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Chapter 56 GnRH and GnRH Analogs
Stephanie J. Estes, MD, FACOG
❍ What is the olfactory placode?
The olfactory placode is a plate of ectoderm from which the olfactory organ and gonadotropin-releasing hormone
(GnRH) neurons originate.
❍ How many cells migrated from olfactory area will produce GnRH?
1000 to 3000.
❍ What syndrome develops as a result of olfactory axons and GnRH neurons failure to migrate from the
olfactory placode?
Kallmann syndrome.
❍ What is the primary unique symptom of Kallmann syndrome?
Anosmia (or hyposmia).
❍ What is the most common mode of transmission of Kallmann syndrome?
X-linked. Transmission can also be autosomal dominant or autosomal recessive.
❍ What is GnRH and where is it produced?
GnRH is gonadotropin-releasing hormone that is produced by the arcuate nucleus of the hypothalamus.
❍ What is the half-life of GnRH?
2 to 4 minutes.
❍ What is the cause of the short half-life of GnRH?
The short half-life of GnRH is due to rapid cleavage of the bonds between amino acids 5 to 6, 6 to 7, and 9 to 10.
❍ What are the modes of administration of GnRH agonists?
IV, SQ, nasal spray, sustained-release implants, and IM injections of biodegradable microspheres. The GnRH
analogues cannot escape destruction if administered orally.