Effect of RU486 on collagenolytic enzyme activities in immature rat ovary

To investigate the role of progesterone (P) in the ovulatory process, RU486 (RU) (10mg/kg), an antiprogesterone, was administered to PMS-hCG-treated immature female rats (22 days old). As for the collagenolytic enzymes (CE), the activities of BANA hydrolase and DNP peptidase were measured by using synthetic substrates alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl and DNP Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH, respectively. Serial assays were performed at 0, 2, 4, 6, 7, 8, 9, 10 and 12 hours after the hCG injection. In the control, the CE activities were significantly increased after the hCG injection at 8-9 hours in BANA hydrolase and 7-10 hours in DNP peptidase, respectively. By administering RU concomitant with hCG, the preovulatory increase in the CE activities was totally suppressed. Following the P(10mg/kg) injection at 4 hours after hCG and RU injections, the CE activities showed the greatest recovery, approaching the control range. In the ovulatory process of the rat ovary, P plays an important role through its regulatory effects on the collagenolytic enzymes, and this P effect seems to be most prominent around 4 hours after a LH surge.     

Effect of indomethacin on collagenolytic enzyme activities in rabbit ovary

To investigate the possible participation of prostaglandins in the activation of collagenolytic enzymes of the follicular wall at ovulation, we measured the activities of neutral and acid collagenase in the rabbit ovaries at various stages of follicular development by using synthetic substrate DNP-Pro-Gln-Ile-Ala-Gly-Gln-D-Arg OH (DNP peptide) with its optimal pH 7.6 and alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl (BANA) with pH 6.0, and the effect of ovulation-blocking doses of indomethacin (4 mg/kg) on DNP peptidase and BANA hydrolase activities were investigated. DNP peptidase and BANA hydrolase activities were increased toward ovulation with the highest level 7 to 9hrs after the hCG injection and then decreased significantly at 10hr. At 11hr, around the time of ovulation, the activity stayed at its low level, then rose by 13hr. Following the concomitant administration of IM with hCG, ovulation was blocked and the preovulatory increases in DNP peptidase and BANA hydrolase activities were not observed and their activities stayed at the low level until 20hr. It is suggested that collagenolytic activity for the ovulatory process started to intensiby 6hrs and ended 3hrs prior to ovulation and PGs are necessary for the enzymatic activation of DNP peptidase and BANA hydrolase.     

Studies on the regulation of steroid biosynthesis in the rat ovary

The stimulatory effect of gonadotropins on steroid hormone production by the ovary is generally considered to be the result of an activation of the cholesterol side chain cleaving enzyme. The present study was undertaken to investigate whether the enzymic action of 3 beta-HSD and 20 alpha-HSD could be directly stimulated by hCG and/or PRL. Female immature rats were used. The ovaries were stimulated by PMSG injection to allow uniform growth of the follicles. The effect of hCG was evaluated both in in vivo and in vitro studies. The 3 beta-HSD activity in the ovarian tissue homogenate or dispersed cells was estimated from the rate of conversion of 14C-pregnenolone to 14C-progesterone in an in vitro incubation experiment. The activity of 20 alpha-HSD was measured by the conversion rate of 14C-progesterone to 14C-20 alpha-hydroxy-4-pregnen-3-one, hCG apparently stimulated the 3 beta-HSD activity both in vivo and in vitro. Under certain experimental conditions, PRL enhanced the stimulatory effect of hCG on 3 beta-HSD. Both hCG and PRL stimulated the 20 alpha-HSD activity. Intrinsic steroids, such as estrogens, androgens, and 20 alpha-hydroxy-4-pregnen-3-one, a major progestin in rodents, in the synthesis of steroid hormones was its inhibitory effect upon 3 beta-HSD.     

