Experimental schedule. Aged rats were divided into four groups: control, surgery, surgery+ TSA and TSA. Rats in the surgery + TSA and TSA groups were intraperitoneally administered 1 mg/kg TSA 30 min before surgery or sham under isoflurane anesthesia. Protocol 1: After the surgery, blood samples (0.5 ml) were immediately collected for arterial blood gas and blood glucose analysis. Protocol 2: Spatial learning and memory were then tested using the Morris water maze (MWM) task on day 2 postsurgery. Protocol 3: Markers for microglial activation and some of inflammatory cytokine in the hippocampus were determined at 6, 24 and 72 h after surgery, respectively. At the peak of neuroflammation we have observed, at 6 h postsurgery, the protein profile alterations in the hippocampus were assessed using iTRAQ. Then, bioinformatics analysis was performed. Surgery: abdominal exploratory surgery; TSA: Trichostatin A.