• Animal cells and systems
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• v.11 no.1
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• pp.1-8
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• 2007

Recently, we have shown that some endocrine disruptors, heavy metals, organotins and azoles suppressed steroidogenic enzymes such as P450 side-chain cleavage enzyme (P450scc) and aromatase in bullfrog ovarian follicles. In the present study, by using an amphibian ovarian follicle culture system, we examined the effects of these endocrine disruptors on maturation and ovulation of oocytes from Rana dybowskii in vitro. Ovarian fragments or isolated follicles were cultured for 24 h in a medium containing frog pituitary homogenate (FPH) or progesterone ($P_{4}$) with or without endocrine disruptors, and oocyte maturation (germinal vesicle breakdown, GVBD) and ovulation were examined. Among the organotins, tributyltin (TBT) strongly inhibited both FPH-and $P_{4}-induced$ oocyte maturation ($ED_{50}$:0.6 and 0.7 ${\mu}M$, respectively); however, tetrabutyltin (TTBT) and dibutyltin (DBT) showed only partial suppression, while monobutyltin (MBT) showed no inhibitory effect. All of the organotins suppressed $P_{4}-induced$ oocyte ovulation very effectively at a low concentration, and TBT and DBT exerted an inhibitory effect on FPH-induced ovulation. Among the heavy metals, mercury (Hg), cadmium (Cd) and cobalt (Co) were very effective in inhibiting FPH-induced oocyte maturation and ovulation, while lead (Pb), arsenite (As) and zinc (Zn) were less effective. However, all of the heavy metals suppressed FPH-induced oocyte ovulation at a high dose ($100{\mu}M$). Among the azoles, itraconazole (ICZ), ketoconazole (KCZ) and clotrimazole (CTZ) effectively inhibited FPH-induced oocyte maturation and ovulation, while econazole (ECZ), miconazole (MCZ) and fluconazole (FCZ) were considerably less effective. These results demonstrated that the abovementioned endocrine disruptors exhibited differential effects on oocyte maturation and ovulation in amphibian follicles and that the frog ovarian culture system could be used as an effective experimental tool to screen and evaluate the toxicity of various endocrine disruptors in vitro.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.1
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• pp.41-47
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• 2017

Perhaps the most common type of reproductive dysfunction in captive fish is failure of females to undergo final oocyte maturation and thus to ovulate and spawn. The success of aquaculture could therefore be improved by developing techniques to enhance natural spawning, artificial maturation, and/or to induce ovulation in farmed fish. This study aimed to investigate the effects of prostaglandin $E_2$ ($PGE_2$) and prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) on in vitro oocyte maturation (germinal vesicle breakdown, GVBD) and ovulation in the marine fish Chasmichthys dolichognathus. Post-vitellogenic follicles (0.80-0.94 mm diameter oocytes) were incubated with $PGE_2$ or $PGF_{2{\alpha}}$ at concentrations of 5, 50, or 500 ng/mL for 24 hours. A significant increase in GVBD was seen in 0.84 mm and 0.94 mm oocytes incubated with 50 ng/mL $PGE_2$ compared with the control. There was no significant increase in GVBD in any of the other experimental conditions (5 or 500 ng/mL $PGE_2$ or 5, 50, or 500 ng/mL $PGF_{2{\alpha}}$). Neither of the prostaglandins induced ovulation at the concentrations tested.These results suggest that GVBD was induced by incubation with 50 ng/mL $PGE_2$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.584-587
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• 2001

The effects of tributyltin (TBT), triphenyltin (TPhT) and Aroclor 1254 on germinal vesicle breakdown (GVBD) and ovulation of olive flounder (Paralichthys olivaceus) were investigated in in vitro bioassay. TBT, TPhT and Aroclor 1254 showed the inhibition effects on GVBD and ovulation in response to HCG. The oocyte response appeared to be more sensitive to TBT than Aroclor 1254. TBT was more effective in inhibition GVBD at concentrations of 0.1 and 1 ppm. However, no significant inhibition was obseued in concentrations tested ($0.0001\~1\;ppm$). Significant inhibition of ovulation in response to HCG occurred at TBT (0.01, 0.1, 1 ppm), TPhT (0.01, 0.1, 1 ppm) and Aroclor 1254 (0.01, 1 ppm, except 0,1 ppm), compared to HCG control, The lowest ovulation rate was measured at 1 ppm TBT, These data suggest that TBT (or TPhT) could possibly interfere the actions of progestogens to induce GVBD and ovulation in in vitro bioassay system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.203-210
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• 1997

