Cystorelin

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Cystorelin

• Reproduction Physiology 434
• Danielle James
• Angie Ahlstrom
• Elsa Ludwig
• Rachel Leisemann

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What is it?

• GnRH
• Made in the laboratory
• Chemical Class is a polypeptide
• Empirical formula C55H75N17O13

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Reproductive Uses

• Treatment of ovarian follicular cysts
• Induction of ovulation in mature follicles
• Used twice in standard ovsynch for cows

Follicular cyst on cows ovary
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Hormone Action

• Cause release of LH from Anterior Pituitary
• LH ovulates or luteinizes ovarian follicular
  cysts or induces ovulation of a follicle

Follicle about to ovulate
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Mechanism of Action

• Works through calcium second messenger system
• GnRH binds to receptor in plasma membrane of
  anterior pituitary cell
• Binding causes receptor to associate with
  G-protein that associates with PLC
• PLC catalyzes cleavage of phosphotidylinositol in
  plasma membrane
• IP3 portion into cytoplasm, DAG in membrane

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Mechanism of Action

• IP3 reacts with receptor on ER
• Releases calcium from ER into cytoplasm
• DAG activated PKC
• Phosphorylates calcium channels calcium into
  cell
• Increased calcium causes LH granules to move
  along cytoskeleton to plasma membrane
• Fuse with plasma membrane
• LH released into extracellular space, blood stream

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Side Effects?

• No adverse side effects
• Does not cause irritation at site of IM injection