Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Study Confirms Process Leading To Disorder Causing Male Characteristics In Women

22.06.2004


Ovarian stimulation of male steroids is the culprit behind this disorder.

A woman finds herself with excessive facial hair, obesity, menstrual abnormalities, infertility, and enlarged ovaries may have polycystic ovary syndrome (PCOS), an unfortunate condition thought to be caused by excessive secretion by the ovaries of androgen, a hormone associated with male characteristics. Men and women both have hormones expressing male and female characteristics. Yet, the cause of this excessive secretion of a hormone leading to undesired gender traits remains unclear.

Estimates of incidence of this disorder range around the five percent level if both cessation of ovulation and excess hair growth are used in the definition, but they can range over 10 percent in some select populations. Past research emphasized the relative roles of neuroendocrine abnormalities leading to persistent and excessive secretion of luteinizing hormones (LH), one of two glycoprotein hormones that stimulate the final ripening of the follicles and the secretion of progesterone; and the ovarian actions increased insulin in plasma, a consequence of insulin resistance. Additional evidence suggests that unnatural ovarian production of hormonal steroids is a primary abnormality in PCOS.



Human studies of PCOS have found abnormal ovarian steroid responses to administration of gonadial hormones, specifically potent gonadotropin-releasing hormone (GnRH) agonist or a high dose of human chorionic gonadotropin (hCG). The stimuli cause exaggerated secretion of 17-hydroxyprogesterone (17-OHP) and, to a lesser degree, androstenedione, suggesting abnormal ovarian production of steroids. However, these paradigms involve pharmacological ovarian stimulation and do not reproduce physiological LH pulsatility.

Researchers recently hypothesized that near-physiological LH stimuli would effect greater ovarian secretion of androgens and their precursors in women with PCOS compared to controls. To test this supposition, they employed a paradigm of sequential GnRH-receptor antagonist administration to suppress endogenous LH concentrations, and intermittent (pulse-like) infusions of physiological amounts of recombinant human LH (rhLH) to stimulate ovarian steroidogenesis.

A New Study

The authors of “Exaggerated 17-Hydroxyprogesterone Response to Intravenous Infusions of Recombinant Human LH in Women with Polycystic Ovary Syndrome,” are Christopher R. McCartney, Amy B. Bellows, Melissa B. Gingrich, Yun Hu, William S. Evans, John C. Marshall, and Johannes D. Veldhuis, all from the University of Virginia Health System, Charlottesville, VA. Their findings appear in the June, 2004, edition of the American Journal of Physiology – Endocrinology and Metabolism. The journal is one of 14 published each month by the American Physiological Society (APS) (www.the-aps.org).

Methodology

This study sought to assess ovarian steroid secretion in response to near-physiological gonadotropin stimuli in 12 ovulatory controls and 7 women with PCOS. A gonadotropin-releasing hormone-receptor antagonist (ganirelix, 2 mg subcutaneously) was given to block endogenous LH secretion, followed by dexamethasone (0.75 mg orally) to suppress adrenal androgen secretion. Twelve hours after ganirelix injection, intravenous infusions of recombinant human LH were administered at four-hour intervals with the highest dose last. Plasma LH, 17-hydroxyprogesterone (17-OHP), androstenedione, and testosterone were measured concurrently. LH dose-steroid response relationships (mean sex-steroid concentration versus. mean LH concentration over four post-infusion) were examined for each subject.

Results

The increased 17-OHP responses in PCOS observed in the study may reflect exaggerated acute steroidogenic responses that parallel escalating doses of rhLH. However, an alternative explanation is that the 17-OHP increase in PCOS reflects abrupt (in comparison to normal) rhLH-induced resumption of early steroidogenic steps after temporary removal of physiological LH stimulation.

The findings revealed that leuteinizing hormone dose-ovarian steroid responses were not observed in normal women. Furthermore, acute ovarian steroid responses to rhLH infusions were not commonly apparent when reviewing individual steroid time series. It remains possible that ovarian steroid responses could have occurred after our surveillance had ended. Nonetheless, the observations suggest that ovarian steroidogenesis during the normal follicular phase is influenced by integrated LH stimulation and does not vary acutely to changes in LH pulse mass. This contrasts with acute P responses to endogenous LH pulses during the luteal phase.

Conclusions

The authors conclude that that near-physiological ovarian stimulation via intermittent (pulse-like) rhLH administration produces exaggerated 17-hydroxyprogesterone secretion in patients with PCOS, supporting earlier studies of pharmacological ovarian stimulation. The next step in the key to prevention is to determine the physiological mechanisms leading to this disorder.

Donna Krupa | EurekAlert!
Further information:
http://www.the-aps.org

More articles from Studies and Analyses:

nachricht Multi-year study finds 'hotspots' of ammonia over world's major agricultural areas
17.03.2017 | University of Maryland

nachricht Diabetes Drug May Improve Bone Fat-induced Defects of Fracture Healing
17.03.2017 | Deutsches Institut für Ernährungsforschung Potsdam-Rehbrücke

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>