m/z peaks that differed among the four groups, 17 were significantly different (P-lt;-.05). Five peaks (m/z: 2793.37, 2924.86, 1979.90, 3492.49, 3880.24) showed significant differences in expression after exposure to terrified-sound stress and returned to control levels after stress release. These were sequence identified as peptide regions of dimethylaniline monooxygenase, myosin-9, uncharacterized protein in Rattus norvegicus, apolipoprotein C-I, and plasma serine protease inhibitor (Serpina 5). Our study provides the first evidence of significant changes in serum proteomic profiles in mice exposed to terrified-sound stress, which suggests that protein expression profiles are affected by the stress. Normal expression levels were restored after stress release, suggesting the activation of self-adjustment mechanisms for the recovery of protein expression levels altered by this stress. Keywords Terrified-sound-induced stress Serum proteomic profiling Stress release Protein expression" />