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At least 19 recordsLinked to original sources
PubMed1999

Isolation, characterization and molecular cloning of cathepsin D from lizard ovary: changes in enzyme activity and mRNA expression throughout ovarian cycle.

During vitellogenesis, the oocytes of oviparous species accumulate in the cytoplasm a large amount of proteic nutrients synthetized in the liver. Once incorporated into the oocytes, these nutrients, especially represented by vitellogenin (VTG) and very low-density lipoprotein (VLDL), are cleaved into a characteristic set of polypeptides forming yolk platelets. We have studied the molecular mechanisms involved in yolk formation in a reptilian species Podarcis sicula, a lizard characterized by a seasonal reproductive cycle. Our results demonstrate the existence in the lizard ovary of an aspartic proteinase having a maximal activity at acidic pH and a molecular mass of 40 kDa. The full-length aspartic proteinase cDNA produced from total RNA by RT-PCR is 1,442 base pairs long and encodes a protein of 403 amino acids. A comparison of the proteic sequence with aspartic proteinases from various sources demonstrates that the lizard enzyme is a cathepsin D. Lizard ovarian cathepsin D activity is maximal in June, in coincidence with vitellogenesis and ovulation, and is especially abundant in vitellogenic follicles and in eggs. Ovarian cathepsin D activity can be enhanced during the resting period by treatment with FSH in vivo. Northern blot analysis shows that cathepsin D mRNA is exceedingly abundant during the reproductive period, and accumulates preferentially in previtellogenic oocytes.

Amino Acid Sequence↗
PubMed1999

Recurrent clear cell carcinoma of the ovary changing into producing parathyroid hormone-related protein (PTH-rP) with hypercalcemia.

We experienced the case of a clear cell carcinoma of the ovary arising from an endometrial cyst, which started to produce parathyroid hormone-related protein (PTH-rP) in a recurrent tumor, thus inducing hypercalcemia. Using immunohistochemical analysis, we demonstrated that the primary carcinoma was immunonegative for PTH-rP, but that the recurrent carcinoma was strongly immunopositive for PTH-rP.

Adenocarcinoma, Clear Cell↗
PubMed1991

Release of norepinephrine from the cat ovary: changes after ovulation.

The distribution of intraneuronal constituents involved in norepinephrine (NE) storage, uptake, and release were used to estimate changes in NE secretion from the cat ovary after ovulation induced with eCG plus hCG. The content of NE and ATP, which are principally stored in small noradrenergic vesicles (isolated at a density of 1.041 g/ml in Percoll gradient), decreased after ovulation. However, the activity of dopamine beta-hydroxylase, which is principally associated with large noradrenergic vesicles (isolated at a density of 1.033 g/ml in Percoll gradient), was only slightly decreased. Mg(2+)-dependent ATPase, located in both large and small storage vesicles, decreased only in the small storage vesicles, suggesting that preferential secretion from small noradrenergic vesicles occurred. The hormonal treatment also affected the functional capacity of the vesicles, as evidenced by the decrease in uptake and storage capacity as well as the decrease in the stimulated release of 3H-NE observed after ovulation. The aforementioned changes are characteristically seen after a sympathetic discharge; thus they strongly support the notion that ovarian sympathetic activity increases during the ovulatory process, resulting in the postovulatory decrease in both the size and functional capacity of the intraneuronal compartment where NE is stored.

Adenosine Triphosphate↗
PubMed1997

Progesterone-induced atresia of the proestrous dominant follicle in the bovine ovary: changes in diameter, insulin-like growth factor system, aromatase activity, steroid hormones, and apoptotic index.

The objective was to determine whether there were decreases in insulin-like growth factors (IGF)-I and -II and increases in low-molecular-mass IGF-binding proteins (IGFBPs) in association with an inhibition of aromatase activity (AA) and follicular fluid estradiol (E2) production during progesterone (P4)-induced dominant follicle atresia in cattle. Twelve cycling cows received a norgestomet ear implant at proestrus for 9 days and were assigned to control (n = 3) or P4-treated (n = 9) groups. Injections of P4 (150 mg, i.m.) were given on Days 3 and 4; Days 3, 4, and 5; or Days 3, 4, 5, and 6 of the implant period. Controls received injections of corn oil on Days 3, 4, 5, and 6. Ultrasonography of the dominant follicle and blood sampling were done daily. Unilateral ovariectomy was done one day after the last injection. The experiment was repeated with the remaining ovary (6 follicles/treatment group). Granulosa cells were cultured with radiolabeled testosterone to measure AA. Steroid hormones, IGF-I, and IGF-II were measured in follicular fluid by RIA. The follicular fluid IGFBP profile was quantified by Western ligand blotting. P4-treated cows showed a drastic reduction in AA in the dominant follicles, and follicular fluid E2 was several times lower than in controls. Moreover, in P4-treated groups, concentrations of follicular fluid IGF-I and IGF-II were lower than in controls. The quantity of low-molecular-mass follicular fluid IGFBPs increased in P4-treated groups. Accumulation of low-molecular-mass IGFBPs with a reduction in IGFs may be a mechanism of dominant follicle atresia during the bovine estrous cycle.

