Question

Describe the negative feedback mechanism that follicle stimulating hormone and Luteinizing hormones have on the male and female gonads.  For full credit make sure that you include releasing and inhibiting hormones.

Answer 1

Females

Three systems are involved

Hypothalamus, pituitary and the ovaries(gonads)

FSH and LH system also called ''two cell theory)

When there is deficiency of estrogen and progesterone in the body there occurs negative feedback on the hypothalamus which releases gonadotropin releasing hormone (Gnrh)

Gnrh acts on the pituitary to release FSH and LH

FSH acts on the granulosa cell which helps in development of follicle and release estrogen

LH acts on the theca cell which first By LH surge causes ovulation, helps in both estrogen and progesterone production.

When there is no fertilization the follicle starts dissapearing, estrogen decreases which then causes negative feedback, similarly corpus luteum is formed as there is no fertilization ;it becomes corpus albicans, decreases progesterone and hence causes negative feedback. Estrogen is the main hormone for negative feedback. As there is negative feedback on hypothalamus, next cycle with increasing Gnrh begins again.

MALES

Similarly in males , (estradiol) estrogen causes negative feedback on hypothalamus, releasing Gnrh, acting on anterior pituitary to realease FSH and LH.

FSH acts on the Sertoli cells to cause spermatogenesis.( Similar to follicle development in females) and also produces inhibin B by Sertoli cells. Which causes negative feedback on anterior pituitary.

And LH acts on the Leydig cell to produce testosterone . Decreasing testosterone also causes negative feedback on anterior pituitary as well as hypothalamus .

Testosterone in peripheral fat by aromatization converts into estrogen which causes negative feedback on hypothalamus.

NE,NPY,Leptin provide positive feedback for Gnrh release

And Beta endorphins, DA, IL-1, GABA provide negative feedback on Gnrh release