited in porcine oocytes with olomoucine treatment, and the decrease in number of oocytes with the activities of such HSDs was also inhibited. From these results, it was suggested that the nuclear maturation in porcine oocytes was determined to be closely associated with the m e t a b o l i c a b i l i t i e s of p r og e s t e r o n e , 1 7α -hydroxyprogesterone, 20α-hydroxyprogesterone, 17α,20β-dihydroxyprogesterone and estradiol-17β, and the disappearance of these metabolic abilities could serve as a characteristic of the resumption of meiotic maturation [3]. Changes in the metabolic abilities of steroids in mammalian oocytes with maturation have been investigated in rats [1], mice [2], rabbits [2], pigs [2,3] and c att le [2], as mentioned above, though sufficient numbers of different kinds of HSDs were demonstrated only in pigs [3].…”

Expression of genes involved in prostaglandin E2 and progesterone production in bovine cumulus–oocyte complexes during in vitro maturation and fertilization

“…Here, we demonstrate that the level of 20a-HSD mRNA expression, which was high in immature COCs, dramatically decreased throughout the IVM and IVF periods to reach its lowest levels in fertilized COCs. A previous in vitro study of porcine COCs had reported that 20a-HSD activity was closely related to oocyte nuclear status (Takano & Niimura 2002). The 20a-HSD activity present in immature COCs decreased during IVM to disappear at the metaphase II stage.…”