OVARIAN HORMONES

Two important ovarian hormones

• Estrogen

• Progesterone

ESTROGEN:

• Primarily secreted by granulosa cells of ovarian follicles, corpus luteum & placenta.

• 18-Carbon steroids

• Naturally occurring estrogens – 

– Estradiol, Estrone & Estriol

• Estradiol 

– Major estrogen secreted by ovary in normal adult women.

• Estrone

– Major in postmenopausal women

• Estriol

– Major in pregnant women

Major physiological actions of estrogen:

1. In Sex organs:

• Brings pubertal changes in female.

• Growth of uterus, fallopian tube & vagina.

• Vaginal epithelium gets thickened, stratified and cornified.

• Endometrium proliferation in preovulatory phase.

• Estrogen sensitizes uterus to oxytocin.

2. Secondary sexual character development: 

• Growth of breast-proliferation of duct & stroma

• Fat accumulation.

• Appearance of pubic & axillary hair.

• Feminine body contours & behaviour influenced.

• Acne common in girls at puberty 

– Due to androgens.

3. Metabolic effects:

• Anabolic

• Promotes fusion of epiphysis

• Maintain bone mass by reducing bone resorption.

• Promote positive calcium balance by inducing renal 1α-hydroxylase

• Cause salt & water retention.

• Decrease LDL while increasing HDL & triglycerides

– Atherosclerosis is rare before menopause.

• Blood coagulability increased –

– Due to increased synthesis of factor II, VII, IX & X.

• Increase bile lithogenicity –

– By increasing cholesterol secretion & decreasing bile secretion.

PROGESTERONE:

• 21 carbon steroid.

• Secreted by corpus luteum, placenta, & follicle (small amounts).

Major physiological actions:

1. In Uterus

• Secretory changes in estrogen-primed endometrium.

• Decrease uterus sensitivity to oxytocin.

• Lack of progesterone support (Progesterone withdrawal).

• Causes mucosal shedding & bleeding during menstruation.

2. In Cervix

• Converts watery cervical secretion induced by estrogen to viscid & scanty.

• Hostile to sperm penetration.

3. In Vagina

• Induces pregnancy like changes in vaginal mucosa

• Leukocyte infiltration of cornified epithelium.

4. In Breast:

• Causes proliferation of mammary glands acini.

• Prepares breast for lactation along with estrogen.

5. On CNS:

• Sedative effect

6. On Body temperature:

• Causes a slight (0.5°c) rise in body temperature.

7. On Metabolism

• Raises LDL 

• Lowers HDL

• Impaired glucose tolerance.

8. On Pituitary

• Inhibits LH secretion by feedback inhibition – “Anovulatory action”

OTHER OVARIAN HORMONES:

1. Inhibin:

• Secreted by granulosa cells & corpus luteum in ovary & Sertoli cells in males.

• Inhibits FSH secretion in feedback manner.

2. Activin:

• Secreted by granulosa cells in females & Sertoli cells in males.

• Stimulates FSH secretion.

3. Relaxin:

• Secreted by corpus luteum in ovary & from placenta.

• Structurally similar to insulin & Insulin-like Growth Factor (IGF).

• Relaxes symphysis & sacroiliac joints during pregnancy.

• Helps in cervical ripening.