Whether your period is normal is not only related to the uterus, but also controlled by the brain

Author: Hao Yanfang, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital

Reviewer: Yu Qi, Chief Physician, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences

"Period" is the "guest" that every woman worries about the most every month. Many women are troubled by its arrival, worried that it will not come, and afraid that it will come at the wrong time.

Once the menstrual cycle and/or menstrual flow become abnormal, women will fall into anxiety and can't help wondering "Is there something wrong with my body?"

First of all, we should know that the causes of menstrual disorders are very complicated and can be roughly divided into two categories: those with changes in the anatomical structure of the reproductive system and those without changes in the anatomical structure of the reproductive system. The main factors causing menstrual disorders with changes in the anatomical structure of the reproductive system include various tumors, inflammation, trauma, and congenital malformations; the main factors causing menstrual disorders without changes in the anatomical structure of the reproductive system include coagulation disorders, ovulation disorders, abnormalities in the local fibrinolytic system of the endometrium, as well as iatrogenic causes caused by certain medical measures and unclassified causes that cannot be determined by examination. Today we will mainly talk about menstrual disorders caused by ovulation disorders.

We know that menstruation refers to the periodic shedding and bleeding of the endometrium accompanying the periodic ovulation of the ovaries, which is a physiological phenomenon. So, does menstrual disorder mean that there is something wrong with the uterus?

In fact, menstrual disorders may be caused by problems with the uterus (especially endometrial damage), congenital dysplasia of the reproductive tract, ovarian dysfunction, central hypothalamus-pituitary lesions, or problems with the coordination of this axis. In other words, menstruation is not only related to the uterus and ovaries, but also controlled by the brain.

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How does menstruation come about?

A normal menstrual cycle in women depends on the dynamic balance between hormones related to the central nervous system-hypothalamus-pituitary-ovarian axis. The central nervous system is the "big leader", the hypothalamus is the "second leader", the pituitary is the "third leader", the ovary is the "group leader", and the endometrium is the obedient "follower".

Every month, the "big leader" center commands the "second leader" hypothalamus to secrete gonadotropin-releasing hormone, which increases the secretion of follicle-stimulating hormone from the "third leader" pituitary gland, promoting follicle development. Under the synergistic effect of a small amount of luteinizing hormone, the follicles in the "team leader" ovaries will continuously secrete estrogen during the joyful growth process. Under the action of estrogen, the endometrial epithelium, glands, stroma and blood vessels continue to proliferate.

As estrogen gradually increases, when the "big leader" center learns that there is already enough estrogen and there is no need to continue increasing the secretion, it inhibits the secretion of gonadotropin-releasing hormone (negative feedback) from the "second leader" hypothalamus, thereby reducing the secretion of follicle-stimulating hormone (follicle-stimulating hormone) from the "third leader" pituitary gland. Most follicles will stop developing or even atrophy and die. Only 1 to 2 high-quality follicles will have the opportunity to continue developing until maturity. This is also the main mechanism for selecting dominant follicles.

As the follicles in the ovaries of the "team leader" gradually develop and mature, the estrogen level reaches a peak, which in turn promotes the "big leader" center and the "second leader" hypothalamus (positive feedback), prompting the "third leader" pituitary gland to release a large amount of luteinizing hormone, resulting in a luteinizing hormone peak. At the same time, the follicle-stimulating hormone also forms a lower peak. A large amount of luteinizing hormone works synergistically with follicle-stimulating hormone to cause the mature follicles in the ovaries of the "team leader" to ovulate.

However, the ovulation process is just a "lone journey" of the oocyte carrying a small amount of granulosa cells. The substances such as the follicle membrane and follicle wall left behind will be transformed into a corpus luteum under the action of luteinizing hormone, which is responsible for secreting estrogen and progesterone.

Progesterone changes the endometrium from the proliferative phase to the secretory phase, creating a hotbed for the implantation of the fertilized egg in the second half of the menstrual cycle. Once the sperm and egg combine, the fertilized egg will take root and sprout in the endometrium. Progesterone is responsible for making the endometrium thicker, softer, and more nutritious, allowing the embryo to grow smoothly.

