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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gonadal steroids are important hormonal signals that regulate the activity of LHRH synthesizing and releasing neurons. Aside from a direct effect through the feedback mechanisms exerted at hypothalamic and/or anterior pituitary level, gonadal steroids may modify the rhythmic LHRH release by modulating other systems affecting LHRH neurons. 1. In ovariectomized E2-treated female rats, progesterone is able to evoke LHRH release from the perifused hypothalamus without affecting LH and FSH release. 2. Excitatory amino acids (EAA) and their related analogs (NMDA and kainate) are known to stimulate LH release in young rats. When tested in a perifusion system on hypothalamic and anterior pituitary tissues, they differentially stimulate the release of LHRH (NMDA) and of LH (KA); their effect on both structures is markedly reduced following orchidectomy. It appears that gonadal steroids might exert a facilitatory action on the neurosecretory activity of LHRH neurons as well as a modulatory influence on the effect of EAA.
J Steroid Biochem Mol Biol 1991
PMID:Sex steroids and the control of LHRH secretion. 195 16

The mechanism through which chronic stress inhibits the hypothalamic-pituitary-testicular axis has been investigated. Chronic restraint stress decreases testosterone secretion, an effect that is associated with a decrease in plasma gonadotropin levels. In chronically stressed rats there was a decrease in hypothalamic luteinizing hormone-releasing hormone (LHRH) content and the response on plasma gonadotropins to LHRH administration was enhanced. Thus the inhibitory effect of chronic stress on plasma LH and FSH levels seems not to be due to a reduction in pituitary responsiveness to LHRH, but rather to a modification in LHRH secretion. It has been suggested that beta-endorphin might interfere with hypothalamic LHRH secretion during stress. Chronic immobilization did not modify hypothalamic beta-endorphin, while an increase in pituitary beta-endorphin secretion was observed. Since we cannot exclude that changes in beta-endorphin secreted by the pituitary or other opioids may play some role in the stress-induced decrease in LHRH secretion, the effect of naltrexone administration on plasma gonadotropin was studied in chronically stressed rats. Naltrexone treatment did not modify the decrease in plasma concentrations of LH or FSH. These findings suggest that the inhibitory effect of restraint on the testicular axis is exerted at hypothalamic level by some mechanism other than opioids.
J Steroid Biochem Mol Biol 1991
PMID:Stress induced changes in testis function. 195 48

The biosynthesis and intracellular processing of the polypeptide precursor of the beta A-chain of the fertility hormone inhibin were assessed by infecting a wide spectrum of cell types with a recombinant vaccinia virus. Most cell lines, including follicular granulosa cells, secrete both prohormone and mature hormone as homodimers (activin) composed of disulfide-linked subunits of 54 kDa (proactivin-A) and 14 kDa (activin-A), respectively, and a small amount of prohormone-mature hormone heterodimers. Mature activin is secreted from mouse pituitary cells (AtT-20), while pig kidney cells [PK(15)] secrete mostly proactivin. More prohormone is secreted in the presence of NH4Cl, suggesting that prohormone processing is facilitated by low pH. Proactivin-A is not a ligand for the mannose-6-phosphate/insulin growth factor-II receptor. The recombinant activin stimulates FSH release from pituitary cells and differentiates erythroleukemia cell lines in vitro.
Mol Endocrinol 1990 Aug
PMID:Expression and processing of the activin-A/erythroid differentiation factor precursor: a member of the transforming growth factor-beta superfamily. 196 71

Regulation by PRL of aromatase (P450arom) mRNA and protein and estradiol (E) biosynthesis was examined in granulosa cells during early stages of luteinization in vitro and in vivo. PRL caused a dose-dependent (10-1000 ng/ml) decrease in P450arom mRNA and E biosynthesis (greater than 99%) in luteinized rat granulosa cells in vitro, even when the cells were cultured in the presence of insulin and hydrocortisone (hormones known to synergize with PRL to induce proteins in mammary tissue) or in the presence of forskolin (a nonhormonal stimulator of cAMP). PRL also prevented the marked increases in aromatase mRNA and E biosynthesis stimulated by FSH and forskolin in nonluteinized preovulatory granulosa cells in culture. These effects of PRL on granulosa cells in culture were specific for aromatase and were not observed for other proteins, such as cholesterol side-chain cleavage cytochrome P450 (P450scc) and alpha 2-macroglobulin. PRL also decreased P450arom mRNA and protein during the early stages of luteinization in vivo. PRL administered to rats beginning day 1 postovulation to mimic hormone release during pseudopregnancy reduced the progressive increase in P450arom mRNA occurring in corpora lutea on days 3-4 in ovulated rats not treated with PRL. CB 154, a dopamine agonist that inhibits pituitary release of PRL, caused P450arom mRNA and protein to decrease 50% if given to pregnant rats on days 8-10 of gestation, but increased P450arom mRNA and protein if given to pregnant rats on days 10-12 of gestation. These diverse effects of PRL in pregnancy suggest that placental factors may modify the response of luteal cells to PRL during gestation.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1990 Jan
PMID:Regulation of aromatase mRNA and estradiol biosynthesis in rat ovarian granulosa and luteal cells by prolactin. 197 Jan 19

