The sex hormones are of two types: Protein S or Stéroïde S. the steroids have a molecular weight around 300 dalton S; they thus have a small size. Considering their size and their liposolubility, they can diffuse freely in the cell S targets. Consequently them receiving S is intracellular. By opposition, the proteins, with a molecular weight higher than 5000, cannot penetrate in the cells and their receivers are thus receiving membrane. Since the steroids are liposoluble, it can only circulate in blood related to nonspecific proteins like the Albumine or on specific proteins like SHBG (sex hormone binding globulin). The proteinic hormones, on the other hand, are water-soluble and circulate freely in blood.

Proteinic hormones

=== gonadotrophines=== The Gonadotrophine S are hormones produced by various fabrics (Hypophyse and Placenta) whose principal function is the regulation of the gonades (ovary S and Testicules). The gonadotrophines include/understand the FSH (folliculostimulating hormone), LH (luteinizing hormone) and the hCG (human chorionic gonadotropin).

The hormone folliculostimulante

The folliculo-stimulative Hormone (FSH) is a Glycoprotéine of a molecular weight from approximately 30.000 daltons produced by the pituitary gland. It is a hétérodimère because it is made up of two different sub-units: α and ß. The sub-unit α (89 amino-acid ) is common to all the gonadotrophines, including the Hormone thyréotrope. The sub-unit ß (118 amino-acids), on the other hand, is specific hormone. The principal function of the FSH is to promote and support the growth of the follicules ovariens at the woman and the Spermatogenèse at the man. The FSH stimulates the synthesis of its own receiver in the cells of the granulosa and the Cellules of Sertoli. It also stimulates the activity of the Aromatase in the cells of the granulosa (Enzyme which allows the conversion of the Androgène S into estrogen S). The FSH is thus also responsible for the “choice of the follicule dominating”. The synthesis and the secretion of the FSH by the pituitary gland are under the control of various regulators such as GnRH (gonadotropin releasing hormone of hypothalamic origin), the estrogenes ovariens, the activine and the Inhibine (both of gonadic origin).

The hormone lutéinisante

The hormone lutéinisante (LH) is a glycoprotéine of a molecular weight from approximately 30.000 daltons produced by the pituitary gland. It is a hétérodimère because it is made up of two different sub-units: α and ß. The sub-unit α (89 amino-acids) is common to all the gonadotrophines and the hormone thyréotrope. The sub-unit ß (115 amino-acids), on the other hand, is specific hormone. The principal functions of the LH are to promote the synthesis of the androgens by the cells Thécal are ovary and the interstitial cells of the testicle, to start ovulation (by stimulation of a cascade of proteolytic enzymes leading to the rupture of the basal membrane of the follicule) and with maintains yellow Corps during the menstrual Cycle. The synthesis and the secretion of LH by the pituitary gland are under the control of various regulators such as the GnRH (gonadotropin releasing hormone of hypothalamic origin ) and the estrogens ovariens.

The hormone Chorionique gonadotrophine

The chorionic hormone gonadotrophine (hCG) is a glycoprotéine of a molecular weight from approximately 43.000 daltons produced by the Syncytiotrophoblaste. It is a hétérodimère because it is made up of two different sub-units: α and ß. The sub-unit α (89 amino-acids) is common to all the gonadotrophines and the Hormone thyréotrope. The sub-unit ß (145 amino-acids), is specific hormone and is distinguished from the sub-unit ß of the LH only by 30 amino-acids in the final part C of the molecule. The hCG whole molecule is also called holo hCG to distinguish it from the hCG usually measured in the laboratories which is the total hCG (holo hCG + free sub-unit ß), the free sub-unit ß also circulating in blood. A particular form of hCG, called nick hCG, is a holo hCG or a free sub-unit ß whose connection between the amino-acid 46 and 47 of the sub-unit ß was broken. This confers on the molecules a particular three-dimensional form which is not inevitably recognized by all the antibodies used for proportioning. The pattern recognition “nick” is particularly important during proportionings of hCG carried out in order to determine the risk of trisomy 21 (known also under the names of What yew, double test or triple test) because in this case the form “nick” is strongly increased. The function of the hCG is primarily the maintenance of the yellow body of the pregnancy and its secretion of Progestérone. But it has also an anti-gonadotrope effect since it inhibits the secretion of the LH and the FSH. The hCG is known as steroidogene since it supports the progesterone secretion of the yellow body but also because it stimulates the secretion of the steroids of the fetal gonades. The regulation of the synthesis and the secretion of hCG is ensured by GnRH trophoblastic.

Prolactin

The human Prolactine (Prl) is a not glycosylée protein which consists of a simple polypeptide chain of 198 amino-acids. Prl is structurally similar to the hPL (human placental lactogen) and with growth hormone GH (growth hormone). In circulation, Prl appears in monomeric form (little prolactin) or in polymeric form (big or big-big prolactin). The quantitative relation between these various forms varies according to the physiological and pathological conditions and the nature of the antibodies used for their proportioning. Prl is primarily of origin hypophyseal but the cells stromales of the Endomètre in secretary phase also produce Prl; it is even a marker of the decidualisation. The principal biological function of Prl at the woman is to control the development mammaire and the Lactation. The role of Prl at the man and that of Prl endométriale at the woman remains still unknown. If the Progestérone is the principal regulator of Prl endométriale it is primarily the Dopamine (formerly called CONK or prolactin inhibiting Factor) which controls hypophyseal Prl. However the TRH (thyroid stimulating hormone releasing hormone) and the VIP (vasoactive intestinal peptide) have the property to stimulate the hypophyseal discharge of Prl.

The hormones stéroïdiennes

See also: sexual Steroid

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