Analysis of left ventricular function of the mouse heart during experimentally induced hyperthyroidism and recovery.
Many of the clinical manifestations of hyperthyroidism are due to the ability of thyroid hormones to alter myocardial contractility and cardiovascular hemodynamics, leading to cardiovascular impairment. In contrast, recent studies highlight also the potential beneficial effects of thyroid hormone administration for clinical or preclinical treatment of different diseases such as atherosclerosis, obesity and diabetes or as a new therapeutic approach in demyelinating disorders. In these contexts and in the view of developing thyroid hormone-based therapeutic strategies, it is, however, important to analyze undesirable secondary effects on the heart. Animal models of experimentally induced hyperthyroidism therefore represent important tools for investigating and monitoring changes of cardiac function. In our present study we use high-field cardiac MRI to monitor and follow-up longitudinally the effects of prolonged thyroid hormone (triiodothyronine) administration focusing on murine left ventricular function. Using a 9.4 T small horizontal bore animal scanner, cinematographic MRI was used to analyze changes in ejection fraction, wall thickening, systolic index and fractional shortening. Cardiac MRI investigations were performed after sustained cycles of triiodothyronine administration and treatment arrest in adolescent (8 week old) and adult (24 week old) female C57Bl/6 N mice. Triiodothyronine supplementation of 3 weeks led to an impairment of cardiac performance with a decline in ejection fraction, wall thickening, systolic index and fractional shortening in both age groups but with a higher extent in the group of adolescent mice. However, after a hormonal treatment cessation of 3 weeks, only young mice are able to partly restore cardiac performance in contrast to adult mice lacking this recovery potential and therefore indicating a presence of chronically developed heart pathology.
Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany.
Neele Saskia
NS
Hübner
Annette
A
Merkle
Bernd
B
Jung
Dominik
D
von Elverfeldt
Laura-Adela
LA
Harsan
D000818:Animals; D005260:Female; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D006980:Hyperthyroidism / Q000139:chemically induced* / Q000503:physiopathology*; D008810:Mice, Inbred C57BL; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013599:Systole / Q000187:drug effects; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects
D014284:Triiodothyronine
cardiovascular impairments; mouse cardiac MRI, age effects; thyroid hormone administration