RESUMO
The corpus luteum is a temporary endocrine structure in mammals that plays an important role in the female reproductive cycle and is formed from a ruptured and ovulated follicle with rapid angiogenesis. Vascular endothelial growth factor (VEGF) is thought to be vital in normal and abnormal angiogenesis in the ovary, but the molecular regulation of luteal VEGF expression during corpus luteum development in vivo is still poorly understood at present. Therefore, we examined whether hypoxia-inducible factor-1a (HIF-1a) is induced and regulates VEGF expression and luteal function in vivo using a pseudopregnant rat model treated with a small-molecule inhibitor of HIF-1a, echinomycin. Corpus luteum development in the pseudopregnant rat ovary was determined after measuring plasma progesterone concentration and ovarian prostaglandin F2a content to reflect changes in HIF-1a and VEGF on different days of this developmental process. At day 7, the corpus luteum was formed and the expression of HIF- 1a/VEGF reached a maximum, while a significant decrease in HIF-1a/ VEGF expression was observed when luteolysis occurred at day 13. Additionally, echinomycin blocked luteal development by inhibiting VEGF expression mediated by HIF-1a and following luteal function by detecting the progesterone changes at day 7. These results demonstrated that HIF-1a-mediated VEGF expression might be an important mechanism regulating ovarian luteal development in mammals in vivo, which may provide new strategies for fertility control and for treating some types of ovarian dysfunction, such as polycystic ovarian syndrome, ovarian hyperstimulation syndrome, and ovarian neoplasia.
Assuntos
Corpo Lúteo/crescimento & desenvolvimento , Dinoprosta/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Ovário/metabolismo , Progesterona/sangue , Pseudogravidez/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Corpo Lúteo/metabolismo , Manutenção do Corpo Lúteo , Feminino , Regulação da Expressão Gênica , Masculino , Gravidez , Pseudogravidez/sangue , Ratos , Ratos Sprague-Dawley , Transdução de SinaisRESUMO
Progesterone receptor (PR) plays an important role in mammals pregnancy which is characterized by greater progesterone plasma concentrations. We assessed PR protein distribution in the rabbit uterus by immunohistochemistry in two progestational conditions: pseudopregnancy (intact adult animals treated with hCG) and after application of a synthetic progestin, medroxyprogesterone acetate (MPA), to ovariectomized animals (OVX). PR immunoreactivity in uterine epithelium of pseudopregnant rabbits was increased in relation to non-pseudopregnant (NP) rabbits. Amounts were similar on Days 1, 3, and 5 of treatment, and was greater on Day 7 (P<0.001). In contrast, a significant diminution in PR immunoreactivity was observed in stroma cells from Days 1 to 7 (P<0.001). In OVX rabbits treated with MPA, an increase in PR immunoreactivity was observed in the uterine epithelium on Days 1 to 5 of treatment, reaching a maximum on Day 3 (P<0.001). In contrast, in stromal cells a diminution in PR immunoreactivity was observed when compared to the OVX group on Days 1, 3 and 7 of MPA treatment (P<0.001), and there was a slight increase on Day 5. Results suggest a differential time course and tissue specific immunoreactivity for PR in the uterus of the rabbit in two progestational conditions. The present study indicated synthetic progestins have different mechanisms of receptor regulation than those of natural hormones and it should be taken into account in reproductive applications.
Assuntos
Acetato de Medroxiprogesterona/farmacologia , Pseudogravidez/metabolismo , Receptores de Progesterona/metabolismo , Útero/efeitos dos fármacos , Útero/metabolismo , Animais , Gonadotropina Coriônica/farmacologia , Anticoncepcionais/farmacologia , Avaliação Pré-Clínica de Medicamentos , Feminino , Imuno-Histoquímica , Ovariectomia , Progesterona/sangue , Pseudogravidez/sangue , Pseudogravidez/patologia , Coelhos , Fatores de Tempo , Útero/patologiaRESUMO
BACKGROUND: In the rat, the maintenance of gestation is dependent on progesterone production from the corpora lutea (CL), which are under the control of pituitary, decidual and placental hormones. The luteal metabolism of progesterone during gestation has been amply studied. However, the regulation of progesterone synthesis and degradation during pseudopregnancy (PSP), in which the CL are mainly under the control of pituitary prolactin (PRL), is not well known. The objectives of this investigation were: i) to study the luteal metabolism of progesterone during PSP by measuring the activities of the enzymes 3beta-hydroxysteroid dehydrogenase (3betaHSD), involved in progesterone biosynthesis, and that of 20alpha-hydroxysteroid dehydrogenase (20alphaHSD), involved in progesterone catabolism; and ii) to determine the role of decidualization on