What Are Gonadotropins?

Gonadotropins (Gn) are glycoprotein hormones that regulate the development of gonads in vertebrates and promote the production and secretion of sex hormones. For example, the luteinizing hormone (LH) and follicle maturation hormone (FSH) secreted by the anterior pituitary gland synergistically stimulate the development of germ cells in the ovary or testes and the production and secretion of sex hormones; Gonad hormone (HCG), can promote the secretion of progesterone by the corpus luteum during pregnancy. HCG can appear in the urine during the first trimester of pregnancy, reaching a peak in the second trimester of pregnancy, which is often used as a clinical indicator of pregnancy.

Gonadotropins (Gn) are glycoprotein hormones that regulate the development of gonads in vertebrates and promote the production and secretion of sex hormones. For example, the luteinizing hormone (LH) and follicle maturation hormone (FSH) secreted by the anterior pituitary gland synergistically stimulate the development of germ cells in the ovary or testes and the production and secretion of sex hormones; Gonad hormone (HCG), can promote the secretion of progesterone by the corpus luteum during pregnancy. HCG can appear in the urine during the first trimester of pregnancy, reaching a peak in the second trimester of pregnancy, which is often used as a clinical indicator of pregnancy.

Chinese name

Gonadotropin

Foreign name

gonadotropin, Gn

Applied discipline

biological

Scope of application

medicine

Nature

hormone

Secretion site

pituitary

Chemical nature

protein

The structure of gonadotropin:

GnH includes follicle stimulating hormone (FSH) and luteinizing hormone (LH). It is a glycoprotein hormone that is the same as thyroid stimulating hormone (TSH). Both have two subunits. The three -subunits are the same. Each consists of 89 amino acids, and the specificity of each hormone lies in the -subunit. FSH has a molecular weight of about 37,000 and LH 28,000, and their -subunits each have 115 amino acids. FSH is on the two asparagines at positions 7 and 24, and LH has a carbohydrate moiety on each of the two asparagines at positions 13 and 30.

Gonadotropin secretion mechanism:

FSH and LH are now thought to be derived from different anterior pituitary FSH and LH cells, but some people believe that the lines originate from one type of cell. The diameter of FSH secreted particles is mostly 250-300nm, but the larger one can reach 400-450nm. The secreted particles of LH are 150-350nm, all of which are PAS positive. FSH and LH concentrations in serum and urine have been determined by radioimmunoassay. Due to the impulsive secretion in the daily and monthly periodic changes, the range of variation is quite large. The FSH secretion rate is 20-50 IU per day, and the plasma half-life is 6 hours. The LH secretion rate is 500 to 1,100 IU per day (women most of the menstrual cycle). Plasma half-life was 70 min.

Physiological effects of GnH (1) FSH: Promote follicular development and maturity, together with LH, promote estrogen secretion and further cause ovulation. It can also stimulate the increase of follicular fluid secretion and promote the proliferation of granulosa cells. Cooperate with testosterone to promote testicular seminiferous tubule growth and spermatogenesis.

(2) LH: Follicle maturation and ovulation involved in FSH. Subsequently, the follicles are transformed into the corpus luteum and promote the synthesis and secretion of estrogen and progesterone. Promote the proliferation of testicular mesenchymal cells and secrete androgens, so LH is also known as interstitial stimulating hormone (ICSH).

(3) Changes in GnH during the menstrual cycle: at the beginning of the follicular phase, progesterone and estrogen are at low levels, which weakens the inhibition of the "tensity center" and pituitary of the hypothalamus, and the "tensity center" secretes gonadotropin release The hormone (GnRH, or LRH), promotes the gradual increase of GnH secretion from the pituitary. Under the action of FSH and LH, the follicles gradually develop and mature, and the secretion of estrogen increases day by day. When the follicles mature, there is a peak of estrogen in the body, and a large number of estrogen has a positive feedback effect on the "cycle center" of the hypothalamus, which triggers the large release of GnRH from the "cycle center", the pituitary secretion of GnH reaches a peak, and the average value of the peak plasma LH reaches 83.5 mIU / ml, FSH peak is about 20mIU / ml lower. Large amounts of LH promote follicle maturation and ovulation. Entering the luteal phase, under the action of LH, the secretion of progesterone gradually increases, and the secretion of estrogen increases. Sustained high concentrations of estrogen and progesterone through negative feedback, inhibit the two "central" of the hypothalamus, correspondingly reduce the secretion of LH and FSH from the pituitary gland. If the corpus luteum begins to shrink when not pregnant, the secretion of progesterone and estrogen will decrease. Then the hormone-removing menstrual cramps appeared, and the decline of sex hormones weakened the inhibition of the "tensile center" of the hypothalamus, GnRH began to secrete again, and the pituitary re-secreted FSH and a small amount of LH. The new follicles developed again, and transferred to the next menstrual cycle. .

Regulation of GnH secretion in women: GnRH secreted by hypothalamus regulates the release of pituitary FSH and LH, and FSH and LH may have negative feedback inhibition on GnRH secretion of hypothalamus. Low concentrations of estrogen can enhance the response of the pituitary to GnRH, while high concentrations of estrogen and progesterone can inhibit the response of the pituitary to GnRH. Regulation of the nervous system and neurotransmitters: sensory stimuli (sound, light, odor, etc.) and psychological states, mood swings, and adverse external stimuli all have significant effects on GnH secretion. Dopamine can release hypothalamus GnRH, thereby promoting GnH is secreted, while the effects of serotonin and melatonin are reversed.

Regulation of GnH secretion in men: GnRH in the hypothalamus excites the pituitary to secrete LH and FSH. LH or ICSH can promote testosterone secretion from testicular mesenchymal cells (Leydig cells), and testosterone plays a feedback inhibitory role on the hypothalamus; FSH cooperates with testosterone to promote testicular seminiferous tubule growth and sperm formation, and seminiferous tubules produce a type of inhibin The substance plays a feedback inhibitory role on the hypothalamus. GnH secretion in men is continuous without periodic changes. Nervous system effect: spermatogenesis is controlled and controlled by cerebral cortex-hypothalamus, olfactory brain-hypothalamus, upper thalamus, and pineal gland structure.

The average serum LH follicular period of female adults is 12.8mIU / ml (range 2-30), the average luteal phase is 11.6mIU / ml (range 2-20); the peak menstrual period is 83.5mIU / ml (range 40-200); FSH follicular phase The average value is 8.3mIU / ml (range 5-20), the luteal phase is 6.9mIU / ml (range 5-15), the middle menstrual peak is 19.3mIU / ml (range 12-30), the LH of women after menopause rises about 6 times, and FSH About 12 times, the male adult LH is 10.9 mIU / ml (range 6-30); FSH 7.4 mIU / ml (range 5-25). LH14 25IU / 24h and FSH14 17IU / 24h in men and women were 90IU / 24h and 170IU / 24h in menopause. LH25IU / 24hFSH11IU / 24h in male adults.