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Query: UNIPROT:P06889 (Mol)
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Objectives of the present research were to determine the influences of types of media, sera, time and hormones on equine oocyte in vitro maturation (IVM). The following types of media and sera were evaluated: Menezo's B2 medium (B2), modified Tissue Culture Medium 199 (TCM), Defined Medium (DM), fetal calf serum (FCS), mare serum collected on the first day of estrus (MS), and mare serum collected on the day of ovulation (MSO). Resultant oocyte maturation was compared with the control: DM with bovine serum albumin (BSA). Effect of culture time (0, 15, and 32 hr) and the following hormones on oocyte IVM were evaluated: none, bovine luteinizing hormone (bLH; 1, 10, 100 micrograms/ml), equine luteinizing hormone (eLH; 100 micrograms/ml), bovine follicle-stimulating hormone (FSH; 5 micrograms/ml), and equine chorionic gonadotropin (eCG; 1 and 100 IU/ml). Cumulus expansion in the media and sera experiments was 50% (DM with BSA), 80% (TCM, B2, and DM with MS or MSO), and 100% (FCS with any medium). The proportion of metaphase II (MII) oocytes was significantly (P less than 0.05) increased the percentage of MII oocytes as compared with 0 hr of culture. Cumulus expansion in the hormone experiments was 80% (none, bLH, and eLH), and 100% (eCG and FSH). Freshly prepared bLH significantly (P less than 0.05) inhibited nuclear maturation of equine oocytes. In summary, 15 hr of culture was sufficient time for equine oocyte IVM and all combinations of medium, serum, and hormone addition were equally effective in achieving IVM except fresh bLH and DM with BSA.
Mol Reprod Dev 1991 Dec
PMID:Equine oocyte in vitro maturation: influences of sera, time, and hormones. 175 Oct 41

Synthetic peptides corresponding to discontinuous segments of the hFSH-beta subunit, amino acids 33-53 and 81-95, have been shown to interact with the follicle-stimulating hormone (FSH) receptor. In this study, we demonstrate that hFSH-beta-(33-53)-(81-95)-peptide amide, a synthetic peptide encompassing these binding regions, possesses higher affinity for the FSH receptor than either synthetic hFSH-beta-(33-53) or hFSH-beta-(81-95). This increased affinity suggests that each binding component is effectively interacting with the receptor, providing evidence that these two separate receptor binding regions of hFSH-beta form a continuous binding surface on the native molecule. These results also suggest that binding surfaces of very complex proteins, such as the heterodimeric glycoprotein hormone FSH, may be mimicked by a linear arrangement of its binding domains. A model based on energetics of the peptide-receptor interaction is also described. The results indicate that the affinity (Ka) of a peptide containing different binding domains can be approximated utilizing the product of the affinity constant of each binding domain (Ka = k1.k2...kn).
Mol Cell Endocrinol 1991 Jul
PMID:A synthetic peptide encompassing two discontinuous regions of hFSH-beta subunit mimics the receptor binding surface of the hormone. 177 4

To find out the local regulation of inhibin production and its possible paracrine role in the seminiferous epithelium, inhibin alpha mRNA levels were measured in sequential 1 mm segments of rat seminiferous tubules accurately staged by transillumination technique. Highest levels were found at stages XIV-I-IV of the cycle, and lowest at stages VI-VIIb of the cycle. When dividing spermatogonia were selectively destroyed by 3 Gy of high-energy X-irradiation, stage-specific inhibin alpha mRNA levels remained unchanged until 26 and 38 days after irradiation when stages VII and VIII of the cycle showed 6- and 4-fold increases during a selective reduction of pachytene spermatocyte and round spermatid numbers, respectively. The results suggest that these cells at a strictly stage-specific fashion have a paracrine inhibitory effect on Sertoli cell inhibin alpha gene expression. Inhibin alpha mRNA level also correlates closely to the follicle-stimulating hormone-stimulated cAMP production during the cycle of the seminiferous epithelium, but does not seem to have a correlation to spermatogonial DNA synthesis.
Mol Cell Endocrinol 1991 Dec
PMID:Stage-specific cellular regulation of inhibin alpha-subunit mRNA expression in the rat seminiferous epithelium. 179 7

