diyamirzah
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UW mentions that GnRH agonists should be given in idiopathic precocious puberty to inhibit estrogen ....to avoid premature closure of epiphysis.....i couldnt understand the exact mechanism, i think GnRH should stimulate estrogen release... can any body explain...???
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| srf
Forum Guru
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it blocks the receptors.
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| mariam
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GnRH analogues stimulate the pituitary in a constant fasion rather than in pulsatile fasion as the normal GnRH.. this will make the pituitary tired which leads to downregulation of the pituitary and inhibition of the Axis (hypoth >> pituit >> ovar >> endom ) which gives more time for the female to complete her growth before closure of the epiphysis.
i hope this can help
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| diyamirzah
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thank you mariam, its clear now.
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| srf
Forum Guru
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Gnrh analogues occupies pituitary receptors constantly . this leads to desensitition & thereby inhibition or blocking of pituitary receptors.the number of receptors do not decreases or downregulated .this is what lippincott pharm explains.
I may be wrong in my understanding.I will highly appreciates further clerification from mariam.
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| achilles
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i'll go with mariam...i got to know this concept during one of my kaplan lectures ( i dont know which one but just remember the concept ).
GnRH is released in a pulsatile fashion normally to maintain the responsiveness of the receptors. GnRH analogues act in a continuous fashion on the receptors and downregulate them and thus the hypothalamus-pituitary axis is interuppted and the girl will get time to complete her growth before the epiphysis close.
the number of receptors are not decreased but there is downregulation of receptors. and this is the reason why there is a flare up effect initially which is followed by downregulation of the receptors and thus a decrease in levels of hormones.
blocking a receptors would be the mechanism of action of an antagonist and not an analogue. this is what i know but its been some time since i read this. if anyone else can vouch for this pls do so.
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| aimhigh
Forum Elite
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Achilles and Mariam were right about this: it's all about pulsatile nature and the downregulation of constant impact of GnRH.
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