ABSTRACT
In this chapter, we focus on recent advances in the endocrinology of the renin-angiotensin system (RAS), natriuretic peptide (NP) family, guanylin (GN) family, and adrenomedulin (AM) family in the eel, particularly in regard to their role in osmoregulation. Eels, as well as other migratory and esturarine species such as salmonids, fl ounders, etc., are categorized as euryhaline teleosts, which can tolerate a wide range of salinity fl uctuations,
1Department of Anatomy, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan. E-mail: tsukada@jichi.ac.jp 2Laboratory of Physiology, Department of Marine Biosciences, Atmosphere and Ocean Research Institute, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan. E-mail: martywong@aori.u-tokyo.ac.jp 3Ushimado Marine Institute, Faculty of Science, Okayama University, 130-17 Kashino, Ushimado, Okayama 701-4303, Japan. E-mail: ogoshi-m@cc.okayama-u.ac.jp 4Department of Fisheries & Wildlife, Michigan State University, 158 Giltner Hall, East Lansing, MI 48824, USA. E-mail: shinya.yuge@gmail.com *Corresponding author
in contrast to stenohaline teleosts that exhibit a narrow range of salinity tolerance. The Anguillid eels have been used as experimental models to study osmoregulation since the early 20th century (Chester-Jones et al. 1966, Maetz and Skadhauge 1968, Oide and Utida 1968), and their versatile ability to acclimate to both freshwater (FW) and seawater (SW) enables researchers to examine their physiology during short-term and long-term salinity adaptation. In addition, surgical operations such as cannulation of blood vessels, intestine, urinary bladder, etc., and ablation of tissues and organs (e.g., hypophysectomy) have allowed researchers to conduct real-time monitoring of physiological parameters such as ions and hormone levels, drinking rate, blood pressure, heart rate, branchial and gastrointestinal activities (e.g., epithelial ion and water transport), and urine fl ow after environmental transfer or hormone treatment.
