June 26, 2008


Scientists in Iowa looking at natural way to stimulate growth hormone production


A team of scientists in Iowa are studying how the release of hormones in livestock can lead to greater efficiency of growth and meat quality.


With funding from USDA's Cooperative State Research, Education, and Extension Service's (CSREES) National Research Initiative (NRI) programme, scientists examined how secretion of growth hormones in individual cells is induced.


Growth hormones (GH) control the growth, metabolism and deposition of muscle and fat in mammals and poultry as well as growth in fish.


Growth hormones are secreted by cells called somatotropes that are located in the pituitary gland in the brain. These cells are controlled by other hormones called GH-releasing hormones.


The scientists are finding out how the somatotropes can be regulated to improve the quality of animal products.


Colin Scanes, Lloyd Anderson and colleagues at the Iowa State University examined calcium ion sensitivity to GH-releasing hormones and have already determined that one GH-releasing hormone, called gonadotropin-releasing hormone (GnRH), expressed calcium ion sensitivity in 40 percent of somatotropes.


The sensitivity to calcium ion may be one of the pathways to reflect how these cells communicate in order to release the hormones.


Scientists know that GnRH stimulates the release of growth hormones in several important fish species, including tilapia and rainbow trout. The findings may lead to improvements in management and feeding strategies that aim for natural release of growth hormones in animals. 

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