Rapid Suppression of Plasma Testosterone Levels and Tumor Growth in the Dunning Rat Model Treated with Degarelix, a New Gonadotropin-Releasing Hormone Antagonist

2006 ◽  
Vol 320 (3) ◽  
pp. 1113-1118 ◽  
Author(s):  
Marc Princivalle ◽  
Pierre Broqua ◽  
Richard White ◽  
Jessica Meyer ◽  
Gaell Mayer ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Rat Model ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Testosterone Levels

scholarly journals Ignoring the challenge? Male black redstarts ( Phoenicurus ochruros ) do not increase testosterone levels during territorial conflicts but they do so in response to gonadotropin-releasing hormone

2011 ◽  
Vol 278 (1722) ◽  
pp. 3233-3242 ◽  
Author(s):  
Beate Apfelbeck ◽  
Wolfgang Goymann
Keyword(s):  
Breeding Season ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Social Challenges ◽  
Testosterone Levels ◽  
Territorial Conflicts ◽  
Territory Defence ◽  
Simulated Territorial Intrusion ◽  
Territorial Intrusion

Competition elevates plasma testosterone in a wide variety of vertebrates, including humans. The ‘challenge hypothesis’ proposes that seasonal peaks in testosterone during breeding are caused by social challenges from other males. However, during experimentally induced male–male conflicts, testosterone increases only in a minority of songbird species tested so far. Why is this so? Comparative evidence suggests that species with a short breeding season may not elevate testosterone levels during territory defence. These species may even be limited in their physiological capability to increase testosterone levels, which can be tested by injecting birds with gonadotropin-releasing hormone (GnRH). We studied two populations of black redstarts that differ in breeding altitude, morphology and the length of their breeding season. Unexpectedly, males of neither population increased testosterone in response to a simulated territorial intrusion, but injections with GnRH resulted in a major elevation of testosterone. Thus, black redstarts would have been capable of mounting a testosterone response during the male–male challenge. Our data show, for the first time, that the absence of an androgen response to male–male challenges is not owing to physiological limitations to increase testosterone. Furthermore, in contrast to comparative evidence between species, populations of black redstarts with a long breeding season do not show the expected elevation in testosterone during male–male challenges.

Relugolix, an oral gonadotropin-releasing hormone antagonist for the treatment of prostate cancer

2021 ◽  
Author(s):  
Daniel J George ◽  
David P Dearnaley
Keyword(s):  
Prostate Cancer ◽  
Advanced Prostate Cancer ◽  
Gnrh Antagonist ◽  
Gonadotropin Releasing Hormone ◽  
Leuprolide Acetate ◽  
Phase Iii ◽  
Major Adverse Cardiovascular Events ◽  
Gnrh Analogues ◽  
Releasing Hormone ◽  
Testosterone Levels

Androgen deprivation therapy using gonadotropin-releasing hormone (GnRH) analogues is standard treatment for intermediate and advanced prostate cancer. GnRH agonist therapy results in an initial testosterone flare, and increased metabolic and cardiovascular risks. The GnRH antagonist relugolix is able to reduce serum testosterone levels in men with prostate cancer without inducing testosterone flare. In the HERO Phase III trial, relugolix was superior to leuprolide acetate at rapidly reducing testosterone and continuously suppressing testosterone, with faster post-treatment recovery of testosterone levels. Relugolix was associated with a 54% lower incidence of major adverse cardiovascular events than leuprolide acetate. As the first oral GnRH antagonist approved for the treatment of advanced prostate cancer, relugolix offers a new treatment option.

Transcripts of testicular gonadotropin-releasing hormone, steroidogenic enzymes, and intratesticular testosterone levels in infertile men

2008 ◽  
Vol 90 (5) ◽  
pp. 1761-1768 ◽  
Author(s):  
Yung Ming Lin ◽  
Song Ling Poon ◽  
Jung Hye Choi ◽  
Johnny Shinn Nan Lin ◽  
Peter C.K. Leung ◽  
...  
Keyword(s):  
Gonadotropin Releasing Hormone ◽  
Steroidogenic Enzymes ◽  
Releasing Hormone ◽  
Testosterone Levels ◽  
Infertile Men

Gonadotropin-Releasing Hormone and Its Physiological and Pathophysiological Roles in Relation to the Structure and Function of the Gastrointestinal Tract

2016 ◽  
Vol 57 (1-2) ◽  
pp. 22-33 ◽  
Author(s):  
Bodil Ohlsson
Keyword(s):  
Gastrointestinal Tract ◽  
Rat Model ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Enteric Neurons ◽  
Gnrh Analog ◽  
Vitro Fertilization ◽  
Releasing Hormone ◽  
Gnrh Analogs