Collagenolytic enzyme activity in human ovary: an ovulatory enzyme system

Collagenolytic enzyme activities presumed to play an important role in ovulation were investigated in the human follicular apex, base, and granulosa cell layer throughout the ovarian cycle. Those analyzed were human ovarian collagenase, 2,4-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH peptidase, N-carbobenzoxy-Gly-Pro-Gly-Gly-Pro-Ala peptidase, and alpha-N-benzoyl-DL-arginine beta-naphthylamide hydrolase. Collagenase activity was also measured in human granulosa cell cultures. The activities of all four enzymes showed a marked preovulatory decrease in the apex. The activities in the apex were slightly higher than those in the base throughout the ovarian cycle. However, the activities in the granulosa cell layer and collagenase activity in the granulosa cell cultures increased toward preovulation and decreased after ovulation. These findings suggest that collagenase is synthesized in the granulosa cells maximally at preovulation and is consumed in the follicular apex at the same time, resulting in collagen degradation and disruption of the follicular wall in collaboration with other collagenolytic enzymes investigated here.     

Autoradiographic study on the distribution of gonadotropin-releasing hormone receptor in the rat ovary

Autoradiographic studies were undertaken to clarify the distribution and regulatory mechanisms of GnRH receptors in the ovary of the immature rat during sexual maturation. Iodinated GnRH analog (GnRHa) was injected intravenously and the uptake and distribution of the GnRHa in the ovary were examined. The uptake rate for GnRHa in the ovary increased gradually from 7 days to 21 days of age and declined by 49 days of age. The uptake of GnRHa increased in the ovary of the hypophysectomized rat (28 days old) treated with GnRH and decreased in those treated with PMSG. In the autoradiographic study, silver grains were detected in the ovary, that is the theca cells and the interstitial tissue as well as the granulosa cells. GnRHa bound predominantly to the interstitial tissues before 21 days of age, but GnRHa bound to the granulosa cells more than the theca cells and the interstitial tissue after 28 days of age, corresponding with the prepubertal decrease in GnRHa uptake in the ovary. These results suggest that the distribution of GnRH receptor in the ovary changes with follicular development during sexual maturation.     

Ovarian enzyme activities in women with polycystic ovary syndrome

Studies using primary ovarian tissue and cultured human theca and granulosa cells have shown that steroidogenic enzyme activities are up-regulated in theca cells in polycystic ovary syndrome (PCOS). Although granulosa cells in arrested follicles in PCOS fail to express significant amounts of aromatase, there is an overexpression of 5alpha-reductase activity and premature expression of cholesterol side-chain cleavage cytochrome P450.     

The effect of edaravone on ischemia-reperfusion injury in rat ovary

Objective

The aim of this study was to investigate the effect of edaravone on experimentally induced ovarian torsion/detorsion ischemia/reperfusion (I/R) injury.

Study design

: Forty-six female adult Wistar-Albino rats were utilized to create five groups: In group 1, only 5 mg/kg edaravone was given and ovary torsion was not performed. In group 2, torsion was not performed and no drug was given. In group 3, vehicle was given and torsion/detorsion was performed. In group 4, 1 mg/kg edaravone was given and torsion/detorsion was performed. In group 5, edaravone; 5 mg/kg drug was administered and torsion/detorsion was performed. Right ovarian torsion was simulated for a 3-h period of ischemia and a 1-h reperfusion period. Right ovaries were then surgically extirpated in all groups. In ovarian tissue samples malondialdehyde (MDA) levels and activity of superoxide dismutase were studied. Microscopic ovarian tissue damage was scored by histologic and electron microscopic findings.

Results

The MDA level in the group 5 was significantly lower than group 3 (p < 0.001). Superoxide dismutase activity in the group 5 was significantly higher than group 3 (p < 0.001). Histopathological ovarian tissue damage in the group 5 were significantly lower than group 3 (p < 0.001).

Conclusion

These results indicate that edaravone could be an effective agent in the short-term treatment and prevention of ovarian ischemia and reperfusion damage.     

