ISU Study First to Show How Endrocrine Cells Release Hormones

May 6th, 2002

AMES, Iowa — An Iowa State University study is the first to show how endocrine cells release hormones in the body.

"It's a new finding on how the cell operates," said Lloyd Anderson, a distinguished professor of animal science. "The results provide a new interpretation on how hormones are secreted from an endocrine cell."

Knowing how cells secrete growth hormone may open up new ways to address growth problems in children and improve the health of the elderly, Anderson said.

The research results were the cover story of the March issue of Endocrinology, the journal of The Endocrine Society.

Endocrine glands secrete hormones that regulate growth and metabolism in people and animals. Anderson and his colleagues studied the release of growth hormone from a pig's pituitary gland.

The researchers used an atomic force microscope to scan the outer membrane of live pituitary cells. The membrane's surface is covered with pits. "Inside the pits are depressions that now have been identified as fusion pores, which act like valves for the release of hormones," Anderson said.

Inside the cell, vesicles - bubbles that carry compounds to be secreted - dock into the fusion pores. When the researchers stimulate the cells, the pores get larger and deeper, resulting in the release of the hormone to the outside of the cell. The vesicles detach from the pores and go off to replenish themselves.

"Now that we've found it happening in endocrine cells and in other secretory cells, we're becoming aware of the universality of the process," Anderson said. "We believe it's a common way that cells secrete chemicals. We think it will become a fundamental part of biology."

It also may help address problems in humans and animals.

"Some short-statured kids now take hormone injections to stimulate growth. Our aging population experiences loss of muscle tone and the thinning of their skin, which could be addressed by stimulating modest releases of growth hormone," he said.

For livestock, the information may lead to new methods to stimulate the pituitary, improving the speed and efficiency of animal growth, Anderson said.

Anderson, who studies the cellular mechanisms that regulate growth and reproduction in farm animals, plans to continue the research with cells from older animals. The cells in the recent research were from newborn pigs. "We want to know whether cells from older animals behave differently than those in younger animals," he said.


Lloyd Anderson, Animal Science, (515) 294-5540

Brian Meyer, Agriculture Communications, (515) 294-5616