Inhibin and Actvin Flashcards
Where is activin made?
Activin is produced in the gonads, pituitary gland, placenta, and other organs
What are the roles of activin?
In the ovarian follicle, activin increases FSH binding and FSH-induced aromatization. It participates in androgen synthesis enhancing LH action in the ovary and testis. In the male, activin enhances spermatogenesis.
Activin is strongly expressed in wounded skin, and overexpression of activin in epidermis of transgenic mice improves wound healing and enhances scar formation. Its action in wound repair and skin morphogenesis is through stimulation of keratinocytes and stromal cells in a dose-dependent manner.
Activin also regulates the morphogenesis of branching organs such as the prostate, lung, and especially kidney. Activin A increased the expression level of type-I collagen suggesting that activin A acts as a potent activator of fibroblasts.
Recent results suggest activin A plays a role specifically in lung cancer metastasis and possibly the metastasis of other forms of cancer
Lack of activin during development results in what?
neural developmental defects.
What does inhibin do in males and females?
In both females and males, inhibin inhibits FSH production. Inhibin does not inhibit the secretion of GnRH from the hypothalamus. However, the overall mechanism differs between the sexes:
What are the effects of inhibin in females?
FSH stimulates the secretion of inhibin from the granulosa cells of the ovarian follicles in the ovaries. In turn, inhibin suppresses FSH.
Inhibin B reaches a peak in the early- to mid-follicular phase, and a second peak at ovulation.
Inhibin A reaches its peak in the mid-luteal phase.
T or F. Inhibin secretion is diminished by GnRH, and enhanced by insulin-like growth factor-1 (IGF-1).
T.
Where is inhibin made in men?
It is secreted from the Sertoli cells, located in the seminiferous tubules inside the testes. Androgens stimulate inhibin production; this protein may also help to locally regulate spermatogenesis.
Clinical use of Inhibin A?
Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16–18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is suggestive of the presence of a fetus with Down syndrome. As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.
It also has been used as a marker for ovarian cancer
Clinical use of Inhibin B?
Inhibin B may be used as a marker of spermatogenesis function and male infertility. The mean serum inhibin B level is significantly higher among fertile men (approximately 140 pg/mL) than in infertile men (approximately 80 pg/mL).
