A Tribute to Erika M. Plisetskaya: New Insights on the Function and Evolution of Gastroenteropancreatic Hormones. Introduction to the Symposium(1).

Since the discovery of the first hormone, secretin, from the gastrointestinal tract by Bayliss and Starling in 1902, our knowledge of chemical mediators produced by the gastroenteropancreatic (GEP) system has grown considerably. The emergence of each new experimental approach ushered in a wave of new information. The latest developments in molecular biological approaches have and will continue to provide many important insights into hormone biology. Today, we know that the GEP cell feature of amine precursor uptake and decarboxylation (APUD) is shared by many other cell types (Norris, 1997); in fact, hormones secreted by the GEP also are secreted by cells of the nervous system, leading to the notion of a "brain-gut" distribution of hormones that makes the distinction between the endocrine system and nervous system no longer tenable (Thorndyke and Falkmer, 1985). We also now know that many GEP/neural hormones exist in a variety of molecular forms, sometimes co-localized with other factors, that modulate a vast array of functions in target cells that may be either distant or near to the site of secretion (see Holmgren, 1989). It is indeed interesting that the GEP system, the system that gave us the term "hormone" (Starling, 1905), now forces us to re-examine what a hormone is.

This symposium was designed to advance such a re-examination by bringing together GEP researchers whose recent work has provided new information on several critical issues that face hormone biology; among this information includes insights into the following topics: 1) origins of hormones, 2) hormone biosynthesis--from gene to bioactive peptide, 3) hormone structure-function relationships, and 4) ligand-receptor interactions. The comparative approaches employed by the participants uniquely posture this symposium to provide an integrated, up-to-date view about the evolution of the GEP system in animals.

CONTRIBUTIONS OF ERIKA M. PLISETSKAYA TO THE FIELD OF GASTROENTEROPANCREATIC PHYSIOLOGY

This symposium was held in honor of Dr. Erika M. Plisetskaya. Dr. Plisetskaya's research, recounted in over 160 papers, laid the framework for much of our current understanding about the evolution of GEP hormones and of metabolic/growth control systems. Dr. Plisetskaya's scientific career has spanned over 40 years. The first twenty-five of these years she spent as a scientist working in the Soviet Union of Socialist Republics. In 1979, she immigrated to the United States. During her career, she had the opportunity of collaborating and interacting with two outstanding comparative endocrinologists, Dr. Leo Leibson in Russia and Dr. Aubrey Gorbman in the United States. During the past seventeen years while in the USA, Dr. Plisetskaya's research activity has nearly doubled (Fig. 1).

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Dr. Plisetskaya has made significant contributions to our understanding of the GEP system through the use of comparative and integrative approaches. These contributions occurred, in part, because she focused on evolutionarily important groups of animals that had either not been studied or studied very little in respect to the metabolic role of pancreatic hormones belonging to insulin, glucagon, somatostatin and pancreatic peptide superfamilies. Her experimental models have included bivalve molluscs, slugs, lancelet, hagfish, lampreys, numerous groups of teleost fish, including scorpion fish, several species of salmonids and catfish, frogs, turtles, chicken, and mammals (rats). As examples, she worked on lampreys in the early sixties, molluscs and lancelet in the early seventies, and teleosts in the early eighties.

Therefore, Dr. Plisetskaya and the field of GEP hormones evolved, grew and expanded together. In 1975, she published a book entitled, Hormonal Regulation of Carbohydrate Metabolism in Lower Vertebrates, which thoroughly covered the field from its very beginning and for the next 50 years. Times have changed, and the field of GEP hormones and peptides has exploded. Dr. Plisetskaya feels that she would not be able to cover the same field for the last 25 years in a single book because of all the new knowledge that has become available (see the Sower et al. paper from this symposium). She has tried to compensate and has written more narrowly focused reviews. As an example, one of her most memorable recent reviews in this field was entitled "Glucagon and Glucagon-like peptides in Fishes" (Plisetskaya and Mommsen, 1996).