Elderly patients may experience impairments in cognition or mood following surgery. To study the development and underlying mechanisms of these postoperative behavioral changes, young (3 months) and aged (18-20 months) male rats were subjected to abdominal surgery followed by behavioral testing during a period of 6 weeks. Microglia activation (IBA-1) and neurogenesis (DCX) were immunohistochemically determined. In separate experiments, the effects of anesthesia and the cytokine response (IL-6) following surgery were evaluated. Increased age was associated with changes in affective behavior, decreased cognitive flexibility and increased microglia activation as well as increased weight loss and plasma IL-6 following surgery. No effects of surgery on cognition were observed at either age. However, aged rats displayed long-term changes in affective behavior and had increased microgliosis in the CA1 hippocampal region following surgery. Microglia activation following surgery was positively correlated to parameters of behavior and spatial learning. These findings support the hypothesis that elderly patients have an increased behavioral and (neuro)inflammatory response to surgery and these factors may be related.
Keywords: AUC; Aging; BLA; BSA; CA 3; CA1; CFC; Cognition; DCX; DG; DGib; EDTA; EP; IBA-1; IL-6; Inflammation; MWM; MWM test; MWM-T; Microglia; Mood; Morris water maze; NRS; PFC; POCD; PVP; Postoperative cognitive dysfunction; SMA; Surgery; TX; Triton-X; Y-maze reversal task; Y-maze spatial reference task; YM; YM-R; YM-S; area under the curve; basolateral amygdala; bovine serum albumin; contextual fear conditioning test; cornu ammonis region 1; cornu ammonis region 3; dentate gyrus; dentate gyrus inner blade; doublecortin-X; elevated plus maze; ethylenediaminetetraacetic acid; interleukin 6; ionized calcium binding adaptor molecule 1; normal rabbit serum; polyvinylpyrrolidone; postoperative cognitive dysfunction; prefrontal cortex; sensory motor area; spontaneous alternation in the Y-maze.