The aim of this study was to determine the effect of steroids and human chorionic gonadotropin (HCG) on in vitro maturation and ovulation of oocyte in Pseudobagrus fulvidraco. Oocytes were incubated in the media Leibovitz L15 supplemented with the various concentration of $17\alpha,\;20\beta-dihydroxy-4-pregnen-3-one(17\alpha20{\beta}OHP),\;17\alpha-hydroxyprogesterone(17{\alpha}OHP),\;progesterone(P_4),\;estradiol-17\beta(E_2)and\;HCG$. After 60 hours incubation, the maturation ability of oocyte was assessed by the appearance of germinal vesicle breakdown (GVBD). GVBD was significantly enhanced by the addition of $17\alpha20{\beta}OHP,\;17{\alpha}OHP,\;P_4\;and\;HCD(P<0.05)$. The highest CVBD was observed when $17\alpha20{\beta}OHP$ and HCG were supplemented to media. When oocytes were cultured for 16 hours in media containing $10\~1,000\;ng/ml\;17\alpha20{\beta}OHP,\;17{\alpha}OHP\;and\;P_4$, the rate of GVBD in oocytes cultured in the medium supplemented with 100 ng/ml $17\alpha20{\beta}OHP(65\%)$ was significantly higher than that with $17{\alpha}OHP\;(40\%)\;and\;P_4(35\%)$. The efforts of $17\alpha20{\beta}OHP$ and HCG on GVBD were assessed by various concentration of these hormones. When oocytes were cultured for 60 hours in various media containing $1\~1,000\;ng/ml\;17{\alpha}20{\beta}OHP\;or\;5\~1,000\;IU/ml$ HCG, the GVBD of oocytes was significantly increased in the medium with $10\~100\;ng/ml\;17\alpha20{\beta}OHP$ and 500 IU/ml HCT. When oocytes were cultured in the various media supplemented with $1\~1,000\;ng/ml\;17\alpha20{\beta}OHP\;or\;5\~1,000\;IU/ml$ HCG for 60 hours, the media with $1\~100\;ng/ml\;17\alpha20{\beta}OHP\;or\;50\~1,000IU/ml$ HCG significantly increased in the rate of ovulation. However supplementation with $1,000\;ng/ml\;17\alpha20{\beta}OHP$or 5 IU/ml HCG did not improve the rate of ovulation compared to controls. This results indicate that supplementation of steroid and HCG except $E_2$ can improve the in vitro maturation and ovulation of oocyte in P. fulvidrac; HCG and $17\alpha20{\beta}OHP$ may be more effective than other steroids on oocyte maturation and ovulation in P. fulvidraco.

• Molecules and Cells
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• v.40 no.8
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• pp.558-566
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• 2017

Regular monitoring on experimental animal management found the fluctuation of ART outcome, which showed a necessity to explore whether superovulation treatment is responsible for such unexpected outcome. This study was subsequently conducted to examine whether superovulation treatment can preserve ultrastructural integrity and developmental competence of oocytes following oocyte activation and embryo culture. A randomized study using mouse model was designed and in vitro development (experiment 1), ultrastructural morphology (experiment 2) and functional integrity of the oocytes (experiment 3) retrieved after PMSG/hCG injection (superovulation group) or not (natural ovulation; control group) were evaluated. In experiment 1, more oocytes were retrieved following superovulation than following natural ovulation, but natural ovulation yielded higher (p < 0.0563) maturation rate than superovulation. The capacity of mature oocytes to form pronucleus and to develop into blastocysts in vitro was similar. In experiment 2, a notable (p < 0.0186) increase in mitochondrial deformity, characterized by the formation of vacuolated mitochondria, was detected in the superovulation group. Multivesicular body formation was also increased, whereas early endosome formation was significantly decreased. No obvious changes in other microorganelles, however, were detected, which included the formation and distribution of mitochondria, cortical granules, microvilli, and smooth and rough endoplasmic reticulum. In experiment 3, significant decreases in mitochondrial activity, ATP production and dextran uptake were detected in the superovulation group. In conclusion, superovulation treatment may change both maturational status and functional and ultrastuctural integrity of oocytes. Superovulation effect on preimplantation development can be discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.174-183
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• 2001

