title: Profiles of hypothalamus-pituitary-interrenal axis gene expression in the parr and smolt stages of rainbow trout, Oncorhynchus mykiss: effects of recombinant aquaporin 3 and seawater acclimation.
abstract: The objective of this investigation was to quantify how the hypothalamus-pituitary-interrenal (HPI) axis in the rainbow trout, Oncorhynchus mykiss (parr/smolt), responds to salinity changes during transfer from freshwater (FW) to seawater (SW) and recombinant aquaporin 3 (rAQP3) injection. mRNA expression levels of HPI axis genes [corticotropic-releasing hormone (CRH) and adrenocorticotropic hormone (ACTHα and ACTHβ)] significantly increased when the fish were transferred from FW to SW (parr: 16.4-, 13.2-, 21.4-, and 11.9-fold higher than FW; smolt: 2.3-, 2.7-, 13.6-, and 6.2-fold higher than FW, respectively). Furthermore, and the plasma ACTH, Na(+), Cl(-), and K(+) levels were the highest at 50% SW. Moreover, these parameters were significantly lower in the rAQP3-treated group than those in the control (parr: 2.0-, 2.4-, 2.1-, and 2.0-fold lower than SW; smolt: 4.2-, 1.9-, 2.4-, and 2.3-fold lower than SW, respectively). Hence, HPI axis genes may play a role in SW adaptation during migration from FW to SW environments. We showed that there was a negative correlation between rAQP3, HPI axis genes, and ion levels when the fish were transferred to SW, with levels being significantly lower in the rAQP3-injected group. Hence, cortisol appears to be a stress hormone and plasma Na(+) and Cl(-) levels significantly increased when the fish were transferred to SW, with levels being significantly lower in the rAQP3-treated group. These results indicate that rAQP3 modulates the HPI axis and ion transportation in rainbow trout.
authors.affiliation: Division of Marine BioScience, Korea Maritime University, Busan 606-791, Republic of Korea.
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Division of Marine BioScience, Korea Maritime University, Busan 606-791, Republic of Korea.
authors.forename: Na Na
authors.initials: NN
authors.lastname: Kim
authors.affiliation: Division of Marine BioScience, Korea Maritime University, Busan 606-791, Republic of Korea. Electronic address: choic@kmou.ac.kr.
authors.forename: Cheol Young
authors.initials: CY
authors.lastname: Choi
mesh_terms: D000064:Acclimatization; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000235:genetics; D000818:Animals; D051400:Aquaporin 3 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D002712:Chlorides / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000235:genetics; D005618:Fresh Water; D005786:Gene Expression Regulation / Q000187:drug effects; D006854:Hydrocortisone / Q000097:blood; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D007668:Kidney / Q000502:physiology; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000502:physiology*; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology; D011188:Potassium / Q000097:blood; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D054712:Salinity; D012964:Sodium / Q000097:blood
chemical_list: D001786:Blood Glucose; D002712:Chlorides; D011994:Recombinant Proteins; D051400:Aquaporin 3; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D012964:Sodium; D011188:Potassium; D006854:Hydrocortisone
keywords: HPI axis; Parr; Rainbow trout; Recombinant AQP3; Salinity; Smolt