©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 13 (3): 7294-7303 (2014) Acute heat stress and dietary methionine effects on IGF-I, GHR, and UCP mRNA expression in liver and muscle of quails A.P. Del Vesco 1 , E. Gasparino 1 , V. Zancanela 1 , D.O. Grieser 1 , S.E.F. Guimarães 2 , C.S. Nascimento 2 , D.M. Voltolini 1 , J. Constantin 3 and F.S. Gasparin 3 1 Departamento de Zootecnia, Universidade Estadual de Maringá, Maringá, PR, Brasil 2 Departamento de Zootecnia, Universidade Federal de Viçosa, Viçosa, MG, Brasil 3 Departamento de Bioquímica, Universidade Estadual de Maringá, Maringá, PR, Brasil Corresponding author: A.P. Del Vesco E-mail: egasparino@uem.br Genet. Mol. Res. 13 (3): 7294-7303 (2014) Received March 28, 2013 Accepted August 20, 2013 Published February 13, 2014 DOI http://dx.doi.org/10.4238/2014.February.13.12 ABSTRACT. This study evaluated the expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), and uncoupling protein (UCP) mRNA in muscle and liver of quails that were in thermal comfort or exposed to heat stress and that were fed diets with or without methionine supplementation. Meat quails were fed a diet that either met the nutritional demands for methionine (MS) or did not meet this demand (methionine- defcient diet, MD). The animals were either kept at a thermal comfort temperature (25°C) or exposed to heat stress (38°C for 24 h starting on the 6th day). RNA was extracted from liver and breast muscle, and cDNA was synthesized and amplifed using quantitative reverse transcription- polymerase chain reaction. Animals that were fed the MS diet and remained at the thermal comfort temperature exhibited increased IGF-I mRNA