New sex hormone – for contraception and treatment
Almost 10 years after the discovery in birds of a previously unknown peptide regulator – gonadotropin inhibitor hormone (GnIH), suppressing the synthesis of gonadotropin hormone and stopping reproduction, neuroscientists at the University of California at Berkeley, working under the leadership of George Bentley, found that the human body also synthesizes this peptide. This finding will allow specialists to develop a fundamentally new class of contraceptives and, possibly, new methods of treating cancer and other diseases.
The effects of the gonadotropin inhibitor are opposite to the effects of the most important sex releasing factor, gonadoliberin (gonadotropin releasing hormone, GnRH). While gonadoliberin triggers a cascade synthesis of hormones that stimulate sexual behavior and reproduction, a gonadotropin inhibitor blocks this cascade.
The gonadotropin inhibitor was first identified in 2000 in quails, after which it was found in other bird species, as well as in mice and sheep. The presence of a gene encoding this peptide in the human genome has been proven, but scientists have not been able to determine which cells and under what conditions it is synthesized and whether it affects reproductive mechanisms.
The authors were able to identify two variants of a gonadotropin inhibitor from the human brain. They found that the gene encoding it produces a precursor protein, which is subsequently shortened to form two variants of peptides with lengths of 12 and 8 amino acids. The structure of one of these peptides is similar to that of sheep hormone, which will greatly facilitate the study of its activity.
In addition, it turned out that the gonadotropin inhibitor has an effect on the activity of neuroendocrine cells secreting gonadoliberin, which corresponds to the results of earlier studies, according to which it suppresses the activity of gonadoliberin. Finally, the authors found that gonadotropin inhibitor receptors exist in the cells of the hypothalamus and pituitary gland – the two main structures of the brain that control the activity of the entire endocrine system, including the work of the endocrine glands related to the reproductive system and sexual behavior.
According to Bentley, the gonadotropin inhibitor has an effect on reproductive function through several mechanisms. It can affect the hypothalamic neurons synthesizing gonadoliberin, inhibiting the release of this hormone, acting on the pituitary gland, or directly on the sex glands. Ultimately, all these influences suppress the ability to reproduce, but this suppression occurs at different levels.
Currently, Bentley's group continues to study the functions of the gonadotropin hormone inhibitor in humans, as well as birds and fish. The authors believe that the discovery of a gonadotropin inhibitor in the human brain will force experts to reconsider the established views on the mechanisms of regulation of human reproduction. They hope that the results of their work, published on December 22 in the preliminary on-line version of the journal PLoS ONE in the article "Identification of Human GnIH Homologs, RFRP-1 and RFRP-3, and the Cognate Receptor, GPR147 in the Human Hypothalamic Pituitary Axis", will allow the development of effective methods of contraception, as well as treatment infertility and premature puberty. In addition, it is known that sex hormones often stimulate the growth of cancer cells, so a gonadotropin inhibitor can theoretically be used as an antitumor agent.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru According to ScienceDaily: New human reproductive hormone could lead to novel contraceptives.
24.12.2009