A cDNA probe for the beta subunit of bovine FSH (FSH-beta) detects multiple restriction fragment length polymorphisms (RFLPs) in sheep genomic DNA consistent with an insertion/deletion polymorphism around the FSH-beta locus. The presence of the insertion/deletion was confirmed by screening over 100 individuals with two restriction enzymes detecting RFLPs. All individuals showed the same patterns of fragments with both enzymes. A partial restriction map of the FSH-beta gene in sheep suggests that the insertion/deletion is approximately 2 kb in size and located downstream from the third exon. Individual DNA samples were analysed from two flocks where the Booroola F gene is known to be segregating. Individuals that were heterozygous for the F gene were shown to be homozygous for one or other of the two alleles. Genetic recombination between the FSH-beta locus and the F gene was observed in four pedigrees and there was no evidence that the insertion/deletion is closely linked genetically to the Booroola F gene. A major gene transcript of 2.2-2.3 kb was detected on Northern blots of sheep RNA. Neither the insertion/deletion polymorphism nor the presence of the F gene appeared to influence the size of the FSH-beta gene transcript.
J Mol Endocrinol 1990 Oct
PMID:The Booroola F gene mutation in sheep is not located close to the FSH-beta gene. 197 99

These studies were conducted to examine activation of in vitro-matured porcine oocytes in response to an electrical stimulus or to an ionophore. Cumulus-enclosed porcine oocytes were incubated in maturation medium supplemented with either FSH and LH (MM:Exp.1) or pregnant mare serum gonadotropin (PMSG; MM-P: experiments 2-4) at 39 degrees C in 5% CO2:95% air with high humidity. In experiment 1, groups of oocytes were stripped of cumulus and then shampulsed (control) or electrically pulsed with a Zimmerman Cell Fusion unit at 24, 31, 41, 48, and 65 h of incubation. Control oocytes were exposed to the activation medium for 20 sec, whereas oocytes to be pulsed were subjected to a single activation pulse (120 V, 30 microseconds). Oocytes were cultured for an additional 24 h and then fixed and examined. For oocytes pulsed at 24, 31, 41, 48, and 65 h, the proportions which activated were 0, 0, 87, 88, and 83%, respectively. In experiment 2, oocytes were electrically or sham-pulsed with a BTX 200 Embryomanipulation System at 24, 30, and 40 h of incubation and respective proportions of oocytes activating were 27%, 39%, and 72%. In experiment 3, oocytes were subjected to 0, 1, or 2 activation pulses after 41 h of incubation in MM-P. Double-pulsing halved the proportion of activated oocytes (P less than .0001). In experiment 4, oocytes were subjected to 0, 25, 50, or 100 microM ionophore at 48 h of incubation. Proportions of oocytes activated by ionophore were greater than for control (P less than .05), but activation was not increased by increasing dose of ionophore.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1991 Jan
PMID:Response of porcine oocytes to electrical and chemical activation during maturation in vitro. 199 82

The regulation of the production of steroids and steroid sulfates and the activity of aromatase in human luteinized granulosa cells were investigated. The cells were cultured for 48 h in the presence or absence of hCG and FSH. Basal production of pregnenolone (Pre, 0.3 +/- 0.03 ng/micrograms protein) and progesterone (P, 19.3 +/- 1.7 ng/micrograms protein) were high compared with that of other steroids beyond P in the steroidogenic pathway. The concentration of 17 alpha-hydroxyprogesterone (17-OHP) was lower 0.17 +/- 0.06 ng/micrograms and that of other steroids in the 4-ene and 5-ene pathways and steroid sulfates less than 0.05 ng/micrograms. Both hCG and FSH (100 ng/ml) stimulated the production of Pre and P 3- to 5-fold, but only minimal stimulation of other steroids and steroid sulfates was observed. Aromatase activity of granulosa-luteal cells was measured from the rate of formation of 3H2O from 1 beta-[3H]androstenedione (1 beta[3H]A) after exposing the cells to hCG, FSH or estradiol (E2) for 48 h. Basal aromatase activity was relatively low, but hCG and FSH stimulated aromatase 8- and 4-fold, respectively. The incubation of granulosa-luteal cells with E2 did not affect basal aromatase activity, but E2 augmented FSH-stimulated aromatase 1.4-fold (P less than 0.025). The results suggest that there is low 17 alpha-hydroxylase and steroid sulfokinase activity in human granulosa-luteal cells. Aromatase activity in these cells is regulated by both hCG and FSH, and intra-ovarian estrogens may regulate granulosa cell aromatase activity.
J Steroid Biochem Mol Biol 1991 Jul
PMID:Regulation of steroid and steroid sulfate production and aromatase activity in cultured human granulosa-luteal cells. 206 61

