Premenstrual syndrome gene
Scientists at Rockefeller University (New York), working under the leadership of Bruce McEwen (Bruce S. McEwen), identified a gene apparently involved in the development of premenstrual dysphoric disorder, known as premenstrual syndrome (PMS), and other unpleasant symptoms associated with natural hormonal changes during the monthly cycle.
In the article "BDNF variant Val66Met interactions with estrous cycle in the control of hippocampal function", published in the preliminary on-line version of the journal Proceedings of the National Academy of Sciences, the authors describe in detail their experiments on mice demonstrating that a common variant of one of the genes changes the nature of the effect of the female sex hormone estrogen on the brain, resulting in increased anxiety, suppression of curiosity and memory impairment. The authors believe that the identification of this genetic variant can help in the diagnosis and treatment of various disorders associated with certain phases of the menstrual cycle and the development of menopause.
The protein product of the BDNF gene, the brain–derived neurotrophic factor, in addition to other functions performed by it, together with estrogen increases the adaptability of hippocampal neurons, a region of the brain that plays a key role in mood formation, as well as providing cognitive ability and memory. A change in one of the nucleotides in the gene leads to the fact that the amino acid valine in the 66th position from the beginning of the protein chain changes to methionine. Approximately 20-30% of women with white skin color are carriers of the genetic variant of BDNF Met. The results of earlier work showed that this genetic variant is a risk factor for psychiatric problems, such as depression and bipolar disorder, and is generally associated with increased anxiety and a tendency to memory disorders.
In collaboration with colleagues from Cornell University Medical College (Ithaca, New York), the authors demonstrated that mice carrying the BDNF Met variant are generally more timid. When placed in a well-lit aviary, before hiding in a darkened corner, they spent much less time in its center. As a result, they devoted less time to studying the objects placed in the cage.
Differences in the cognitive function of two populations of mice were assessed using two tasks. When performing one task, the animals had to remember the location of the object in the cage, and when performing the second, they had to recognize the difference between two similar objects (for example, a small bottle of pills and a bottle of nail polish of the same size) placed in the cage at intervals of 5 and 30 minutes. Mice carrying the genetic variant of BDNF Met showed the worst results when performing both tasks, while their intelligence depended on the phase of the hormonal cycle.
The study of animal hippocampuses in search of biochemical causes underlying this phenomenon has shown that carriers of the genetic variant of BDNF Met are characterized by increased production of both the BDNF protein itself and its TrkB receptor. At the same time, in a certain phase of the hormonal cycle, similar to the imminent beginning of the "critical days" in Homo sapiens females, and characterized by a high level of estrogen, the level of BDNF in the hippocampus of such animals becomes even higher. The researchers believe that in this way the hippocampus, responsible for remembering the events currently taking place, tries to compensate for the generally reduced production of BDNF, characteristic of neurons carrying the BDNF Met gene.
It is not yet clear how these changes affect behavior, but the relationship with the hormonal cycle indicates that the genetic variant of BDNF Met plays an important role in the development of disorders associated with the menstrual cycle, or the so-called premenstrual syndrome, among other symptoms characterized by increased irritability and mood swings. According to statistics, 5-10% of women suffer from PMS. (Maybe this is a typo and should read "5-10% do not suffer"? – approx. transl. :)
In addition to clarifying the mechanisms of development of premenstrual syndrome, the data obtained by scientists deepen the understanding of the basic cellular and molecular mechanisms underlying the effects of sex hormones on behavioral features not related to reproductive function.
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Rockefeller University: Research identifies gene with likely role in premenstrual disorder.
12.02.2010