To investigate the regulation of the follicle-stimulating hormone (FSH) and luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor genes by gonadotropins, we examined the effect of pregnant mare's serum gonadotropin (PMSG) or PMSG-hCG on the expression of FSH and LH/hCG receptors in rat ovaries. After administration of PMSG, Northern blot analysis using the FSH receptor cDNA probe revealed that a major band of 2400 nucleotides was detected which reached the maximal level on day 3. On the other hand, the level of LH/hCG receptor mRNA, a major mRNA of 5400 nucleotides and minor species of 7500, 3600, 2300 and 1200 nucleotides, increased progressively during 4 days. Treatment with hCG resulted in a decrease of FSH and LH/hCG receptor mRNA levels, and the level of FSH receptor mRNA was completely suppressed. Although the level of LH/hCG receptor mRNA was also suppressed from 3 h to an almost undetectable level at 24 h after hCG injection, it recovered to the control level by 48 h and exceeded this level several fold by 72 h. The reappearance of LH/hCG receptors following desensitization was preceded by an increase in mRNA levels. These studies demonstrate that hormonal regulation of gonadotropin receptor mRNAs on rat ovary reflects the changes in gonadotropin receptor levels.
Mol Cell Endocrinol 1991 Dec
PMID:Hormonal regulation of gonadotropin receptor mRNA in rat ovary during follicular growth and luteinization. 179 13

Effects of recombinant human inhibin (rh inhibin) and testosterone on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion and mRNA levels of gonadotropin subunits were investigated in superfused male rat pituitary cell cultures. During superfusion, the cells were stimulated with gonadotropin-releasing hormone (GnRH) pulses (10 nM, 6 min/h) and exposed to rh inhibin (2 ng/ml) and/or testosterone (10 nM) for up to 20 h. The concentrations of FSH and LH were measured in effluent media by radioimmunoassay (RIA), and subunit mRNAs were determined by Northern blot hybridizations using rat FSH beta, LH beta and alpha genomic and cDNA probes. Rh inhibin suppressed the secretion of FSH (30-40% of control) and the secretion of LH to 50-60% of control, but inhibited only FSH beta mRNA (to non-detectable levels). Testosterone alone suppressed the release of LH to 50% of control, whereas FSH release was increased to 130-160% (P less than 0.05) of control. This increase was due to higher interpulse values without significant changes in the pulse amplitude. Also FSH beta mRNA level was increased (1.5-fold, P less than 0.05) but only after 17-20 h of treatment. On the other hand, testosterone had no effect on LH beta and alpha subunit mRNA levels. Testosterone in combination with rh inhibin showed an inhibitory effect on LH beta mRNA; however, the pattern of LH release was not significantly different from that observed with rh inhibin or testosterone alone. Combined effects of testosterone and rh inhibin on FSH secretion and FSH beta mRNA were similar to those observed with rh inhibin alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1991 Dec
PMID:Effects of recombinant human inhibin and testosterone on gonadotropin secretion and subunit mRNA in superfused male rat pituitary cell cultures stimulated with pulsatile gonadotropin-releasing hormone. 179 14

The effects of angiotensin II on cytosolic free Ca2+ ion concentrations ([Ca2+]i) were studied in single porcine granulosa cells using the calcium-sensitive fluorescent dye fura-2 and high temporal resolution fluorescent videomicroscopy. Angiotensin II initiated specific, rapid, transient and topographically organized increases in [Ca2+]i in a subpopulation of single swine granulosa cells. The Ca2+ source for this angiotensin II-mediated [Ca2+]i transient appeared to be internal stores, and a pertussis toxin-sensitive guanine nucleotide binding protein was implicated in this receptor-mediated Ca2+ rise. Our single-cell studies also revealed a striking functional heterogeneity among granulosa cells, since follicle-stimulating hormone-responsive cells were not angiotensin II responsive. We conclude that single swine granulosa cells are targets of specific angiotensin II action on intracellular pools of Ca2+.
Mol Cell Endocrinol 1991 Oct
PMID:Angiotensin II induces calcium release in a subpopulation of single ovarian (granulosa) cells. 179 80

We have shown previously that activin A increases the number of immunoreactive follicle-stimulating hormone (FSH) cells. To further investigate the action of activin A, we examined its effects on anterior pituitary cells fractionated by centrifugal elutriation. Before activin A treatment, FSH cells were widely distributed among various fractions; a higher proportion of FSH cells was found in larger cell fractions (fractions 5-9), and a lower proportion in smaller cell fractions (fractions 2-4). After culture of the cells in each fraction with activin A (10 ng/ml) for 72 h, the number of FSH cells in fraction 4 only was significantly (P less than 0.05) higher by 225% than that in cells cultured without activin A. The amount of FSH secreted into the medium was minimal or undetectable in fractions 1-4. However, FSH secretion tended to be, or was significantly (P less than 0.01 in fraction 9), stimulated by activin A in fractions 5-9, in which the numbers of FSH cells were not significantly affected. These results suggest a dual mode of action of activin A on FSH: activin A increases the number of FSH cells in a specific type(s) of middle-sized cell fraction, and stimulates FSH secretion at least from larger cells without affecting the number of FSH cells.
Mol Cell Endocrinol 1991 May
PMID:Effects of activin A on anterior pituitary cells fractionated by centrifugal elutriation. 181

