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Thyroid hormone effect on activity levels and tissue mitochondrial biogenesis and function in young and old rats
Author(s) -
Klaus Katherine A,
Walrand Stephane,
Morse Dawn,
Schimke Jill M,
Short Kevin R,
Novak Colleen,
Levine James A,
Nair K. Sreekumaran
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1163.22
Subject(s) - medicine , endocrinology , soleus muscle , triiodothyronine , mitochondrial biogenesis , chemistry , citrate synthase , hormone , biology , skeletal muscle , mitochondrion , enzyme , biochemistry
Triiodothyronine (T3) has a major impact on the regulation of energetics and mitochondrial (mt) function. We determined whether chronic T3 administration alters the age‐related decline in mt function. Ten young (Y, 8 mo) and ten old (O, 27 mo) F344/BN rats were randomized to receive T3 (200 mg/d) or placebo for 14d via subcutaneous osmotic pump. Because OT3 rats decreased food consumption by 39%, we added ten pair fed rats (OPF). T3 treatment caused a significant weight loss (Y, −11.97%; O, −17.49%), while energy expenditure increased in both Y (50.86%) and O (54.40%), but decreased in PF (17.55%). Fat and muscle loss were similar in Y and O in response to T3 (fat, −52.53%(Y) vs −51.69% (O); muscle, −21.50% (Y) vs −21.03% (O) in soleus and −16.70% (Y) vs −17.35% (O) in plantaris), whereas these changes were minor with OPF (fat, −10.4%; soleus −1.69% ; plantaris 7.69%). While mt ATP production and citrate synthase activity in heart and soleus muscle were lower in O, these measures increased equally in Y and O in response to T3. In the soleus, mt DNA abundance increased in Y (54.39%) and O (23.36%) and UCP3 expression increased 10‐fold in both age groups. Gene transcripts levels of PGC1α, COX3&4 and NADH4, UCP2& 3 increased in soleus of T3 rats. In conclusion, T3 similarly increased energy expenditure, weight loss and mt biogenesis in both Y and O rats, despite differences in food intake. NIH grant PO1 AG09531 and Mayo Foundation