GnRH and Its Mechanism of Action

Braden, Tim D.; Conn, P. Michael

doi:10.1007/978-1-4613-9260-6_2

Cited by 7 publications

(8 citation statements)

References 160 publications

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“…The bioavailability of both 17-b-estradiol and testosterone is therefore widely reduced after the dietary intake of phytoestrogens such as verbascoside. The synthesis of estradiol is carried by the enzyme aromatase and regulated by negative feedback by estradiol itself, which inhibits pituitary FSH secretion by regulating GnRH and its receptor levels at the hypothalamus-pituitary level (Conn 1994;Braden and Conn 1993;Marshall et al 1983). Several studies have demonstrated the ability of exogenous estrogens to suppress FSH and LH levels during the follicular phase of the menstrual cycle (Tsai and Yen 1971;Monroe et al 1972;Young and Jaffe 1976;Messinis and Templeton 1990).…”

Section: Discussionmentioning

confidence: 98%

Phytoestrogens enhance antioxidant enzymes after swimming exercise and modulate sex hormone plasma levels in female swimmers

et al. 2011

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Our aim was to investigate the effects of diet supplementation with phytoestrogens on sex hormone levels, antioxidant adaptive responses and oxidative damage induced by exercise. Ten female swimmers participated for 26 days in a diet intervention with either a functional beverage rich in vitamins C and E or the same beverage but also supplemented with Lippia citriodora extract (PLX) containing 20 mg/100 ml verbascoside. After the intervention all subjects participated in a swimming session for 30 min maintaining the intensity at about 75-80% of their individual best performance time for a 50-m swim. In lymphocytes, the superoxide dismutase activity increased after exercise, with a higher increase in the PLX group. Swimming increased the erythrocyte activity of glutathione peroxidase and glutathione reductase in the PLX group. Purified glutathione reductase activity increased after an in vitro incubation with PLX. No effects were observed on the lymphocyte levels of malondialdehyde and carbonyls, but exercise increased the percentage of high-damaged lymphocytes 2.8 times in the placebo group and 1.5 times in the PLX group. PLX decreased the levels of 17-β-estradiol and testosterone and increased the levels of the sex hormone binding globulin. In conclusion, supplementation with phytoestrogens enhances the glutathione-dependent enzyme activities in erythrocytes and the superoxide dismutase activity in lymphocytes in response to exercise. PLX also shows direct antioxidant properties, by increasing glutathione reductase enzyme activity in vitro. Supplementation with phytoestrogens also decreases the plasma steroid hormone levels, pointing towards a possible agonistic effect of verbascoside in the hypothalamic regulation of estradiol synthesis.

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Section: Discussionmentioning

confidence: 98%

Phytoestrogens enhance antioxidant enzymes after swimming exercise and modulate sex hormone plasma levels in female swimmers

et al. 2011

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“…The synthesis of estradiol is carried by the enzyme aromatase and regulated by negativefeedback by estradiol itself, which inhibits pituitary FSH secretion by regulating GnRH and its receptor levels at the hypothalamus-pituitary level [21][22][23] .…”

Section: Discussionmentioning

confidence: 99%

Kadın Ordu Çalışanlarında Egzersizin Endorfin ve Folikül Uyarıcı Hormon Düzeylerine Etkileri

Ruqaiyah¹,

Ratnawati²,

Mustofa³

2014

Cukurova Medical Journal

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Purpose: This study aimed to investigate whether chronically high-intensity exercise can change β-endorphin and FSH level among female army officer. Material and Methods: Fourty six healthy female army officer volunteered for the study. All of them gave written consent regarding their participation. The subjects were categorized in two groups: high-intensity exercise (HE, 23 subjects) and non exercise (NE, 23 subjects). The inclusion criteria were amenorrhea, no consumption of reproductive hormonal, age between 21-40 years, and not involved in diet programme, while the exclusion criteria were any factors that could interfere with normality. High intensity-exercise was performed chronically by running for between 1953-3200 meter, three times per day, 6 days per weeks, for 7 months. Serum β-endorphin was measured immunoenzymatically using an ELISA method. FSH serum was measured by chemiluminescence method. Results: Age, body weight, height and onset of menarchee were not significantly different between group (P > 0.05).High-intensity exercise significantly increase the β-endorphin level compared to the control (P < 0.01). The level of FSH significantly decrease in the HE group than that the NE group (P < 0.01). Conclusion:In conclusion, the high-intensitiy exercise on among female army officer can increase β-endorphin and decrease follicle stimulating hormone level. Keywords:Performance; gonadotropin; corticotropin; chronic exercise; amenorrhea. ÖZETAmaç: Bu çalışmanın amacı yüksek yoğunlukta egzersizin kadın subaylarda β-endorfin ve FSH düzeylerinde değişikliğe yol açıp açmayacağını belirlemektir. Materyal ve Metod: Kırk altı sağlıklı kadın subay bu çalışma için gönüllü oldu. Bunların hepsi çalışmaya katıldıklarına ilişkin yazılı onay verdi. Denekler 2 grupta kategorize edildi; yüksek yoğunluklu egzersiz grubu (HE, 23 denek) ve egzersiz olmayan grup (NE, 23 denek). Çalışmaya katılım kriterleri; amenore, reprodüktif hormonların tüketilmemesi, yaş aralığı 21-40 ve diyet programının dahil olmaması, bu belirtilen ile uyumsuz bulgular ise çalışma dışı bırakılma kriterleri olarak tanımlandı. Yüksek yoğunluklu egzersiz 7 ay boyunca haftada 6 gün ve günde 3 defa 1953-3200 metre koşu şeklinde uygulandı. Serum β-endorfin düzeyleri immünoenzimatik eliza yöntemiyle ölçüldü. Serum FSH seviyeleri kemiluminosens metoduyla ölçüldü. Bulgular: Yaş, boy uzunluğu, vücut ağırlığı ve menarş başlangıcı bakımından gruplar arasında önemli bir farklılık (p>0.05) gözlemlenmedi. Kontrol grubuyla kıyaslandığında yüksek yoğunluklu egzersiz yapan grupta β-endorfin düzeyleri önemli ölçüde artmıştır (p<0.01). FSH değerleri NE grubuna göre HE grubunda önemli derecede azalmıştır (p<0,01). Araştırma Makalesi / Research Article 496Ruqaiyah et al. Cukurova Medical JournalTartışma: Sonuç olarak yüksek yoğunluklu egzersiz kadın subaylarda β-endorfin düzeylerinin artmasına, FSH düzeylerinin de azalmasına neden olmaktadır.