progesterone metabolism in PSP. METHODS: PSP was induced mechanically at 10:00 h on the estrus of 4-day cycling Wistar rats, and the stimulus for decidualization was provided by scratching the uterus on day 4 of PSP. 3betaHSD and 20alphaHSD activities were measured in the CL isolated from ovaries of PSP rats using a spectrophotometric method. Serum concentrations of progesterone, PRL, androstenedione, and estradiol were measured by radioimmunoassay (RIA). RESULTS: The PSP stage induced mechanically in cycling rats lasted 11.3 +/- 0.09 days (n = 14). Serum progesterone concentration was high until day 10 of PSP, and declined thereafter. Serum PRL concentration was high on the first days of PSP but decreased significantly from days 6 to 9, having minimal values on days 10 and 11. Luteal 3betaHSD activities were elevated until day 6 of PSP, after which they progressively declined, reaching minimal values at the end of PSP. Luteal 20alphaHSD activities were very low until day 9, but abruptly increased at the end of PSP. When the deciduoma was induced by scratching the uterus of pseudopregnant animals on day 4 (PSP+D), PSP was extended to 18 +/- 2.2 days (n = 8). In PSP + D rats, serum progesterone and PRL levels, and luteal 3betaHSD activities were higher than in pseudopregnant rats on day 11. Decidualization also prevented the increase in luteal 20alphaHSD activities observed on day 11 of PSP. Administration of the dopaminergic agonist CB154 in PSP + D rats on day 10 of PSP induced a decline in both serum PRL and progesterone on day 11 of PSP, values that were not different from that of pseudopregnant controls. CONCLUSIONS: We have established that during the final period of PSP a decline in progesterone biosynthesis occurs before the increase in progesterone catabolism. We have also shown that decidualization in pseudopregnant rats extends the life of the CL by prolonging the production of pituitary PRL, and by maintaining high 3betaHSD and low 20alphaHSD activities within the CL leading to sustained production of progesterone.
Assuntos
17-Hidroxiesteroide Desidrogenases/metabolismo , 20-Hidroxiesteroide Desidrogenases/metabolismo , Corpo Lúteo/enzimologia , Deciduoma/fisiologia , Pseudogravidez/enzimologia , 17-Hidroxiesteroide Desidrogenases/sangue , 20-Hidroxiesteroide Desidrogenases/sangue , Androstenodiona/sangue , Animais , Bromocriptina/farmacologia , Dopamina/metabolismo , Estradiol/sangue , Feminino , Fase Luteal/sangue , Fase Luteal/fisiologia , Progesterona/biossíntese , Progesterona/sangue , Prolactina/biossíntese , Prolactina/sangue , Pseudogravidez/sangue , Ratos , Ratos WistarRESUMO
Different molecular forms of circulating prolactin (PRL) are known to occur in several species. As no such information was available in dogs, we assessed the molecular profile of circulating PRL in bitches. Pooled sera from covertly (CTRL) and overtly pseudopregnant (PSPT) diestrous bitches with high or low (> 10 or < 10 ng x mL(-1), respectively) serum PRL (measured by ELISA) were analyzed by Sephadex G-100 and Concanavalin A-Sepharose column chromatography. Four serum PRL fractions were identified and termed big-big, big (> 67 kDa), native (23 kDa) and fragmented (< 20) kDa) PRL. The percentages of these fractions were roughly similar in CTRL and PSPT animals, irrespective of their serum PRL levels (higher in PSPT than in CTRL bitches). A large proportion of glycosylated PRL (between 69 and 100%) was also detected in these sera. We conclude that in dogs, circulating PRL occurs in multiple molecular forms, whose relative abundance is comparable in covertly and overtly pseudopregnant bitches.
Assuntos
Cães/sangue , Prolactina/sangue , Pseudogravidez/veterinária , Animais , Cromatografia em Gel/veterinária , Diestro/sangue , Cães/fisiologia , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Glicosilação , Prolactina/química , Pseudogravidez/sangueRESUMO
Hormonal and clinical evaluation was performed in eleven females with diagnosis of pseudocyesis. Plasma levels of pituitary gonadotropins (FSH-LH), progesterone, estradiol and thyroid hormones (T3, T4, TSH) under basal conditions were measured through radioimmunoassay. Diagnosis of pseudocyesis was made according to the following criteria: a) secondary amenorrhea (greater than 12 weeks); b) two or more symptoms of gestation; c) conviction of being pregnant; d) negative HCG or pelvic ultrasound study. The circulation levels of gonadotropins were within normal limits. Progesterone exhibited a ovulatory pattern and thyroid hormones were normal for every instance. Once case had slight hyperprolactinemia (26.0 ng/ml) with impaired gonadotropin production and ovulatory progesterone. All patients had galactorrhea. The psychological study disclosed a tendency toward depression. Our findings partially confirmed previous observations, differing basically on that we observed normal hormonal trend.