In the current study, plasma cytokines, including interleukin (IL) 1, IL-2, IL-6, IL-10, IL-12, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) and catecholamines (adrenaline and noradrenaline) were evaluated during 4 h restraint and recovery phase in 60 male pigs. Blood samples were collected from three groups of pigs representing different RYR1 genotypes, namely NN homozygotes (wild-type), Nn heterozygous and nn homozygous (mutant). The 4 h restraint evoked an increase in plasma cytokine concentrations in each of the RYR1 genotype groups. During the restraint, the greatest concentrations of plasma IL-6, IL-10, IL-12 and TNF-alpha in nn homozygous pigs and IFN-gamma in NN homozygous were observed. Interleukin 1, IL-2, IL-10, and TNF-alpha measures were positively intercorrelated in each of the three RYR1 genotype group. A positive correlation was seen between all measured cytokines (with the exception of IL-6) and plasma catecholamine concentrations in Nn heterozygous and nn homozygous pigs. The results suggest that of the cytokine parameters evaluated, IL-6, IL-10, IL-12 and TNF-alpha of the nn homozygous group seem to show a stronger stress-related response as compared with those of the other two (NN and Nn) groups. (C) 2013 Elsevier B.V. All rights reserved.