French–American physiologist (1924–)

Guillemin was educated at the universities of Dijon (his native city), Lyons, and Montreal, where he gained his PhD in physiology and experimental medicine in 1953. The same year he moved to America to join the staff of the Baylor University Medical School, Houston. In 1970 Guillemin joined the staff of the Salk Institute in La Jolla, California, where he remained until 1989, when he moved to the Whittier Institute for Diabetes and Endocrinology, La Jolla, becoming its director in 1993.

Early in his career Guillemin decided to work on the hypothesis of Geoffrey Harris that the pituitary gland is under the control of hormones produced by the hypothalamus. As the anterior pituitary secretes a number of hormones it was far from clear which to begin with. He eventually decided to search for the hypothalamic factor that controls the release of the adrenocorticotrophic hormone (ACTH) from the pituitary – it is known as the corticotrophic releasing factor (CRF). As it turned out, this was an unfortunate choice for after seven years Guillemin had nothing to show for his not inconsiderable efforts. Guillemin then worked for a further six years fruitlessly searching for the thyrotropin releasing factor (TRF), exposing him to skepticism from many other workers in the endocrine field.

The main difficulty was that such hormones were present in very small quantities. When Guillemin finally did succeed in 1968 in isolating one milligram of TRF it had come from 5 million sheep's hypothalami. It turned out to be a small, relatively simple tripeptide, easy to synthesize. The development of the radioimmunoassay method for the detection of minute quantities by Rosalyn Yalow was also of considerable help. Other successes quickly followed. Andrew Schally isolated the luteinizing-hormone releasing factor in 1971 and Guillemin in 1972 succeeded with somatostatin, which controls the release of the growth hormone.

In 1977 Guillemin shared the Nobel Prize for physiology or medicine with Schally and Yalow.

For more information on Roger Charles Louis Guillemin, visit Britannica.com.

(gēyəmăN') , 1924–, French-American physiologist, b. Dijon, France. Educated in France, he fought for the resistance during World War II. He taught primarily at Baylor Univ. (1953–70), until he became a researcher at the Salk Institute for Biological Studies (Calif.). Guillemin isolated and synthesized the hormones produced by the hypothalamus gland. These hormones regulate the pituitary gland, which governs other glands that regulate such body functions as reproduction and emotional responses. He also discovered endorphins, a class of hormonal substances. His work added new dimensions to the study of the brain's control over the body's chemistry. In 1977, Guillemin shared the Nobel Prize in Physiology or Medicine with Andrew Schally and Rosalyn Yalow.

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