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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 • • • • 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.