Animals↗
PubMed1988

The effect of hypophysectomy on inhibin production by adult rat ovaries: changes in ovarian inhibin gene expression and serum inhibin.

We have investigated the effect of hypophysectomy on adult rat ovarian inhibin alpha- and beta A-subunit mRNA, serum inhibin, and circulating gonadotrophin levels. Immediate declines in ovarian inhibin gene expression and serum inhibin were observed following hypophysectomy, with a nadir on day 4. However, inhibin synthesis determined by these parameters was still apparent at 16 days post-hypophysectomy. Gonadotropin levels were suppressed following hypophysectomy and the fall in inhibin production was highly correlated with disappearance of FSH from the circulation. This study demonstrates that removal of pituitary gonadotropin stimulation results in diminished ovarian inhibin synthesis and provides further evidence indicating that FSH stimulates granulosa cell inhibin synthesis by enhancing inhibin gene transcription.

Animals↗
PubMed1992

Changes in cAMP-dependent phosphorylation of specific cytosol protein in the peri- and postmenopausal ovary.

Changes in cAMP-dependent phosphorylation of 53 kDa protein in a human ovary with respect to the aging process were studied. The phosphorylation of endogenous proteins in ovarian cytosol decreased with aging. However, ovarian aging was accompanied by an increase in the cAMP-dependent phosphorylation of 53 kDa specific protein while the amount of this protein decreased with aging. The plasma gonadotropin levels of women with regular menstrual periods were significantly different from those of women whose menstrual periods had in the recent past become irregular (FSH: p less than 0.01; LH: p less than 0.05); however, there was no significant difference in the plasma estradiol levels between these two groups. Our data show the possible correlations between the non-steroidal ovarian factor (53 kDa protein) and/or its phosphorylation by cAMP-dependent protein kinase and the ovarian aging process.

Adult↗
PubMed1976

Effects of indomethacin and aminoglutethimide phosphate in vivo on luteinizing-hormone-induced alterations of cyclic adenosine monophosphate, prostaglandin F, and steroid levels in preovulatory rat ovaries.

Changes in levels of cyclic adenosine monophosphate (cAMP), prostaglandin F (PGF), progesterone, testosterone, and estradiol-17beta, in preovulatory rat ovaries induced by exogenous luteinizing hormone (LH) have been measured. Ovarian cAMP reached maximal levels 15 min and 1h after LH administration by intravenous and intraperitoneal routes, respectively, and then declined to pre-LH levels by 8 h. Progesterone levels in ovaries and serum rose approximately in parallel with cAMP, but remained elevated throughout the 8-h sampling period. Ovarian testosterone increased to maximal levels 1 h after LH injection, followed by a rapid decline to below pre-LH levels. Ovarian estradiol-17beat concentrations declined steadily throughout the sampling period, reaching almost undetectable levels 8 h after LH treatment. Elevated ovarian PGF levels were observed only at the 4- and 8-h sampling times. Indomethacin treatment, 1 h before LH, prevented the LH-induced increase in ovarian PGF levels, depressed PGF values considerably in saline-injected controls but produced no significant inhibition of ovarian cAMP and progesterone levels. Aminoglutethimide phosphate depressed ovarian concentrations of all three steroids (progesterone, testosterone, and estradiol-17beta) to essentially undetectable levels, both in control and LH-injected rats, but did not alter the LH-induced changes in ovarian cAMP and PGF levels. These observations support the concept of cAMP as a mediator of the LH-induced alterations of ovarian steroidogenesis in vivo during the preovulatory period, but argue against an obligatory role of PGF in this process.

Aminoglutethimide↗
PubMed1991

Comparison of glucose-6-phosphate dehydrogenase activity in healthy and atretic follicles in rat ovary.

