Horm Metab Res 2008; 40(1): 1-7
DOI: 10.1055/s-2007-1004554
Original Basic

© Georg Thieme Verlag KG Stuttgart · New York

Thyroid Function and Body Weight Programming by Neonatal Hyperthyroidism in Rats - The Role of Leptin and Deiodinase Activities

E. G. Moura 1 , R. S. Santos 1 , P. C. Lisboa 1 , S. B. Alves 1 , I. T. Bonomo 1 , A. T. S. Fagundes 1 , E. Oliveira 1 , M. C. F. Passos 2
  • 1Department of Physiological Sciences, Biology Institute Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
  • 2Department of Applied Nutrition, Nutrition Institute, State University of Rio de Janeiro, Rio de Janeiro, Brazil
Further Information

Publication History

received 21.03.2007

accepted 05.06.2007

Publication Date:
15 January 2008 (online)

Abstract

Several authors have shown that secondary hypothyroidism was programed by neonatal thyroxine (T4) treatment. However, the associated changes of body weight (BW) were less studied, especially those related to the body fat proportion. Here, we have evaluated the effect of neonatal thyroxine treatment on BW, fat proportion, serum leptin, and thyroid function of 60-day-old rats. Wistar rats were treated with thyroxine (50 μg/100 g BW, ip) (T) or saline (S), during the first 10 days of life. BW, nose-rump length (NRL), and food consumption were monitored for 60 days, when the animals were sacrificed. Thyroid function was evaluated by thyroid radioiodine uptake (RAIU), serum T3, T4, TSH, and liver mitochondrial alpha-glycerophosphate dehydrogenase (mGPD) and type 1 and 2 deiodinases (D1 and D2) activities, which are thyroid hormone-dependent enzymes. T animals showed lower food intake, BW and NRL, but higher total fat mass (+33%) and serum leptin (+46%). They also showed lower serum T3 (-23%), T4 (-32%), TSH (-36%), RAIU (-29%) and mGPD activity (-22%). Hypothalamic and pituitary D2 activities were higher (+24% and 1.4 fold, respectively), while brown adipose tissue (BAT) D2 and skeletal muscle D1 activities were lower (-30% and -62%, respectively). Thus, neonatal hyperthyroidism programs for a higher fat proportion and hyperleptinemia, which can explain the lower food intake. The TH-dependent enzymes activities changed accordingly, except for the decrease in BAT D2, which may be due the role played by the hyperleptinemia. Finally, the decrease in peripheral deiodination may contribute to a lower me-tabolic rate that may increase the adiposity.

References

Correspondence

Dr. E.G. Moura

Departamento de Ciências Fisiológicas - 5o andar

Instituto de Biologia

Universidade do Estado do Rio de Janeiro

Av. 28 de setembro

87- Rio de Janeiro

20550-030 Brazil

Phone: +55/21/2587 64 34

Fax: +55/21/2587 61 29

Email: egberto@pq.cnpq.br