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Growth Hormone and Recombinant
Bovine Growth Hormone
Stevie
Growth Hormone
• Protein hormone made of ~ 190 amino acids
• Made in Anterior Pituitary by somatotroph
cells
Direct Effects of GH
• Binds to adipocytes and causes them to break
down triglycerides and prevents them from
accumulating fat in the blood
• Releases insulin-like growth factor-1 (IGF-1)
Indirect Effects of GH
• Stimulates:
– Cartilage cells (chrondrocytes) growth
– Myoblasts growth and differentiation
– Amino Acid uptake
– Protein synthesis
Other Effects
• Keeps blood glucose at healthy levels
• Prevents insulin from absorbing glucose in
tissue
• Causes creation of glucose in the liver
• In mature cows, it stimulates lactation
GH Secretion
• Growth Hormone-Releasing Hormone: causes
production and release of GH
• Somatostatin: inhibits release of GH
• Grehlin: secreted from stomach, binds to
somatotrophs and causes secretion of GH
Negative Feedback Loop
• If blood levels of IGF-1 are too high,
somatotrophs are suppressed and
somatostatin is released
• GH also circles back to hypothalamus and
inhibits release
• Scientists believe GH has an autocrine effect
on somatostatin
• This leads to GH inhibition
Recombinant Bovine Growth Hormone
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Increases milk production by 10-15%
Regulates efficiency of feed conversion to milk
rBGH mimics the effects of growth hormone
Growth Hormone is a naturally occurring
hormone produced in the anterior pituitary
How rBGH works
• Created using recombinant DNA technology
• The gene sequence for this hormone is
injected into e. coli
• E. coli then produces GH
• This is purified and injected into dairy cows
• Broken down once it enters digestive system
• Called Posilac
How rBGH works
• Cows lactate 305 days after calving, but their
peak in lactation is between 45-90 days
• Farmers administer rBGH just before peak
lactation
• rBGH prevents mammary cell death
– Fat is broken down and sent to mammary cells
References
• "Bovine Somatotropin." Wikipedia. Wikimedia
Foundation, 09 Jan. 2014. Web. 14 Sept. 2014.
• Bowen, R. "Growth Hormone." Growth
Hormone. Colorado State, 24 Dec. 2006. Web.
14 Sept. 2014.