Ovine cumulus-enclosed oocytes collected from antral follicles (3-5 mm in diameter) were cultured in vitro with 2 x 10(6) granulosa cells/ml in the presence or absence of gonadotropins or in the presence of cytochalasin D (CD). The maturation rate was assessed after 24 h of culture. In the control group, in the presence of gonadotropins (follicle-stimulating hormone-luteinizing hormone (FSH-LH; -10 micrograms/ml) 100% of the oocytes reached metaphase II. Whereas intercellular junctions were no longer present after 6-7 h of culture, germinal vesicle breakdown (GVBD) occurred by the same time. In contrast, in the absence of gonadotropin, the majority of the oocytes (59%) remained blocked in GV stage. The inhibition exerted by the granulosa cells on meiotic resumption was overcome when the cumulus-oocyte complexes (COCs) were incubated in CD (5 micrograms/ml) for 6 h at the beginning of the culture. Under these conditions, 85% of the oocytes matured with extrusion of the first polar body. Cytological analysis by cytofluorescence (NBD phallacidin) and electron microscopy showed that, after 6 h of treatment, CD provoked a redistribution of the microfilaments, mainly in the cumulus cells and to a lesser extent in the oocyte cortex. Intercellular junctions disappeared concomitantly with a significant decrease of the intercellular transport of tritiated uridine. The initiation of GVBD occurred at the same time. These results indicate that the resumption of meiosis was correlated with a loss of both junctional complexes (intermediate and gap junctions) between the cumulus cells and the oocyte.
Mol Reprod Dev 1991 Jun
PMID:Cytochalasin D treatment induces meiotic resumption in follicular sheep oocytes. 190 84

Oxytocin and its mRNA have been detected in bovine granulosa cells, but the function of follicular oxytocin is not well understood. We have shown previously that oxytocin exerts a specific, dose-dependent, stimulatory effect on progesterone secretion by granulosa, but not theca cells isolated from bovine preovulatory follicles obtained 48 h after the initiation of luteolysis. The objective of the present study was to characterize the development of granulosa cell responsiveness to oxytocin during the follicular phase. Granulosa cells and theca interna were isolated form preovulatory follicles early in the follicular phase (24 h after the initiation of luteolysis) or after the luteinizing hormone (LH) surge and cultured in defined medium for 5 days with or without oxytocin and in the presence or absence of gonadotropins. Granulosa, but not theca cells obtained before the LH surge increased progesterone production 3.3-fold in response to oxytocin. However, late in the follicular phase, after the LH surge, granulosa cells did not respond to oxytocin (or to follicle-stimulating hormone (FSH) or LH). These findings suggest that the LH surge (1) stimulates granulosa cells to maximal progesterone secretion, so that they cannot be further stimulated, (2) abolishes the responsiveness of granulosa cells to oxytocin, or (3) stimulates granulosa cells to increase oxytocin production, so that exogenous oxytocin has no additional effect.
Mol Cell Endocrinol 1991 Jun
PMID:Oxytocin stimulates progesterone production by bovine granulosa cells isolated before, but not after, the luteinizing hormone surge. 193 22

Direct roles of follicle-stimulating hormone (FSH)-suppressing protein (FSP) and activin in regulation of ovarian granulosa cell differentiation have been reported recently. The present study further investigated the effects of these peptides on steroidogenesis and inhibin production as well as cAMP generation in cultured granulosa cells from immature, diethylstilbestrol (DES)-treated rats. In the presence of FSH (20 ng/ml) and activin (30 ng/ml), which enhanced FSH-induced aromatase activity, progesterone production and inhibin production, FSP (1-100 ng/ml) reversed the stimulating activities of activin in a dose-dependent manner. In addition, activin reversed the inhibitory effects of FSP on FSH-induced aromatase activity and inhibin production. In the presence of FSH, activin enhanced FSH-stimulated extracellular cAMP accumulation, and FSP caused a reduction in extracellular cAMP. Activin but not FSP also stimulated basal cAMP level. In the presence of forskolin, a potent stimulant of adenyl cyclase activity which stimulated extracellular cAMP, aromatase activity, progesterone production and inhibin production, activin augmented the effect of forskolin on all four parameters, whereas FSP significantly enhanced progesterone production without changing the other three parameters. Our findings suggest that activin action on rat granulosa cells may be mediated via regulation of cAMP generation. The action of FSP and FSH and/or activin-dependent, consistent with either an action as an activin binding protein or by a direct action of FSP on the granulosa cells.
Mol Cell Endocrinol 1991 Aug
PMID:Interactions between activin and follicle-stimulating hormone-suppressing protein and their mechanisms of action on cultured rat granulosa cells. 193 50


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