Leid Endocrine Pharmacology 3 Flashcards
What releases GnRH?
The hypothalamus. It acts on the gonadotropes in the anterior pituitary to secrete LH and FHS. These act on both the ovaries and the testes. LH causes secretion of progesterone and testosterone, while FSH causes secretion of estrogen and spermatogenic factors.
When LH acts on the testes, what happens?
LH acts on the Leydig cells, which secrete testosterone. Testosterone has several effects, one of which is to act on germ cells to initiate spermatogenesis along with other spermatogenic factors. Testosterone has negative feedback on the anterior pituitary and the hypothalamus.
LH also has a trophic effect on the male gonads, and so inhibition of LH (often caused from too much negative feedback by testosterone) causes them to shrink.
When FSH acts on the testes, what happens?
FSH acts on the Sertoli cells, which then produce spermatogenic factors and Inhibit B. Inhibit B has negative feedback on both the anterior pituitary and the hypothalamus.
What does release of GnRH cause?
It depends on the way it is released. If it is pulsatile, then the anterior pituitary will be stimulated to produce LH and FSH.
If the release of GNRH is constant, then GnRH receptors on the gonadotropes will be desensitized and the release of FSH and LH will be decreased.
Explain the reasoning behind chemical castration and the treatment of both prostate cancer and endometriosis:
Agonist-induced desensitization is exploited, involving GnRH and it’s receptors.
What is required for initiation of spermatogenesis? Maintenance?
Both FSH and T are required for initiation.
Only T is required for maintenance.
What are the effects of Inhibin B?
Inhibit B acts on the anterior pituitary to inhibit production of FSH (not much of an effect of LH). It also acts on the hypothalamus to inhibit production of GnRH.
What hormone causes an anabolic effect on skeletal muscle?
Testosterone
In females, what does FSH and LH cause in the ovaries?
FSH acts on the granulosa cells to cause estrogen production and secretion
LH causes follicular maturation and ovulation, and then progesterone secretion by corpus luteum. Progesterone is secreted after ovulation and during early pregnancy by the corpus luteum.
What effect does estrogen have in a female?
Estrogen is secreted by the granulosa cells.
It has a part in follicular maturation, endometrial proliferation, and secondary sex characteristics.
What effect does progesterone have in a female?
Progesterone is secreted by the corpus luteum.
It causes endometrial differentiation in the latter half of the cycle, and has a part in secondary sex characteristics.
Where are the granulosa cells located?
They are located in the ovaries directly surrounding the egg. Later, thecal cells surround them as the cycle progresses.
Where do contraceptives act?
Estrogen
Estrogen & Progesterone
Progesterone
All of these contraceptives act via negative feedback on the anterior pituitary to inhibit the LH surge mid-cycle.
What do aromatase inhibitors do?
Block the conversion of testosterone to estrogen.
What are the effects of GnRH agonists and antagonists in a female?
Both GnRh agonists and antagonists would decrease the amount of FSH and LH being released.