However, if the oocyte does not wait for the sperm, the corpus luteum will begin to strike about 10 days after ovulation, and the levels of estrogen and progesterone will drop rapidly, causing the endometrium to shedding, accompanied by rupture and bleeding of blood vessels in the uterine cavity, and menstruation will occur.

It can be seen from this that whether menstruation is normal or not depends on the joint action of the "big leader" center, the "second leader" hypothalamus, the "third leader" pituitary gland, the "team leader" ovary, and the "follower" uterus.

Under what circumstances will our “big leader”, “second leader” and “third leader” behave abnormally?

Excessive dieting can affect the central nervous system

Influenced by the current trend of being "white, thin and young", many women with normal body shapes have developed body anxiety. Even those who were originally healthy have gradually joined the ranks of weight loss. In order to achieve the effect of rapid weight loss, many women often resort to excessive dieting, but this approach is very harmful to the body.

Excessive dieting will suppress the feeding center and satiety center in the hypothalamus. Although weight loss can be achieved in the long run, long-term dieting, malnutrition, underweight, stress and mood changes will suppress the nerve centers above the hypothalamus. The center is the highest level organ that controls ovarian function. When the center is suppressed, ovarian function may decline to varying degrees.

In the case of less severe central inhibition, follicles grow but no ovulation occurs. At this time, estrogen can be secreted, but progesterone is not secreted, which causes menstrual disorders. In the case of severe central inhibition, follicles stop growing and remain in the small follicle stage, forming hypothalamic amenorrhea. Due to the inhibition of ovulation, the ovaries may show polycystic changes. Due to the decrease in estrogen secretion, the effect of androgen becomes apparent, and symptoms of high androgen such as acne and hirsutism often appear.

Therefore, being thin is not necessarily the real beauty. There are many hidden dangers behind it. Ladies, weight loss should be done in moderation. Health is the most beautiful thing. Refuse the harm caused by excessive dieting to our body.

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Beware of pituitary tumors

The pituitary gland is a special and vital organ, located in the "CBD center" of the brain - the pituitary fossa, a unique place. Although the pituitary gland is only the size of a pea, it is the most complex endocrine gland in the human body and plays a vital role.

The pituitary gland is divided into two parts: the neurohypophysis and the adenohypophysis. Among them, the neurohypophysis mainly secretes antidiuretic hormone and oxytocin. The adenohypophysis mainly secretes growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, prolactin, etc., which play an important role in regulating growth, development and metabolism, and also affect the functions of other endocrine glands, such as the thyroid, adrenal glands, gonads, etc. If the human neuroendocrine system is likened to a troop, then the pituitary gland is like a "headquarters" and is the "master switch" that regulates the balance of human health.

Although the pituitary gland is small, there are many types of related diseases, the most common of which is pituitary tumor. The pathogenesis of pituitary tumors is still unclear, but fortunately, most pituitary tumors are benign. Depending on the symptoms, that is, whether the pituitary tumor cells produce hormones, they can be divided into two categories: functional pituitary tumors and non-functional pituitary tumors.

The most common type of pituitary tumor is a prolactinoma, which is a functional pituitary tumor. Female patients with prolactinomas often present with problems such as lactation, infrequent or even absent menstruation, repeated miscarriages, infertility, and so on. Therefore, if a woman has symptoms of menstrual disorders and also has lactation, she must pay attention to whether she has a pituitary tumor[1].

If the pituitary tumor is not discovered for a long time, the patient will experience headaches, decreased vision, and visual field defects in the later stage due to the enlargement and compression of the tumor. If the above symptoms occur, please go to the hospital for relevant examinations in time.

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Now we know that there are many reasons for menstrual disorders. We cannot just blame the uterus and ovaries. We also need to check whether the central nervous system, hypothalamus and pituitary function are normal. When menstruation is abnormal, you must seek medical attention in time. The doctor will determine the cause based on the specific symptoms and examination results. Identifying the cause and symptomatic treatment are the key to treating menstrual disorders.

References

[1] Chen Gang. Menstrual disorders and decreased vision, the “culprit” is actually hidden in the brain. Wish you good health, 2020(5): 24-25.