THE ENDOCRINE CONTROL OF NA+,K+-ATPASE α-SUBUNIT EXPRESSION AND ENZYME ACTIVITY IN THE GILL OF ATLANTIC SALMON: A COMPARISON OF A NATURAL HYPOTHYROID MODEL WITH THYROID HORMONE TREATMENT

• Main Author: Lars O. E. Ebbesson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.484.7027; http://www-heb.pac.dfo-mpo.gc.ca/congress/2002/IonReg/ebbesson.pdf

Thyroid hormones have been implicated in many of the physiological changes that occur during salmon smoltification, however the role of thyroid hormones in osmoregulation has been suggested to be a modulatory one, interacting with growth hormone and cortisol to regulate the osmoregulatory machinery in the gill. Here we present data from two experiments seeking to elucidate the specific localization and functional actions by thyroid hormones during smoltification in the Atlantic salmon (Salmo salar L.). The first experiment compared endocrine and branchial smoltification-related changes in an anadromous strain and a landlocked strain of Atlantic salmon. Previously, we have reported the osmoregulatory differences between these landlocked and anadromous strains and demonstrated a 3-fold difference in 89 Na+,K+-ATPase activity and the inability for the landlocked strain to survive long term in seawater (Nilsen et al., in press). We show now that in the landlocked strain circulating thyroxine (T4) and growth hormone (GH) peak