test Browse by Author Names Browse by Titles of Works Browse by Subjects of Works Browse by Issue Dates of Works

Advanced Search
& Collections
Issue Date   
Sign on to:   
Receive email
My Account
authorized users
Edit Profile   
About T-Space   

T-Space at The University of Toronto Libraries >
University of Toronto at Scarborough >
Biological Sciences >
Biology >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/682

Title: Changes in intestinal and hepatic thyroid hormone deiodination during spontaneous metamorphosis of the sea lamprey, Petromyzon marinus
Authors: Eales, Geoffrey
McLeese, Jennifer
Holmes, John
Youson, John
Keywords: Thyroid hormones; Potassium perchlorate; Lipid metabolism lipolysis; Lipogenesis; Sea lamprey; Petromyzon marinus; Metamorphosis
Issue Date: 2000
Publisher: Wiley-Liss, Inc.
Citation: J. Exp. Zool. 286: 305-312, 2000.
Abstract: This study examines the role of thyroid hormones (TH) (thyroxine and triiodothyronine) in regulating lipid metabolism of landlocked larval sea lampreys, Petromyzon marinus. Larvae were treated with either thyroxine (0.5 or 1 mg l−1 water) or triiodothyronine (0.25 or 1 mg l−1 water) in the presence or absence of the goitrogen, potassium perchlorate (KClO4) (0.05% w/v), for 4, 8, and 16 weeks. Treatment with KClO4 alone, which induced metamorphosis after 8 weeks and lowered plasma TH levels, reduced hepatic and renal total lipid content after 8 weeks of treatment. KClO4-induced lipid depletion after the 8-week treatment was supported by an increased rate of hepatic lipolysis, as indicated by increased triacylglycerol lipase activity. Furthermore, reduced lipogenesis in the liver was indicated by decreased hepatic acetyl-CoA carboxylase and diacylglycerol acyltransferase (DGAT) activities, and by decreased renal DGAT activity following 8 weeks of KClO4 treatment. Treatment of larvae for 4 weeks with TH alone resulted in either no change or a slight increase of lipid in the liver and kidney. TH treatments in combination with KClO4 failed to induce metamorphosis and, after up to 8 weeks, several TH treatments blocked changes in lipid content and enzyme activity associated with KClO4-induced metamorphosis. These experimental results suggest that TH deficiency during metamorphosis may promote lipid catabolism, while the presence of TH tends to protect/promote lipid reserves, perhaps favoring the larval condition. The actions of TH and KClO4 on metamorphosis-associated lipid metabolism in sea lampreys may be direct, permissive, and/or indirect via other factors.
URI: http://hdl.handle.net/1807/682
Appears in Collections:Biology

Files in This Item:

File Description SizeFormat
Changes_in_intestinal_and_hepatic_thyroid_hormone.pdf127.38 kBAdobe PDF

Items in T-Space are protected by copyright, with all rights reserved, unless otherwise indicated.