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“…GnRH-I has been shown to exert biphasic effects on GnRH-I secretion from immortalized and normal hypothalamic neurons, depending on the concentration and duration of treatment (18,28). As well, it has been well documented that GnRH-binding sites are both upand down-regulated by GnRH-I in the pituitary of various species (1,21). As well, it has been well documented that GnRH-binding sites are both upand down-regulated by GnRH-I in the pituitary of various species (1,21).…”

Section: Discussionmentioning

confidence: 99%

“…The treatment of GT1-7 neurons with human CG (hCG) resulted in a dose-and time-dependent decrease in the steady-state GnRH-I (20). It is well documented that the number and messenger RNA (mRNA) levels of GnRHR are both up-and down-regulated by its homologous ligand in the pituitary and ovary (1,12,13,21). In addition to their own ligand, gonadotropins have been shown to regulate the levels of GnRHR mRNA in the ovary (12,14).…”

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confidence: 99%

Differential Regulation of Two Forms of Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid in Human Granulosa-Luteal Cells**This work was supported by grants from the Medical Research Council of Canada.

et al. 2001

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Until recently, the primate brain was thought to contain only one form of GnRH known as mammalian GnRH (GnRH-I). The recent cloning of a second form of GnRH (GnRH-II) with characteristics of chicken GnRH-II in the primate brain has prompted a reevaluation of the role of GnRH in reproductive functions. In the present study, we investigated the hormonal regulation of GnRH-II messenger RNA (mRNA) and its functional role in the human granulosa-luteal cells (hGLCs), and we provided novel evidence for differential hormonal regulation of GnRH-II vs. GnRH-I mRNA expression. Human GLCs were treated with various concentrations of GnRH-II, GnRH-II agonist (GnRH-II-a), or GnRH-I agonist (GnRH-I-a; leuprolide) in the absence or presence of FSH or human CG (hCG). The expression levels of GnRH-II, GnRH-I, and GnRH receptor (GnRHR) mRNA were investigated using semiquantitative or competitive RT-PCR. A significant decrease in GnRH-II and GnRHR mRNA levels was observed in cells treated with GnRH-II or GnRH-II-a. In contrast, GnRH-I-a revealed a biphasic effect (up- and down-regulation) of GnRH-I and GnRHR mRNA, suggesting that GnRH-I and GnRH-II may differentially regulate GnRHR and their ligands (GnRH-I and GnRH-II). Treatment with FSH or hCG increased GnRH-II mRNA levels but decreased GnRH-I mRNA levels, further indicating that GnRH-I and GnRH-II mRNA levels are differentially regulated. To investigate the physiological role of GnRH-II, hGLCs were treated with GnRH-II or GnRH-II-a in the presence or absence of hCG, for 24 h, and progesterone secretion was measured by RIA. Both GnRH-II and GnRH-II-a inhibited basal and hCG-stimulated progesterone secretion, effects which were similar to the effects of GnRH-I treatment on ovarian steroidogenesis. Next, hGLCs were treated with various concentrations of GnRH-II, GnRH-II-a, or GnRH-I-a; and the expression levels of FSH receptor and LH receptor were investigated using semiquantitative RT-PCR. A significant down-regulation of FSH receptor and LH receptor was observed in cells treated with GnRH-II, GnRH-II-a, and GnRH-I-a, demonstrating that GnRH-II and GnRH-I may exert their antigonadotropic effect by down-regulating gonadotropin receptors. Interestingly, GnRH-II and GnRH-II-a did not affect basal and hCG-stimulated intracellular cAMP accumulation, suggesting that the antigonadotropic effect of GnRH-II may be independent of modulation of cAMP levels. Taken together, these results suggest that GnRH-II may have biological effects similar to those of GnRH-I but is under differential hormonal regulation in the human ovary.

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GnRH and Its Mechanism of Action

Cited by 7 publications

References 160 publications

Phytoestrogens enhance antioxidant enzymes after swimming exercise and modulate sex hormone plasma levels in female swimmers

Phytoestrogens enhance antioxidant enzymes after swimming exercise and modulate sex hormone plasma levels in female swimmers

Kadın Ordu Çalışanlarında Egzersizin Endorfin ve Folikül Uyarıcı Hormon Düzeylerine Etkileri

Differential Regulation of Two Forms of Gonadotropin-Releasing Hormone Messenger Ribonucleic Acid in Human Granulosa-Luteal Cells**This work was supported by grants from the Medical Research Council of Canada.

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