LH-Luteinizing Hormone

Luteinizing Hormone (LH)

The LH and FSH are from the pituitary both are secreted under the effect of gonadotropin releasing hormone (GnRH).
Puberty does not set in until the pulsatile secretion of LHRH is started by the hypothalamus.
The fundamental change during puberty is that the hypothalamic inhibition if LHRH is reducted.

This hormone is also known as Interstitial Cells Stimulating Hormone (ICSH).
It causes the final maturation of Graafian follicle and stimulates ovulation.
Stimulates secretion of estrogen by the theca and granulosa cells.
It helps in the formation and development of corpus luteum for luteinization of cells.
In conjunction with luteotropic hormone (LTH), it is concerned with the production of estrogen & progesterone by the corpus luteum.
In the ovary it can stimulate the non-germinal elements, which contain the interstitial cells to produce the androgens, androstenedione, DHEA and testosterone.

It is necessary for final follicular growth and ovulation.
Without this hormone, even though large quantities of FSH are available, the follicle will not progress to the stage of ovulation.
LH acts synergistically with FSH to cause rapid swelling of the follicle shortly before ovulation.
Large amount of LH called ovulatory surge is secreted by the pituitary during the day immediately preceding ovulation.

Testosterone is produced by the interstitial cells of Leydig only when the testes are stimulated by LH from the pituitary gland.
The quantity of testosterone secreted varies approximately in proportion to the amount of LH available.
Thus in males, LH stimulates the development and functional activity of Leydig cells (interstitial) and consequently testicular androgen.

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