Extra-pituitary action of gonadotropin releasing hormone: possible application |
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Authors: | Chandana Das |
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Institution: | (1) Department of Biochemistry, All India Institute of Medical Sciences, 110 029 New Delhi, India |
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Abstract: | Chronic administration of a potent gonadotropin releasing hormone inhibits ovulation in women. The suppression of gonadal
function during long term treatment with the GnRH analogues is ascribable to inhibition of gonadotropin secretion caused by
the down regulatory action of the decapeptide at the pituitary level. Reduced progesterone production with premature onset
of menstruation has been observed in women injected with the agonist during the midluteal phase. The decapeptide however,
has no effect onin vitro human ovarian steroidogenesis. Specific receptors for GnRH have been located on rodent ovarian cells, but corpora lutea of
rhesus monkey and human ovaries seem to lack these receptors. The luteolytic effect in women thus appears to be central in
origin and not a direct effect on the corpus luteum. Recently, a superactive agonist of GnRH given around the peri-implantation
period has been shown to terminate pregnancy in baboons. Monoclonal antibodies against GnRH administered during the same period
in a fertile cycle also abrogated pregnancy in these animals. Using immuno-enzymatic techniques GnRH has been localized on
the placenta. GnRH also exerts a stimulatory effect on hCG production by the placental villi maintained in culture. Addition
of anti-luteinizing hormone releasing hormone antibodies blocks this effect completely. It seems that placenta is the only
other tissue besides the pituitary where GnRH has probably a regulatory role in the human female. |
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Keywords: | GnRH pituitary ovary luteolysis abortion placenta |
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