Changes in the glucose-6-phosphate dehydrogenase activity have been determined in relation to atresia of Graafian follicles in the rat ovary. Induction of atresia in follicles either due to absence of hCG in the hormonally stimulated immature ovaries or by repeated injections of pentobarbitone sodium to proestrous rats caused significant rise in the enzyme activity. Measurement of enzyme activity in isolated follicular compartments of healthy and atretic follicles revealed that it is significantly higher in the thecal tissue than the granulosa. Increase in enzyme activity in the atretic follicles than the healthy ones occurs due to its rise both in theca and granulosa cells. The significance of these changes in the enzyme activity in healthy and atretic follicles are discussed in relation to the precocious luteinization of cells in the follicular envelope with the onset of atresia.

Animals↗
PubMedDate not supplied

Histochemical changes in acid and alkaline phosphatase activities in the growing follicles and corpora lutea of the rat ovary.

Changes in acid and alkaline phosphatase activities are studied histochemically in different components of the growing follicles and corpora lutea of different generations. Theca cells of the growing follicles showed strong acid phosphatase activity as compared to that observed in the oocyte and granulosa cells. Alkaline phosphatase activity is localized only in the theca interna cells of growing follicles. However, after ovulation with the formation of corpora lutea, the granulosa lutein cells also showed this activity. Changes in the histochemical distribution of the acid and alkaline phosphatases in the follicles and corpora lutea are discussed in relation to folliculogenesis and corpus luteum and regression.

Acid Phosphatase↗
PubMed1999

Characterization of zebrafish primordial germ cells: morphology and early distribution of vasa RNA.

Research into germ line development is of conceptual and biotechnologic importance. In this study, we used morphology at the level of light and electron microscope to characterize the primordial germ cells (PGCs) of the zebrafish throughout embryonic and larval development. The study was complemented by the detailed analysis of mRNA expression of a putative germ line marker vasa. By morphology alone PGCs were identified at the earliest at the 5-somite stage in the peripheral endoderm in contact with the yolk syncytial layer. Subsequently, they move from lateral to medial positions into the median mesoderm and from there by means of the dorsal mesentery into the gonadal anlage at day 5 postfertilization (pf), to establish gonads with mesenchymal cells by day 9 pf. Ultrastructural analysis of the 4-day-old zebrafish larvae demonstrates the presence of the germ line-specific structures, nuage, and annulate lamellae. vasa RNA-positive cells can be followed during zebrafish embryogenesis from the 32-cell stage onward (Yoon et al., 1997). Upon completion of gastrulation, the RNA is exclusively present in the cells of the hypoblast, which as a consequence of convergence and extension movements first arrange themselves in a V-shaped string-like conformation to end up, by late somitogenesis, as a string of cells on each side of the midline. We show that the localization of maternal vasa RNA in the ovary changes from cytoplasmic, in the previtellogenic oocytes, to cortical in the vitellogenic oocytes, to concentrate at the boundary of the yolk and cytoplasm in the one cell stage zygote. These results demonstrate that the cortical vasa RNA localization precedes its cleavage furrow-associated localization in the embryos and is presumably cytoskeleton dependent. vasa RNA localization changes from asymmetric subcellular at the sphere stage, to become entirely cytoplasmic at the dome stage. These data suggest a close resemblance in modes of segregation of the germ plasma in the frog and vasa mRNA in the fish during cleavage stages. Based on the significantly larger size and the stereotype and similar position of morphologically distinct cells, presumed to be PGCs, and their vasa RNA-positive counterparts, we conclude that vasa RNA-positive cells are the PGCs and vasa RNA represents a definitive germ line marker in the fish. Dev Dyn 1999;216:153-167.

Animals↗
PubMed1990

Plasma levels of ovarian steroids, including 17 alpha-20 alpha-dihydroxy-4-pregnen-3-one and 3 beta,17 alpha,20 alpha-trihydroxy-5 beta-pregnane, in female dabs (Limanda limanda)--marine flatfish--induced to mature and ovulate with human chorionic gonadotrophin.