During the rapid phase of gonadal development of the freshwater teleost, the catfish (Silurus asotus), the influence of hCG upon the inducement of final oocyte maturation and spawning was investigated electrophoretically and ultrastructurally. The electrophoretic patterns obtained were different in the presence and absence of some of the major or minor zones, because of the hormone level in catfish. The vitellogenin of hormone-treated fish was stained more intensively than that of sham-treated fish. These proteins showed some minor or main bands of egg extracts which migrated at positions corresponding to molecular weights of approximately 90,000. However, the thickness of electrophoretic band in molecular weight for hCG-treated fish was slightly lower than that for saline control. It seemed the plasma protein with molecular weight of approximately 45,000 in hCG-treated fish disappeared. In contrast to the control fish, the ovaries in the catfish treated with hCG shows a marked ultrastructural change under the electron microscope. No dilated profiles were seen in the granulosa cells of the mature oocyte before ovulation. After germinal vesicle breakdown (GVBD), the zona radiata interna (ZRI) becomes more compact, and there is a loss of all the processes from the pore canals. There is a wide space between the vitelline membrane and zona radiata. Also, during final maturation, the microvillar processes from the oocyte are seen no longer to penetrate deeply into the extracellular spaces of the overlying granulosa cells, and the reticulate patterns of the zona radiata interna becomes occluded, giving the zona radiata a more solid appearance. It has been possible to initiate 100% oocyte maturation in yolk granules and follicles in vivo by treatment with hCG and a high water temperature ($27^{\circ}C$). In hCG-treated fish, the percentages of successful artificial fertilization and hatching were maximal at 15 h after a single injection. It seems clear that a long acting preparation containing hCG can be successfully used in prespawning fish to advance the final events of gonadal maturation and initiate spawning. Further studies are necessary to evaluate the potential of hCG to either stimulate or inhibit the reproductive development of fish at other stages of the seasonal reproductive cycle.

• Reproductive and Developmental Biology
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• v.38 no.2
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• pp.63-70
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• 2014

Plasminogen activators (PAs) are serine proteases that convert plasminogen to plasmin. Two type of PAs are urokinase-type PA (uPA) and tissue-type PA (tPA). Plasminogen is present in most extracellular fluids. PAs play in various reproductive processes including implantation, ovulation and fertilization. In the spermatozoa, PAs and PAIs play a role in sperm motility and fertilization. PAs in the sertoli cell are stimulated spermatozoa maturation and sperm activation through the phospholipase A2. The oocyte maturation is the process for fertilization and implantation. PAs in cumulus-oocyte complexes (COCs) are related to oocyte maturation by protein kinase A and C. In the ovulatory process, PAs activity are changed and it are related to reducing the tensile strength of ovarian follicle wall. The uterine environment is important for reproduction and the uterus undergo tissue remodeling. In the uterus and oviduct of mammals, expression and activity of PAs are changed during estrous cycle. Thus, expression and activity of PAs are concerned to many reproductive functions. Therefore, PAs seem to important factor of regulator in reproductive events.

• Journal of Aquaculture
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• v.21 no.2
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• pp.96-101
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• 2008

To induce of maturation and ovulation, ovary with different development stage of oocytes of sevenband grouper Epinephelus septemfasciatus(n=51, TL $69.1{\pm}1.0$ cm, BW $5.8{\pm}0.3$ kg) rearing indoor-tank in mature and spawning season(June to July) were investigated by cannulation. Female with yolk globule stage oocyte($300{\sim}500{\mu}m$) was injected with human chorionic gonadotropin(HCG, 500 IU/kg BW). Oocytes developed at diameter $300{\sim}700{\mu}m$ in 24 hrs after the HCG injection, and the distribution ratio of over $800{\mu}m$ of oocytes diameter in the cannulated eggs were $91.3{\sim}98.8%(95.1{\pm}3.7%)$ in 48 hrs after the HCG injection. Ovulation was induced from 7 out of 8 female after the HCG injection. The total volume of stripped eggs was 2,480 mL, and the volume of buoyant eggs was 1,360 mL. The fertilization and hatching rates of buoyant eggs were $56.2{\sim}94.9%$ and $70.7{\sim}97.9%$, respectively. These results suggested that HCG 500 IU/kg BW effects on maturation and ovulation of female sevenband grouper with yolk globule stage of oocyte.

