What relationship do the hormonal changes that occur during menopause with aging in women?
The World Health Organization has defined the perimenopause as the period preceding the cessation of menopause, and lasts for a year following the last cycle of spontaneous bleeding. On average, this period has a duration of 3 years.
Still no known biochemical findings that reliably indicate the onset of menopause. However, blood levels of the hormone tend to increase in women who are still menstruating normally about the end of the premenopausal (42-50 years), and there are changes in the rate of secretion and the availability of other hormone, LH. The secretion of estrogen in perimenopause is, meanwhile, variable, and includes intervals of increased secretion, probably caused by increased stimulation by FSH.
The “heat” may precede the onset of anovulatory cycle in perimenopause. Physical symptoms, such as tension in the breasts, irregular menstrual bleeding, “hot flashes”, and dyspareunia (painful intercourse) and emotional symptoms such as disrupted sleep, fatigue, tension, and irritability are regularly present in all menopausal women.
Individual variations in aging female
Even identical twins can have 12 to 14 years of discordance in the age at menopause, although fifty percent of twins are concordant within two years.
Therefore, the aging female reproductive tract depends not only on genetic factors but also. This could arise from non-uniformity between different people in prenatal survival rates of oocytes (cells that give rise to eggs) and follicles, and highlights the importance of the ovarian reserve of oocytes.
In other words, all women do not come into the world with the same amount of potential ova, and this is a factor in the age at onset of menopause: the greater the amount of oocytes, later age of onset of menopause.
The aging of the ovary
Women have a limited, non renewable, oocytes. Therefore, the lower control oocytes is critical in determining the length of the female reproductive life. It is estimated a maximum population of 7 million oocytes, at 20 weeks gestation. Two million persist until birth, and about 400,000 until the onset of puberty. Only 400 oocytes, some are actually ovulated during a woman’s reproductive years. Understanding the mechanisms regulating oocyte depletion is critical to develop strategies to extend the reproductive life, speaking in premature ovarian failure, and preserving gonadal function in women treated with chemotherapy for cancer.
In the preservation or destruction of the oocytes play a pivotal role a group of substances called modulator of apoptosis (esfingomilinasa, ceramide, Bcl-2, Bax protein, etc.).. For example, Bax promotes the “loss” of oocytes by acting on the primordial follicles. The decline of this Bax in experimental conditions, results in a marked expansion in the reproductive life in mice. Furthermore, the gonadotropins (other hormones) rescued more mature follicles, opposing the destruction of other different follicle cells of oocytes, granulosa cells.
Finding drugs that promote the protection follicular could, for example, limiting premature menopause in women receiving chemotherapy.
Hormonal factors in developing breast cancer after menopause
The incidence of breast cancer increases with age. A large study (the National Surgical Adjuvant Breast and Bowel Project) evaluated 13,000 women treated for 5 years with placebo or tamoxifen. Tamoxifen is a drug that acts as an antagonist of estrogen action in breast tissue. Patients receiving tamoxifen achieved an 50% reduction in invasive breast cancer development.
This is because estrogens bind to a receptor on the surface of breast cells, which induces the action of substances called growth factors (GF) and possibly also of genes that stimulate the growth of cancer cells.
However, the clinical data available so far, found no relationship between treatment with growth hormone (HGH) and the development of breast cancer.