Human chorionic gonadotrophin (HCG) effectively stimulated oocyte final maturation and ovulation in female dabs (Limanda limanda) within 5 days of injection, and this was accompanied by significant changes in blood plasma steroid levels. The steroids which showed the greatest responses to the HCG injections were the ones previously found to be the major products of the ovaries in vitro: 17 alpha-20 alpha-dihydroxy-4-pregnen-3-one (17,20 alpha-P) and 3 beta,17 alpha,20 alpha-trihydroxy-5 beta-pregnane (3 beta,17,20 alpha-P-5 beta). 17,20 alpha-P responded more rapidly with peak levels after 32 hr of injection (115 ng ml-1), but 3 beta,17,20 alpha-P-5 beta reached higher levels ca. 12 hr later (320 ng ml-1). Levels of both steroids were not significantly different from initial values by the time of ovulation. 17 alpha,20 beta-Dihydroxy-4-pregnen-3-one, which is likely to be the oocyte maturation-inducing steroid (MIS) in the dab, showed a significant but very variable rise in levels (between 1 and 10 ng ml-1 in individual fish). 17 alpha-Hydroxy-4-pregnene-3,20-dione levels peaked at 6 ng ml-1 between 30 and 36 hr after HCG injection. Of the other C21 steroids identified in the ovaries of teleosts, 17 alpha,20 beta-21-trihydroxy-4-pregnen-3-one could not be detected, and 17 alpha,21-dihydroxy-4-pregnene-3,20-dione (11-deoxycortisol) showed nonsignificant changes compared to the saline-injected controls. HCG caused a decrease in estradiol-17 beta levels within 24 hr, but levels then rose again to a maximum of 8.2 ng ml-1 at ovulation time, possibly caused by the presence of vitellogenic oocytes in the ovaries. Changes in testosterone levels, however, were not significantly different between HCG- and saline-injected females. The role of HCG-responsive C21 steroids in the dab is discussed.

Animals↗
PubMed1988

Concanavalin A reactivity of vitellogenin and yolk proteins of the threespined stickleback Gasterosteus aculeatus (Teleostei).

1. Concanavalin A (con A) reactive proteins have been detected in the plasma and ovaries of the oestradiol treated Gasterosteus aculeatus. 2. Concanavalin A-horseradish peroxidase (HRP) technique applied on nitrocellulose membranes reveals that vitellogenin (Vg) is the only mannose and glucose rich glycoprotein present in the plasma of oestradiol treated sticklebacks. Stickleback Vg can be purified by con A-Sepharose chromatography. 3. Con A reactivity in the ovary changes in the course of development of the oocytes. First, the yolk vesicles, which are synthesized by the oocyte itself, become con A positive. Later, the yolk granules, which contain vitellogenin synthesized in the liver and taken up from the plasma, show a clear affinity for con A. Con A staining disappears when mannopyranoside is added. 4. No con A staining is found in the periodic acid/Schiff staining chorion.

Animals↗
PubMed2000

Localization of the progesterone receptor in the porcine ovary.

Regulation of progesterone receptor (PR) expression has been studied in many species. However, precise studies have not yet been performed in the porcine ovary. We have examined the localization of PR in follicles and corpora lutea of the porcine ovary at different stages of their development. The effects of LH and FSH on PR expression in granulosa cells of small antral follicles was also studied. Immunohistochemistry was applied to determine the distribution of PR while immunoblot analysis showed that two isoforms A and B were present. Early antral follicles contained PR in the granulosa layer. In granulosa cells of small and medium antral follicles PR was not detected whereas it was present in the theca layer. Before ovulation, PR was found in both granulosa and theca cells of large follicles and the staining intensity was very strong. FSH or LH treatment of small follicles (100 ng/ml) induced changes in cellular distribution patterns of PR. In both cases, PR was expressed in granulosa cells. PR was detected in corpora lutea in all 3 stages of the luteal phase. Our data show that in the pig ovary changes in PR localization are stage-specific and suggest that expression of PR is positively regulated by both LH and FSH.

Animals↗
PubMed2001

Estrogen receptor beta in the sheep ovary during the estrous cycle and early pregnancy.

