Epistemology and endocrinology : the hypothalamic-hypophysis-ovary axis revisited. Rev Colomb Obstet Ginecol [online]. ISSN History of the discovery of the hypothalamic-pituitary-ovarian axis and its role in nervous, endocrine and reproductive systems is related to conceptions about the existence of subtle substances formerly named animal spirits and recently as hormones, neurotransmitters, and others. This scheme was broken for another discoveries: hormone feed-back -one effect may acts on its own cause-, and multiple factors, including outside the system, have a random influence. So, diagnostic and therapeutic methods may be insufficient for its purposes.
|Published (Last):||17 October 2004|
|PDF File Size:||5.99 Mb|
|ePub File Size:||4.37 Mb|
|Price:||Free* [*Free Regsitration Required]|
Autores: Yanara A. Sin embargo, a pesar de la gran importancia de este signo de salud, muchas mujeres desconocen su relevancia e impacto en su vida diaria. El ovocito puede sobrevivir de 12 a 24 horas. La baja de las hormonas estradiol y progesterona, permite el comienzo de un nuevo ciclo de reclutamiento folicular. Esto es de mucha utilidad tanto para la mujer como para los profesionales de la salud.
Es una herramienta valiosa que fomenta el autoconocimiento de lo que ocurre en el ciclo mes a mes. Ovulation is among the most trustworthy signs of health in women of reproductive age. It is an indicator that allows to assess the hormonal and reproductive status of women. There are physiological conditions such as pregnancy or lactation, which produce an anovulatory state.
During puberty and perimenopause, it is expected to find irregular ovulatory cycles, since these are considered as transition periods. However, outside these normal situations, irregular ovulatory or anovulatory cycles can be signs of an unhealthy lifestyle or illness.
Stress, endocrine, gynecological and genetic disorders, iatrogenic causes or the use of medications as hormonal contraceptives, can disrupt ovulation, often being the first sign of a hormonal disorder. However, despite the importance of this sign of health, women are unaware of the relevance of their ovulation and the impact it has on their daily lives. If women knew the real meaning of this sign, they could detect a lot of health problems earlier.
A series of complex structures interact with each other in order to achieve ovulation. The ovaries, together with the uterus and oviducts uterine tubes or Fallopian tubes , are part of the internal female genitals. The ovaries are responsible for the production of sex hormones, estradiol and progesterone, and the development of follicles. A follicle is a structure formed by the oocyte the germinal cell surrounded by somatic cells granulosa cells.
According to their developmental stage, follicles can be classified as primordial, primary, secondary, tertiary, mature Graafian , corpus luteum and Albicans.
The central nervous system CNS is a specialized structure that controls the functions related to motor, behavioral, cognitive and neuroendocrine coordination of the body. Hormones have an important effect upon the wiring of different brain areas, including the hypothalamus and pituitary gland.
The CNS is regulated by hormonal feedbacks. The main structures of the CNS involved in the regulation of ovulation are the hypothalamus and pituitary gland. Kisspeptin, a neuropeptide recently identified is synthesized by neurons located in the hypothalamus. The gonadotropic hormones act upon the ovaries, where sex hormones are produced. Women between 12 and 50 years of age normally exhibit regular ovulations characterized by 24 to 36 days cycles with fluctuating plasma estradiol and progesterone levels according to the different phases of the cycle.
The first phase of the menstrual cycle is characterized by an increase in estradiol secretion by growing follicles. This phase starts with the first day of menstruation and lasts until ovulation. The luteal phase begins after ovulation and goes until the day before next menses.
It is characterized by an increase in progesterone production by the corpus luteum. The coordinated hormonal events required for ovulation are a growth and development of an ovarian follicle and its oocyte, b ovulation, c preparation of the uterine lining endometrium to receive the zygote and d endometrial lining detachment menstruation , when fertilization does not occur.
At the beginning of each cycle, there is an increase in FSH levels that cause recruitment and development of antral follicles. FSH also triggers a progressive rise in estrogen production and secretion. After follicular recruitment, estradiol causes a decrease in FSH levels. A dominant follicle is selected, while the rest of the follicles degenerate. The dominant follicle produces increasingly higher levels of estradiol, which in turn stimulate kisspeptinergic neurons. Kisspeptin induces GnRH secretion and the pre-ovulatory LH peak, which initiates follicular luteinization leading to the formation of the corpus luteum.
Before the initiation of the midcycle gonadotropin surge, a pre-ovulatory rise in progesterone occurs. This early progesterone rise produced by the pre-ovulatory follicle is critical for follicular rupture, a necessary process for ovulation.
Progesterone maintains the LH peak causing follicular rupture, with the consequent release of the oocyte.
The released oocyte will typically survive 12 to 24 hours. LH and progesterone contribute to the development and maintenance of the corpus luteum, which continues to produce progesterone and estrogen during the luteal phase. Normally this phase lasts for 11 to 16 days. If fertilization does not occur, the corpus luteum starts to regress. This regression causes a drop in estrogen and progesterone levels. The decrease in both hormones eliminates the suppression and a new cycle begins.
Recognizing ovulation enables women and couples to identify the day when the probability of conception reaches its peak. With the signs given by the presence or absence of cervical mucus on the vulva, it is possible to identify the fertile window. Cervical mucus undergoes several modifications during the phases of the reproductive cycle. Two main types of cervical mucus have been described: estrogenic and progestagenic.