Background: Gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) are involved in the reproductive cycle and regulate the secretion of sex steroids from the gonads. In mammals, GnRH1 is secreted as a hormone from the hypothalamus, whereas both GnRH1 and GnRH2 are present as neuropeptides in a variety of tissues. This review describes the role of GnRH in the gastrointestinal tract. Summary: GnRH1, GnRH2, and LH receptors in humans and rats, and GnRH receptors in rats, have been described in the gastrointestinal tract, where they affect motility, gastric and hormone secretion, and cell proliferation. GnRH analogs are clinically used in the treatment of sex hormone-dependent diseases, i.e., endometriosis and malignancies, and as pretreatments for in vitro fertilization. Severe gastrointestinal dysmotility has been shown to develop in some women after such treatment, along with a reduction in the number of enteric neurons and autoantibodies against GnRH. Consequently, a rat model of enteric neurodegeneration has been developed based on the administration of the GnRH analog buserelin. Serum IgM antibodies against GnRH1, the GnRH2 precursor progonadoliberin-2, and the GnRH receptor have also been described in patients with irritable bowel syndrome and dysmotility, as well as in patients with gastrointestinal disorders associated with diabetes mellitus, posterior laryngitis, and primary Sjögren's syndrome, although no treatments using GnRH analogs have been administered. Conclusion: GnRH and receptors for GnRH and LH are present in the human and rat gastrointestinal tract. Treatment with GnRH analogs may induce severe dysmotility, and a rat model of enteric neurodegeneration has been developed based on stimulation by the GnRH analog buserelin. Autoantibodies against GnRH and its receptor are found in a subgroup of patients with functional bowel disorders and dysmotility, independent of treatment with GnRH analogs.

Pituitary and testicular activity in chickens after embryonic testosterone treatment

1983 ◽  
Vol 244 (1) ◽  
pp. E66-E71
Author(s):  
R. L. Taylor ◽  
B. Glick
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Testosterone Propionate ◽  
Gonadotropin Releasing Hormone ◽  
Testosterone Treatment ◽  
Releasing Hormone ◽  
Testosterone Levels ◽  
32P Uptake ◽  
And Control

This study was conducted to explain the lower circulating testosterone levels in chickens exposed to testosterone propionate (TP) on the 3rd day of incubation. Control and TP males were injected with either luteinizing hormone (LH) or gonadotropin-releasing hormone (GnRH). Testosterone (T), dihydrotestosterone (DHT), and LH were measured by radioimmunoassay. Levels of circulating T in 20-wk-old TP males were significantly lower than controls, but the response to GnRH was similar in both groups. LH levels were also similar. Testosterone responses to LH in 20-wk-old TP males were lower than controls, possibly due to their lower initial T concentrations. Pituitary extracts from TP and control birds showed similar abilities to induce testicular 32P uptake in day-old cockerels. The data demonstrate that the anterior pituitary gland and testes of TP birds are capable of responding to GnRH and LH, respectively. The TP males are defective in that they fail to produce testosterone, which may reflect a reduced concentration of LH receptors in their testes.

Plasma Testosterone Concentration Predicts the Ovulatory Response of Coho Salmon (Oncorhynchus kisutch) to Gonadotropin-Releasing Hormone Analog

1987 ◽  
Vol 44 (7) ◽  
pp. 1351-1357 ◽  
Author(s):  
Martin S. Fitzpatrick ◽  
J. Michael Redding ◽  
Frank D. Ratti ◽  
Carl B. Schreck
Keyword(s):  
Coho Salmon ◽  
Plasma Concentrations ◽  
Oncorhynchus Kisutch ◽  
Gonadotropin Releasing Hormone ◽  
Plasma Testosterone ◽  
Releasing Hormone ◽  
Hormone Analog ◽  
Before And After ◽  
The Mean ◽  
Estradiol 17Β

Plasma concentrations of testosterone, 17α-hydroxy-20β-dihydroprogesterone (DHP), and estradiol-17β were determined in hatchery populations of adult female coho salmon (Oncorhynchus kisutch) before and after the fish were injected with gonadotropin-releasing hormone analog (GnRHa) to accelerate ovulation. Treatment with GnRHa significantly accelerated maturation over that observed in saline-injected controls; however, a number of females that received GnRHa did not ovulate for as long as 8 wk after treatment. Before treatment, the mean plasma levels of DHP did not differ between early- and late-ovulating females; estradiol differed sometimes, but not always; and testosterone was always higher in the early-ovulating fish. Thus, plasma concentrations of testosterone appear to be useful for predicting the sensitivity of coho salmon to GnRHa treatment for induced ovulation.

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