The hormones, that control, regulate and maintain the development of secondary sex characteristics and affecting the growth or function of the reproductive organs are termed as sex hormones. Sex hormones may produce by the sex glands or by other glands.The most important female sex hormones are Estrogen, Progesterone, Testosterone, Follicle Stimulating Hormone and Lutenising Hormone. Estrogen, testosterone and progesterone are steroidal in nature, whereas follicle stimulating hormone and lutenising hormone are non steroid hormones (for this reason sometime they are not considered as sex hormones, actually they are gonadotrophic hormones).
Estrogen : Estrogen is a steroid hormone. The three main natural forms of estrogens are estrone (E1), estradiol (E2) and estriol (E3). Estrone and estriol are predominant during pregnancy, estradiol is predominant during premenopause, or when women have cycles.
Xenoestrogens and phytoestrogens are non steroidal in nature but they are not synthesised in human body. These typically are produced by plants and have little to no affect in humans.
Estrogen is primarily produced by ovaries but also produced in liver, adrenaline glands and breasts in lesser amount.
The main functions of Estrogen are : Estrogen enters all cells but the response of estrogen depends on the presence of estrogen receptors (ER) in the particular cell. Generally ER is expressed in female sex organs like ovary, uterus and breasts. Estrogen enters passively in the target cells and bind with the estrogen receptor and then activates the receptor, resulting in a particular function for the cell.
The primary functions of estrogen are development of female secondary sex characteristics (development of breasts, growth of underarm and pubic hair, widening of hips and distribution of fats around buttocks and thigh) maintaining menstruation cycle and estrous cycle (thickening of the endometrium, thickening of the vaginal wall, increased uterine growth and increased vaginal lubrication). Estrogen with Progesteron prepare the uterus for pregnancy and the development of the foetus. Hike in estrogen level induce the release of Lutenising hormone, that triggers the release of ovum from Graafian follicle in the ovary.
Other functions of estrogen are as follows:
- Increase bone formation
- Increase adhesiveness of the platelates
- Increase in the level of High Density lipoproteins and triglyceride
- Decrease Low Density Lipoproteins
- Retention of sodium salts and water
- Reduce bowel movement
- Increase of cholesterol in bile
- Increased libido
- It is considered that estrogen play important role in mental health of women. Withdrawal of estrogen, fluctuation in estrogen level and menopause (decrease in estrogen level) may cause depression, mood swings and anxiety.
Medical Application of oestrogen :
Contraceptives : Synthetic estrogen with synthetic progestin used as oral contraceptives.
Hormone Replacement Therapy : Estrogen is used in hormone replacement therapy to reduce menopausal syndromes.
Progesteron : Progesteron is the major naturally occurring human progestogen (five major classes of steroid hormones, that are characterized by 21-carbon skeleton called pregnane skeleton) It is another important female sex hormone. Progesteron sometime also referred as ‘hormone of pregnancy’ due to it’s various role in the development of the foetus.
Functions of progesteron : The main functions of progesteron is to prepare womb or uterus for pregnancy and the proper development of foetus.
- Progesterone changes the normal endometrium to its secretory stage for the implantation and also helps in the thickening of the vaginal epithelium and cervical mucus, making it impenetrable to sperm.
- During pregnancy, progesterone helps to decrease the maternal immune response to allow for the acceptance of the pregnancy.
- Progesterone inhibits lactation in the time of pregnancy. The drop in progesterone levels following delivery is one of the causes, that triggers lactation.
- Progesteron also helps to reduce spasm, acts as an anti inflammatory agent, regulates the immune response and it also plays an important role in the signaling of insulin release causing gestational diabetes.
Medical Application of Progesteron :
- Progesteron is helpful preventing pre term birth.
- Progesteron is used in Hormone Replacement therapy.
Follicle Stimulating hormone (FSH) : FSH is a gonadotrophic hormone secreted from anterior pituitary. It is non steroid hormone.
As the name implies FSH stimulate and control overall growth of the ovarian follicle including developing of the egg. FSH also stimulate the secretion of estrogen needed for ovulation, as the level of estrogen rises in the blood the secretion and release of FSH slows down.
Decreased secretion of FSH may leads in the failure of gonadal function called hypogonadism the result is the cessation of reproductive cycles. Some conditions, that are common with diminished secretion of FSH are stated below:
- Polycystic Ovarian Syndrome : Irregular menstruation cycle, amenorrhea (absence of menstruation ) and ovulation-related infertility
- Kallmann syndrome : is a genetic condition, that leads in the failure to commence or the non-completion of puberty.
- Hypopituitarism : Decreased secretion of one or more hormones by the pituitary gland
- Hyperprolactinemia : The presence of high level of prolactin in blood.
- Gonadotrophin deficiency : Diminished gonadal functions.
Increased level of FSH leads to subfertility or infertility. Increased level of FSH may associates with following conditions :
- Premature menopause or Premature Ovarian Failure
- Poor ovarian reserve or Premature Ovarian Aging
- Gonadal dysgenesis : It is a congenital developmental disorder of the reproductive system characterized by underdeveloped and dysfunctioned gonads, that mainly composed of fibrous tissue. One of the example of gonadal dysgenesis is Turner syndrome or Monosomy X (absence of one X chromosome so the karyotype is 45,X )
- Certain forms of Congenital adrenal hyperplasia or CAH : It is an autosomal recessive diseases characterised by excessive or deficient production of sex steroids.
- Klinefelter syndrome : It is a genetic disorder of having 47 chromosomes and the karyotype is 47,XXY.
Lutenizing hormone : Lutenizing is another gonadotrophic hormone secreted from anterior pituitary.
Functions : An acute rise of LH known as preovulatory LH surge triggers ovulation and then the residual cells within the ovulated follicles proliferate to form corpus luteum during the luteal phase of the menstrual cycle or estrous cycle. Corpus luteum is a temporary endocrine structure, that secretes progesterone, estradiol and inhibition A.
High level of LH is normal in postmenopausal phase but not so in reproductive phase and may be the sign of following diseases (similar with FSH) :
- Premature menopause
- Gonadal dysgenesis, Turner syndrome
- Polycystic ovary syndrome
- Certain forms of congenital adrenal hyperplasia
Conditions with low LH secretions are as follows :
- Kallmann syndrome
- Female athlete triad
Maintaining proper balance of all these hormone is very important for women of all ages, elivated or diminished level of these hormones may lead to serious complications.