Increased estrogen levels halfway through the follicular phase result in a noticeable rise in the secretion of estrogenic mucus. The estrogenic cervical mucus is, transparent, fluid and crystalline, giving a slippery sensation in the vulva. During this period, cervical mucus allows sperm selection and ascent. Progesterone has the opposite effect of estradiol upon cervical mucus antiestrogenic action. It inhibits production and changes the characteristics of the mucus to an opaque and less fluid mucus, with- out the ability to crystallize into palm leaf patterns.
The observation of changes in cervical mucus is considered a reliable biomarker as it has been demonstrated that recognizing mucus patterns can help women to identify the different stages of the ovarian continuum. Endocrine abnormalities that can lead to ovulatory dysfunction are i androgen disorders such as polycystic ovary syndrome, manifesting in women with acne, hirsutism, alopecia, increased body weight and mood changes; ii increase in prolactin levels caused by stress, pituitary tumors, and some drugs.
In these cases we can observe short luteal phases, anovulation, menstrual irregularities, amenorrhea, galactorrhea, skin dryness, immunological disorders, low libido, hot flashes, and sweaty hands; iii thyroid disorders such as hypothyroidism which can lead to irregular menses, hypermenorrhea, metrorrhagia, and spotting, in addition to this, it is also associated with depressive symptoms, fatigue, lethargy, weight gain, cold intolerance and hair loss; iv increase in insulin levels, caused by insulin resistance related in some occasion to obesity, weight gain, anovulation, menstrual irregularities, and amenorrhea.
Often, healthcare providers have focused on regularizing bleeding patterns, without paying attention to ovulation in reproductive age women. For this reason, cycle charting is a valuable tool that empowers women, promoting self-knowledge and health care.
Influence of sex steroid hormones on the adolescent brain and behavior: An update. This review explains the main effects exerted by sex steroids and other hormones on the adolescent brain.
During the transition from puberty to adolescence, these hormones participate in the organizational phenomena that structurally shape some brain circuits. In adulthood, this will propitiate some specific behavior as responses to the hormones now activating those neural circuits. For this reason, the adolescent years are very important for future behaviors in human beings. Consequently, understanding the link between adolescent behavior and brain development as influenced by sex steroids and other hormones and compounds is very important in order to interpret various psycho-affective pathologies.
Lay Summary : The effect of steroid hormones on the development of the adolescent brain, and therefore, on adolescent behavior, is noticeable. This review presents their main activational and organizational effects. During the transition from puberty to adolescence, organizational phenomena triggered by steroids structurally affect the remodeling of brain circuits. Later in adulthood, these changes will be reflected in behavioral responses to such hormones. The understanding of the relationship between adolescent behavior and the way hormones influence brain development help understand some psychological disorders.
Women start their reproductive years with approximately five hundred thousand follicles containing oocytes, of which only around five hundred will be released during ovulation. Ovulation has been recognized as an event linked with reproduction; however, recent evidence supports the role of ovulation as a sign of health. The use of biomarkers that help women recognize ovulation enables them to identify their health status.
This knowledge helps medical healthcare providers in the prevention, diagnosis, and treatment of different pathologies related with endocrine disorders, gynecological abnormalities, autoimmune, genetic, and neoplastic diseases, as well as pregnancy-related issues.
The knowledge of the ovarian continuum and the use of biomarkers to recognize ovulation should be considered a powerful tool for women and medical professionals.
It begins during intrauterine life with fertilization and ends with menopause. This process can be greatly affected by different conditions such as changes in hormonal levels and illnesses. Therefore, understanding and promoting the knowledge and use of biomarkers of ovulation in women is a key aspect to consider when evaluating their health status.
The knowledge and education about the ovarian continuum should be taken into account as a powerful tool for women and medical professionals. Alliende, Natalia Molina, Felipe G. Serrano, Santiago Molina and Pilar Vigil. Throughout the different stages of life, from menarche to menopause and all stages in between, women experience dramatic fluctuations in the levels of progesterone and estradiol, among other hormones.
These fluctuations affect the body as a whole, including the central nervous system CNS. In the CNS, sex hormones act via steroid receptors. They also have an effect on different neurotransmitters such as GABA, serotonin, dopamine, and glutamate. Additionally, studies show that sex hormones and their metabolites influence brain areas that regulate mood, behavior, and cognitive abilities.
This review emphasizes the benefits a proper hormonal balance during the different stages of life has in the CNS. Knowledge of steroid hormone activity in the brain will give women and health providers an important tool for improving their health and well-being. Fertility awareness constitutes fundamental knowledge for every woman and is an important tool for health professionals. The main techniques for detecting ovulation are explained, and then the events that characterize a normal menstrual cycle are discussed.
The relevance of cervical mucus from the perspective of female fertility is highlighted. Finally, the usefulness of fertility awareness 1 to identify fertile and infertile periods, 2 to help to detect several pathologies, and 3 in regards to how it exerts an important role in the success of programs in education for affectivity and sexuality are discussed.
HOME Publicaciones. Ovulation, a sign of health. The Linacre Quarterly. Vigil P. Third Edition. White paper.
EJE HIPOTALAMO HIPOFISIS OVARIO