Objectives were to sequence and examine the expression of the estrogen receptor beta (ERbeta) in the sheep ovary. The sequence of the ovine ERbeta (oERbeta) was determined using reverse-transcription polymerase chain reaction (RT-PCR) and cloning techniques. The reading frame of oERbeta contained 527 amino acids and exhibited high overall homology with cow (98%), rat (88%), and human (88%) ERbeta. In addition, an oERbeta isoform having a 139-base pair deletion (oERbeta1) was identified. The predicted amino acid sequence of this isoform is lacking the ligand-binding and carboxyl-terminal transactivation domains. The oERbeta protein and mRNA were determined in ovaries obtained from ewes on Days 0 (first day of estrus), 2, 6, and 10 of the estrous cycle and Day 30 of gestation. Immunohistochemistry showed that oERbeta protein was located in granulosa cells, the ovarian surface epithelium, endothelium, and Day 2 corpus luteum (CL). Weak immunostaining for ERbeta was detected in the theca interna. Relative steady-state amounts of oERbeta mRNA in the CL were determined using semiquantitative RT-PCR. Amounts of oERbeta mRNA were greater (P < 0.05) during CL formation (Day 2) than at later stages. The oERbeta to oERbeta1 mRNA ratio was lower (P < 0.05) on Day 2 than on Day 10 or Day 30 due to a decrease in amounts of oERbeta1. Results indicate that the oERbeta is a 527-amino acid protein expressed in specific cells of the ovary. Changes in relative amounts of full-length oERB and a deletion isoform in CL occurred during the estrous cycle, suggesting that these two types of ERbeta might regulate estrogen actions during early CL development in sheep.

Amino Acid Sequence↗
PubMed1993

Human ovarian aging and mitochondrial DNA deletion.

The functions of human ovary change dynamically around the menopausal period. A decrease of the number of primordial follicles and an increase of fibrous tissues are observed histologically in the aged ovary. As endocrinological aspects at menopause, the synthesis and secretion of ovarian steroid hormones such as estrogens and progesterone decrease, followed with the resultant increases of pituitary gonadotropins. However, the mechanism of menopause and ovarian aging is not well understood. Thus, to study the regulatory mechanism of ovarian dysfunction by aging, we analyzed the accumulation of mitochondrial DNA (mtDNA) mutation in the human ovary in women of various ages. The amplification of a 5.5-kb region in mtDNA with polymerase chain reaction revealed a 0.5-kb band in ovarian samples obtained from menopausal and postmenopausal women, which means that the 5.0-kb deletion of mtDNA in ovarian tissue starts at the menopausal period. The close relationship between the occurrence of ovarian mtDNA deletion and the menstrual irregularity was also observed. These observations suggest that the accumulation of the deleted mtDNA may be a regulating factor of dysfunction of the ovary by aging.

Adult↗
PubMed1994

Growth hormone stimulates follicular development by stimulating ovarian production of insulin-like growth factor-I.

The present study was undertaken to investigate the effects of GH on follicular growth, oocyte maturation, ovulation, and production of insulin-like growth factor-I (IGF-I) in the in vitro perfused rabbit ovaries. Ovulation did not occur in any ovaries perfused with GH at a concentration of 1, 10, 100, or 200 ng/ml, but the addition of GH to the perfusate increased the follicle diameter in a dose-dependent manner. The production of IGF-I by ovaries perfused with medium alone was very low throughout the perfusion period. The addition of 100 ng/ml GH to the perfusate significantly increased ovarian production of IGF-I at 4, 6, 8, and 12 h compared with the contralateral control ovaries. Changes in the tissue concentrations of IGF-I in ovaries perfused with 100 ng/ml GH paralleled those triggered by exposure to 50 IU human CG (hCG). When the effect of GH on the tissue concentration of IGF-I was determined at 4 h, GH stimulated the tissue concentration of IGF-I in perfused rabbit ovaries in a dose-dependent manner. The percent increase in follicle diameter in ovaries treated with GH was significantly correlated with the intraovarian IGF-I content. The mean number of ovulations per ovary and the ovulatory efficiency were significantly reduced in ovaries perfused with 5 IU hCG, compared with those in ovaries perfused with 50 IU hCG. The addition of 100 ng/ml GH to the perfusate significantly increased the ovulatory efficiency and follicle diameter in the 5 IU hCG-treated ovaries. Exposure to GH significantly stimulated the resumption of meiosis in the follicular oocytes compared with that in ovaries perfused with medium alone. Furthermore, GH significantly stimulated the resumption of meiosis in ovulated ova and follicular oocytes in ovaries treated with 5 IU hCG. Thus, exposure to GH-stimulated follicular growth, oocyte maturation, and production of IGF-I in the in vitro perfused rabbit ovaries, which indicates that the ovary is in fact a site of GH reception and action. Additionally, GH enhanced the effects of gonadotropins, acting synergistically to promote the ovulatory process. These observations suggest that GH may amplify gonadotropin actions in the process of follicular development and ovulation, at least in part, by stimulating ovarian IGF-I production.

Animals↗
PubMed1990

[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.

Animals↗