• Clinical and Experimental Reproductive Medicine
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• v.14 no.1
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• pp.7-17
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• 1987

It appears that a major determinant of the success of in vitro fertilization is the selection of the optimal follicle containing an oocyte capable of being fertilized and producing a normal pregnancy. However, the hormonal basis of oocyte maturation is not well substantiated by the as yet available informations. It has been suggested that prolactin(PRL) may stimulate the formation of an oocyte maturation inhibitor and thus inhibit the maturation of oocyte. During the hyperstimulated menstrual cycles serum estradiol($E_2$) levels are markedly elevated, and it seems justified to assume that serum prolactin levels may be elevated since estrogens are potent stimulators of prolactin secretion. This study was carried out to ascertain the effect of the elevated serum estradiol levels on the serum prolactin levels in women undergoing ovarian hyperstimulation with either hMG and/or clomiphene citrate. Serum estradiol and prolactin profiles were measured from third menatrual cycle day to ovulation or ovum aspiration day in 11 normal menstruating women and 30 women who underwent an in vitro fertilization procedure with ovarian hyperstimulation by hMG, clomiphene citrate/hMG, clomiphene citrate. Ovum aspiration was performed 36 hours after hCG administration. The day of ovum aspiration or ovulation was designated Day 0. Serum estradiol levels increased progressively during the follicular phase and this rise peaked on Day-1 at a mean concentration of 1,204${\pm}$189.0pg/ml in Group II(hMG), 1,194${\pm}$167.9pg/ml in Group III(clomiphene citrate/hMG), 1,035${\pm}$195.1pg/ml in Group IV(clomiphene citrate) respectively and on Day -2 of 336${\pm}$34.5pg/ml in Group I(normal control). The elevated estradiol levels fen rapidly after ovulation or ovum aspiration. Serum estradiol values of hyperstimulated groups(Group II, III, IV) were significantly higher than that of control group(Group I) from Day -6 to Day +1, but there was no significant difference of estradiol values among the hyperstimulated groups. Serum prolactin levels increased and peaked on Day +1 at a mean concentration of 60.8${\pm}$14.4ng/ml in Group II, 34.2${\pm}$7.0ng/ml in Group III, 30.1${\pm}$5.7ng/ml in Group IV respectively, but no significant elevation was observed in Group I. Levels of estradiol and prolactin can be positively and significantly correlated in the hyperstimulated groups. However, the increase of serum prolactin levels in hMG group was significantly higher than those in clomiphene citrate/hMG or clomiphene citrate group.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.8
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• pp.1065-1074
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• 2016

Growth factors play an important role during early ovarian development and folliculogenesis, since they regulate the migration of germ cells to the gonadal ridge. They also act on follicle recruitment, proliferation/atresia of granulosa cells and theca, steroidogenesis, oocyte maturation, ovulation and luteinization. Among the growth factors, the growth differentiation factor 9 (GDF9) and the bone morphogenetic protein 15 (BMP15), belong to the transforming growth factor beta (TGF-${\beta}$) superfamily, have been implicated as essential for follicular development. The GDF9 and BMP15 participate in the evolution of the primordial follicle to primary follicle and play an important role in the later stages of follicular development and maturation, increasing the steroidogenic acute regulatory protein expression, plasminogen activator and luteinizing hormone receptor (LHR). These factors are also involved in the interconnections between the oocyte and surrounding cumulus cells, where they regulate absorption of amino acids, glycolysis and biosynthesis of cholesterol cumulus cells. Even though the mode of action has not been fully established, in vitro observations indicate that the factors GDF9 and BMP15 stimulate the growth of ovarian follicles and proliferation of cumulus cells through the induction of mitosis in cells and granulosa and theca expression of genes linked to follicular maturation. Thus, seeking greater understanding of the action of these growth factors on the development of oocytes, the role of GDF9 and BMP15 in ovarian function is summarized in this brief review.