Luteinizing Hormone and FSH

[hieu]

Hey,

Could someone please clear this up for me? I'm a little confused on whether or not LH or FSH directly produces estrogen and progesterone. I know that LH is important in causing ovulation but is there more to it? Also FSH causing maturation of the Follicle so are they indirectly involved in estrogen production through the follicle?

thanks

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[Tenebrus]

FSH stimulates the initial development of the follicle; LH will then stimulate the follicle to secrete androgens, which will be converted into estradiol (estrogen) in the presence of FSH.

So basically they're both necessary for estrogen production.

As for ovulation, estrogen in low concentrations (like during initial release) will inhibit the secretion of further LH. Just prior to ovulation estrogen secretion increases dramatically; this instead stimulates the secretion of LH, causing the luteal surge. LH is responsible for ovulation, and will trigger secretion of more estrogen in turn. Basically LH in low concentrations will inhibit, but in high concentrations stimulates LH (don't ask me how exactly that works lol).

I hope that clears things up, female reproductive system took me a while to understand...

 

[Ace-Co-A]

In response to the hypothalamic hormone Gonadotropin-releasing Hormone (GnRH), the anterior pituitary gland releases the hormones follice-stimulating hormone (FSH) and luteinizing hormone (LH). FSH is associated with regulating the secretion of estrogen (especially estradiol). FSH stimulates follicle development and regulates the meiotic divisions of the oocyte. A peak in estrogen levels proceeds a peak in LH, which causes ovulation (something like day 13-14 of ovarian cycle). After ovulation, the corpus luteum (literally, "yellow body") secretes estradiol and progestins (esp. progesterone), which are needed to maintain the integrity of the uterine lining (called the endometrium). If fertilization occurs, the corpus luteum continues to secrete estrogens and progestins to maintain the pregnancy. If fertilization does not occur, then the estrogen and progesterone levels decrease; the resulting deficiency of nutrients to the endometrium (i.e., due to vasoconstriction to the point of complete closure, etc.) causes these top tissues to be shed (this is called menstruation).

A succinct answer of your question: FSH and LH are both tropic hormones that regulate the secretion of estrogens and progestins. They act synergistically and are in turn regulated by the levels of estrogen. If estrogen levels are low, the release of FSH and LH from the APG is inhibited (negative feedback). However, increased levels of estrogens and progestins later in the cycle stimulate the production of FSH and LH, in a postive feedback loop.

(Please let me know if anything isn't clear!)

 

[hieu]

Thank y'all so much. That definitely cleared things up. One quick question though. So progesterone prior to the ovulation is produced by the interaction of LH and FSH just like the estrogen?

 

[Ace-Co-A]

The levels of progestins prior to ovulation are relatively low (and, as far as I know) inconsequential.