Protective effect of aprotinin on ischemia-reperfusion injury in rat ovary

AIM: We investigated the effects of aprotinin on reperfusion injury in a controlled experimental rat torsion-detorsion model. METHODS: Thirty-two female Sprague-Dawley rats were divided into four groups. Sham operation was performed in group I; in group II only ovarian torsion was performed. In group III, torsion-detorsion was performed, plus 3 mL/kg saline was injected i.v. 30 min before detorsion. In group IV, torsion-detorsion was performed, plus aprotinin (30,000 KIU/kg) was injected 30 min before detorsion. Rats in the torsion group were killed after 360 degrees clockwise adnexial torsion for 3 h, and the ovaries were harvested. After 3 h of adnexial detorsion, the rats in the saline and aprotinin groups were killed and the adnexa were surgically removed. RESULTS: Ovarian tissue damage scores were significantly different among groups. Ovarian tissue and serum malondialdehyde levels in group III were significantly higher than those of groups I and IV (P<0.05). The serum levels of superoxide dismutase in group III were significantly lower than those of groups I and IV (P=0.01). Tissue and serum xanthine oxidase, nitric oxide, and tissue superoxide dismutase levels were comparable among groups (P>0.05). CONCLUSIONS: Aprotinin attenuates ischemia-reperfusion injury in a rat adnexial torsion-detorsion model.     

Effect of aromatase inhibitors on the histology of the cycling rat ovary

Two aromatase inhibitors, 4-hydroxyandrostenedione (4-OHA) and testololactone (Teslac), were tested to determine their effects on folliculogenesis, particularly ovarian histologic alterations, in the cycling rat. Adult, female Sprague-Dawley rats were treated with continuous infusion of both inhibitors at concentrations of 10(-8), 10(-4), and 10(-2) M for 30 days. The effect of the inhibitors on cultured granulosa cells harvested on proestrus was determined in vitro. The in vivo administration of each inhibitor induced significant reduction in ovarian-vein estradiol levels. Estradiol synthesis in cultured granulosa cells was inhibited by both aromatase inhibitors in a dose-dependent fashion. These observations indicate that 4-OHA and Teslac significantly inhibit basal estradiol synthesis in vivo and in vitro. This effect on estrogen synthesis was not reflected in alteration of the ovarian histology in the cycling rat.     

Gene expression of gonadotropin releasing hormone in the rat ovary

Although there have been several reports indicating the existence of GnRH or GnRH-like substance in the rat ovary, its synthesis as well as its physiological role in the ovary still remains unknown. In the present study, GnRH mRNA in the rat ovary was examined by using a cRNA probe complementary to the gene of the rat GnRH. The hybridizing band of 700bp was found in the extract from the rat ovary by northern blotting with 32P-labeled GnRH cRNA. In situ hybridization with 35S-labeled cRNA revealed that the site of synthesis of GnRH was granulosa cells and its synthesis was stimulated by the administration of PMSG. These results suggest that GnRH is synthesized in the rat ovary and may play a role in the local regulation of ovarian function.     

The in vitro perifused rat ovary: II. Role of oxygen tension in the whole and quartered ovary

In vitro perifusion of whole ovaries raises questions about tissue viability and its effects on the observed ovarian steroid secretion. To assess effects of tissue degeneration, whole and quartered ovaries from pregnant mare serum gonadotropin (PMSG-) treated immature rats were perifused for 8 h, employing various levels of pO₂. Histological examination of both the whole and quartered ovary showed signs of degeneration in centrally located follicles but not in follicles located near the surface. However, basal and gonadotropin-stimulated (luteinizing hormone plus follicle stimulating hormone) secretion of estradiol, testosterone and progesterone were not significantly different in the whole ovary whether in the presence of high or low PO₂ (n=8; p > 0.05). Similarly, although the quartered ovary secreted greater amounts of steroids than did the whole ovaries (p < 0.05, n=8), pO₂ levels did not affect the steroid output. We conclude that during in vitro perifusion, minimal oxygen supply is sufficient for ovarian steroidogenesis to proceed. In addition, although quartered ovaries displayed some evidence of tissue degeneration, they were more responsive in terms of steroid output per mg ovary than were whole ovaries.     

