Seawater transfer down-regulates C-type natriuretic peptide-3 expression in prolactin-producing cells of Japanese eel: Negative correlation with plasma chloride concentration

• Published in: Molecular and cellular endocrinology Vol. 507; p. 110780
• Main Authors: Katayama, Yukitoshi, Wong, Marty Kwok-Shing, Kusakabe, Makoto, Fujio, Megumi, Takahashi, Natsuki, Yaguchi, Miku, Tsukada, Takehiro
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.05.2020
• Subjects: Acclimatization - genetics; Acclimatization - physiology; Anguilla - blood; Anguilla - genetics; Anguilla - metabolism; Animals; Chlorides - blood; CNP; Down-Regulation - genetics; Euryhaline fish; Freshwater adaptation; Lactotrophs - metabolism; Natriuretic Peptide, C-Type - genetics; Natriuretic Peptide, C-Type - metabolism; Osmolar Concentration; Osmoregulation; Osmoregulation - genetics; Prolactin - metabolism; Seawater - chemistry; Water-Electrolyte Balance - genetics; Osmoregulation; CNP; Freshwater adaptation; Euryhaline fish
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/j.mce.2020.110780

In euryhaline fishes, atrial and B-type natriuretic peptides are important hormones in hypo-osmoregulation, whereas osmoregulatory functions of C-type natriuretic peptides (CNPs) remain to be investigated. Although four CNP isoforms (CNP1-4) are mainly expressed in the brain, multiorgan expression of CNP3 was found in euryhaline Japanese eel, Anguilla japonica. Here we identified the CNP3-expressing cells and examined their response to osmotic stress in eel. CNP3 was expressed in several endocrine cells: prolactin-producing cells (pituitary), glucagon-producing cells (pancreas), and cardiomyocytes (heart). Pituitary CNP3 expression was the highest among organs and was decreased following seawater transfer, followed by a decrease in the freshwater-adaptating (hyper-osmoregulatory) hormone prolactin. We also showed the negative correlation between CNP3/prolactin expression in the pituitary and plasma Cl− concentration, but not for plasma Na+ concentration. These results suggest that CNP3 in the pituitary (and pancreas) plays a critical role in freshwater adaptation of euryhaline eel together with prolactin. •CNP3 was expressed in several endocrine cells: prolactin-producing cells, glucagon-producing cells, and cardiomyocytes.•Pituitary CNP3 was decreased by seawater transfer, followed by decrease in the freshwater-adaptating hormone prolactin.•CNP3/prolactin expression in the pituitary is negatively correlated with plasma Cl- concentration.