The hypothalamus is a small formation almost in the very centre of the brain, which is the real conductor of the endocrine processes of our body. It, with the help of its “right hand” pituitary gland, regulates the secretion of hormones that will further influence not only directly on the organs (vasopressin – on the kidneys, oxytocin – on the uterus), but also on the synthesis of active substances in other endocrine glands (thyroid – on the “thyroid”, adrenocorticotropic – on the adrenal glands, etc.). One of the most important components of normal pituitary function is the feedback mechanism. Here is an example of negative feedback. If the thyroid gland produces too many hormones, their excessive amount gives the pituitary gland a “stop” signal, and it stops stimulating this gland to release its hormones by stopping the synthesis of thyroid hormone (thyroid-activating hormone). Positive feedback is observed in the opposite situation: if the level of thyroid hormones is too low, the hypothalamic-pituitary system works to increase the secretion of thyroid hormone and thus increases the production of thyroid hormones – triiodothyronine, thyroxine and calcitonin, involved in stimulating the processes of differentiation, growth and development of tissues, as well as in improving metabolism.

The hypothalamus in response to a stressful situation easily and simply increases the production of a special hormone – corticoliberin. Once in the pituitary gland, it stimulates the release of the next hormone – adrenocorticotropin, which leaves the bloodstream from the brain and is delivered to the adrenal glands – small endocrine glands located on the “top” of the kidneys. These glands, in turn, begin to secrete the “stress hormone” – cortisol, as well as the well-known adrenaline and noradrenaline. Then a very important thing happens: cortisol inhibits the continuation of the release of hormones, which due to the primary action of stress began to be synthesised at the very beginning of this “hormonal cascade” – the hypothalamus. You bet! After all, prolonged exposure to corticoliberin can lead not only to increased anxiety, but also to depression (and even panic states)! As a result of activation of this long chain – or, as it is correctly called, the hypothalamic-pituitary axis – appetite decreases, heart rate increases, blood pressure rises and sweating increases.

Another hormonal axis of the body, the hypothalamic-pituitary-gonadal axis, links the hypothalamus-pituitary pair with the organs of the sexual system. It begins with the synthesis of the hormone gonadoliberin in the hypothalamus (which, based on the name of the axis, is not surprising). This hormone keeps its way to the pituitary gland and stimulates here the production of two other hormones – luteinising and follicle-stimulating. They are released into the blood and precisely directed to their target tissues – reproductive organs. Here the synthesis of sex hormones – estrogen in the ovaries and testosterone in the testes – takes place. In general, both of these hormones are formed in the male reproductive organs, as well as in the female, just in different ratios: estrogen predominates in women, and testosterone more in men. What is interesting is that in critical situations the synthesis of gonadoliberin is reduced by the release of corticoliberin (remember such a “stressful” mate from the adrenal axis?). It turns out that if you worry a lot, it is quite likely to meet with a decrease in sexual desire and reproductive function in general. Thus, in the endocrine system, inter-regulation is possible not only between organs, but also between entire “hormonal” axes. This gives our organism a tremendous opportunity for close “communication” between different organ systems and tissues, and also determines its adequate response to external factors by activating or suppressing the functions of these very organs.