Troglitazone is a competitive inhibitor of 3beta-hydroxysteroid dehydrogenase enzyme in the ovary

OBJECTIVE: Troglitazone is a potent inhibitor of progesterone release from porcine granulosa cells. This is associated with a marked increase in pregnenolone secretion, implicating inhibition of the 3beta-hydroxysteroid dehydrogenase enzyme. This study determined whether troglitazone is a direct inhibitor of 3beta-hydroxysteroid dehydrogenase activity. STUDY DESIGN: Homogenates of porcine granulosa cells underwent classic enzyme kinetic analysis through Lineweaver-Burke and Dixon plotting. Human ovarian homogenates were also assayed for the effects of troglitazone on 3beta-hydroxysteroid dehydrogenase enzyme activity. Enzyme kinetics data were analyzed by the HyperKinetics software program. Analysis of variance was used to determine statistical significance for human ovarian homogenate experiments. RESULTS: In porcine granulosa cells Lineweaver-Burke analysis found that troglitazone inhibition of 3beta-hydroxysteroid dehydrogenase enzyme activity was competitive in nature, with 5 microg/mL troglitazone increasing the apparent Michaelis constant from 1.3 to 4.3 micromol/L (no change in maximum velocity). Dixon plot analysis demonstrated that the inhibition constant for troglitazone of 3beta-hydroxysteroid dehydrogenase is approximately 6.5 microg/mL, which is in the same order of magnitude as its therapeutic concentration in blood. Troglitazone also significantly decreased the activity of 3beta-hydroxysteroid dehydrogenase in homogenates of human ovarian tissue. CONCLUSION: We conclude that troglitazone can inhibit steroidogenesis in the ovary by direct competitive inhibition of 3beta-hydroxysteroid dehydrogenase.     

化学药物对卵巢组织及功能的影响

自４０年代Ｇｉｌｍａｎ和Ｐｈｉｌｉｐｓ首次应用氮芥治疗恶性肿瘤以来,恶性肿瘤的化学治疗（化疗）取得了很大进展,成为治疗恶性肿瘤的重要手段之一。但对于需保留卵巢的患者,常由于化疗发生卵巢功能早衰,过早出现闭经及更年期症状。本文拟对目前最常见的几种非妇科...     

Effects of prostacyclin on ovulation and microvasculature of the in vitro perfused rabbit ovary

Prostacyclin (prostaglandin I2) methyl ester at 0.1, 1, or 10 micrograms/ml was added to the perfusate of one rabbit ovary every 2 hours for the first 10 hours of perfusion. The contralateral ovary was perfused with medium alone. Prostacyclin methyl ester at 1 and 10 micrograms/ml induced ovulation in the absence of gonadotropin, with ovulatory efficiencies of 26.7% +/- 3.8% and 46.5% +/- 5.0%, respectively. Most ovulated ova (77.4%) did not progress beyond the germinal vesicle stage, and there was no significant degeneration of ovulated ova or follicular oocytes. Examination of the follicular microvasculature 5 hours after exposure to prostacyclin revealed marked vessel dilatation and filling defects at the apex. By 7 hours after prostacyclin exposure, the intrafollicular space contained extravasated resin, reflecting increased vascular permeability. The vascular changes paralleled those previously observed in gonadotropin-induced ovulation. These results indicate that prostacyclin acting locally alters the vascular integrity of the follicle wall and facilitates follicle rupture.     

Children of hyper- and hypothyroid mothers

A multicenter study was able to utilize 120 medical files of children born from mothers who presented an abnormal thyroid function, 67 euthyroid goiters, 29 hyperthyroidisms, and 24 hypothyroidisms. In the first case, whether or not an inhibiting treatment was initiated, all children were perfectly normal. In case of maternal hyperthyroidism, the risk of malformations is not increased, deaths in utero and mostly in utero growth delays (1 case in 2) are more frequent. At birth, the child may present a hyperthyroidism due to the effect of SAT with elevated TSH and a goiter, sometimes compressing and impairing breathing, or also a hyperthyroidism due to transplacental crossing of stimulating immunoglobulins with possibility of thyreotoxic crises and heart failure. The diagnosis could be made in utero in the presence of tachycardia or with T4 and TSH assays in the cord. In case of maternal hypothyroidism, usually the children have no problems and the risk of neonatal hypothyroidism is mostly present in premature infants if the maternal balance is poor (2 in 24 cases in our series). Finally, in the reference population, the risk of neonatal hypothyroidism remains 1 in 3600 and justifies systematic screening on the 5th day of life.