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 Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>