In order to better understand the role of FSH in reproduction, we have studied the expression of its receptor in the male rat. A DNA probe for the rat FSH receptor (FSHR) was generated by the polymerase chain reaction, and a partial genomic clone was isolated. Northern blot analysis revealed two transcripts for the FSHR, a 2.6-kilobase (kb) transcript, which is the predominant mRNA, and a 4.5-kb transcript. The two transcripts were specific to the testis and ovary, and in the testis, the expression of the mRNA appeared to be primarily in the Sertoli cells. Northern blot analysis showed the presence of FSHR mRNA in testes from rats ranging in age from 10-60 days as well as in Sertoli cells cultured from 20-day-old and adult animals. FSHR mRNA levels in testes synchronized to specific stages of the seminiferous epithelium were shown by Northern blot analysis to be highest in stages XIII-II and to decrease to a minimum at stages VII-VIII. The levels of FSHR mRNA underwent more than a 3-fold change during the cycle of the seminiferous epithelium.
Mol Endocrinol 1991 May
PMID:Expression of follicle-stimulating hormone receptor mRNA in rat testes and Sertoli cells. 207 27

Tissue-type plasminogen activator (tPA) is secreted by rat granulosa cells in response to treatment with activators of protein kinase A (follitropin, FSH), protein kinase C (gonadotropin-releasing hormone, GnRH) and tyrosine kinase (epidermal growth factor, EGF). Because steroid hormones have been shown to enhance the gonadotropin stimulation of ovarian differentiation, we investigated the effects of steroid hormones, alone or together with various kinase activators, on tPA activities and mRNA levels in cultured rat granulosa cells. Treatment of cells with dexamethasone (DEX; a glucocorticoid agonist) or R1881 (an androgen agonist) caused an increase in tPA secretion and mRNA levels. In addition, the stimulation of tPA activity and mRNA levels by FSH (50 ng/ml) was synergistically enhanced by cotreatment with DEX or R1881 in a time-dependent manner with 2.8- and 1.6-fold increase at 9 h after incubation as compared to cells treated with FSH alone. In contrast, treatment with diethylstilbestrol had no effect on tPA levels. Furthermore, tPA activity and mRNA levels induced by GnRH and EGF were also increased by cotreatment with DEX or R1881 as compared with cells treated with GnRH or EGF alone. Likewise, the stimulation of tPA mRNA levels by dibutyryl cAMP, a protein kinase A activator, and phorbol myristate acetate (PMA), a protein kinase C activator, was enhanced by cotreatment with DEX or R1881. These results demonstrate that glucocorticoid and androgen enhance tPA secretion and mRNA levels stimulated by FSH, GnRH and EGF in granulosa cells. The rat granulosa cells provide a useful model for studying the mechanism of regulation of tPA gene expression by steroid hormones.
Mol Cell Endocrinol 1990 Jan 22
PMID:Synergistic effect of glucocorticoids and androgens on the hormonal induction of tissue plasminogen activator activity and messenger ribonucleic acid levels in granulosa cells. 210 7

FSH plays an important role in testicular Sertoli cell differentiation and function in spermatogenesis. Previous studies using rat androgen-binding protein (ABP) as a marker of FSH action on Sertoli cells have demonstrated in vivo and in vitro regulation of ABP. We now have extended these studies to examine FSH regulation of ABP mRNA using Northern blot hybridization. In the immature rat testicular ABP mRNA [1.7- and 2.3-kilobase (kb) species] increased with age and reached a maximum 20 days postpartum, coincident with an increased plasma FSH concentration. To determine the direct effect of FSH on Sertoli cells, we examined ABP mRNA in vitro. In Sertoli cell-enriched cultures FSH was found to maintain the major 1.7-kb ABP RNA transcript level over 5 days of treatment in a dose-dependent manner, whereas in the absence of FSH, ABP mRNA declined with time in culture. The ABP mRNA maintenance by FSH was accompanied by higher concentrations of secreted immunoreactive ABP, which declined in the absence of FSH. This FSH effect on ABP mRNA and secreted ABP was mimicked by the cAMP analog (Bu)2cAMP. After the decline of ABP mRNA during culture, administration of FSH did not result in a detectable increase in the 1.7-kb ABP mRNA within 3 days, whereas cAMP and c-fos mRNA were rapidly induced within 15 min. On the contrary, the level of the minor hybridizing ABP mRNA (2.3 kb) was altered by FSH, indicating differential regulation of the 1.7- and 2.3-kb hybridizing species. Also, after FSH deprivation, tissue plasminogen activator and inhibin alpha mRNA were substantially increased within 6 h of FSH treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1990 Feb
PMID:Follicle-stimulating hormone regulation of androgen-binding protein messenger RNA in sertoli cell cultures. 210 26


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