A team headed by Nobel laureate Roger Guillemin has found and reproduced a chemical that appears to be biologically identical to the long-sought brain compound that triggers the release of the human growth hormone.
The researchers said that the advance could have practical applications in the treatment of dwarfism, diabetes, severe burns, and other medical problems.
A statement from the prestigious Salk Institute for Biological Studies in La Jolla, Calif., where the research was conducted, said that the discovery also has "profound implications in the field of animal husbandry," providing a potential means of regulating the growth of farm animals.
The Salk team said that it had identified the basic building blocks of a chemical that has the same properties as the elusive growth-hormone releasing factor (GRF).
GRF, produced in the brain's hypothalamus, sends messages to the pituitary gland that direct the release of growth hormone. Growth hormone helps control overall body growth, the formation of connective tissue, and protein formation.
Guillemin and his group sought for years to extract GRF from the brain, but could not accumulate enough for complete analysis. By a combination of luck and scientific sharing, he obtained the chemical from a French patient with a pancreatic tumor that caused acromegaly, or giant hands, feet and face from the overproduction of growth hormone.
Tests indicated that the compound appears to be "biologically identical" to the brain GRF, the French-born scientist said in a telephone interview from Paris.
Imbalances in the production of growth hormone can contribute to short stature, or pituitary dwarfism in which the body has normal proportions but is grossly undersized. A child may be born with the problem or acquire it through head injuries or infection.
Guillemin said that clinical study of the releasing factor may help many victims as well as those suffering from some forms of diabetes or extensive burns.
He said that some forms of diabetes are believed to involve imbalances in the production of growth hormone and might benefit from GRF. Wounds, broken bones and burns, which involve regrowth of connective tissue, might be stimulated to heal faster.
At this point, however, the chemical has only been produced in small amounts in the laboratory and has not been tested in humans. Guillemin said that he expected large amounts of the chemical could be produced through gene-splicing or "recombinant DNA" technology. He will apply soon to the Food and Drug Administration for permission to begin human testing.
Human testing is under way on a man-made form of human growth hormone produced through the new genetic technique. Until now, the hormone could only be obtained in tiny amounts from the pituitary glands of human cadavers.
Guillemin said that availability of the releasing factor would provide an "alternative approach" to treating growth problems, adding that in some cases it may be preferable to stimulate the natural production of the hormone rather than replace the hormone. He said that the growth hormone trigger might be cheaper to make because it is less fragile than the growth hormone.
Dr. Lynn Loriaux, clinical director of the National Institute of Child Health and Human Development, which funded part of the research, agreed that it could prove "extremely important" in diagnosing and treating growth problems. He cautioned that "all remains to be seen," but said early returns could be available "within a few years for sure."
In terms of basic research, Guillemin, who shared the 1977 Nobel Prize for medicine, said that the research "closes the circle" in the long search for brain chemicals that control the secretion of major hormones from the pituitary gland.
Twenty-five years ago, he and other researchers had predicted the existence of four major releasing factors in the hypothalamus area of the brain. These factors would trigger the hormones regulating basic human functions like sex, stress, the thyroid gland, and growth.
Growth hormone releasing factor is the last of the four to be reproduced. The findings, which are being published in the Nov. 5 issue of Science magazine, represent the culmination of more than a decade of work at Guillemin's laboratory.