Peripheral and cerebral inflammation induced by repeated anesthesia and surgery do not cause impairment of learning and memory in middle‑aged mice

Abstract

Postoperative cognitive dysfunction is a postoperative complication of the central nervous system that reduces quality of life and increases mortality in perioperative patients, especially among elderly patients. Many studies have shown that the incidence of postoperative cognitive impairment in adults induced by one‑time anesthesia and surgery is very low, while multiple experiences of anesthesia and surgery can induce cognitive impairment in the developing brain. However, the effect of multiple experiences of anesthesia and surgery on cognitive function over a short period in middle‑aged mice, i.e., 6 to 8 months old, remains unclear. In this study, we explored whether the cognitive function of mice aged 6–8 months is impaired after multiple operations. Middle‑aged mice (6 to 8 months old) healthy male C57BL/6 mice underwent exploratory laparotomy under isoflurane anesthesia. Morris water maze testing was performed after the operations. Blood and brain samples were collected at 6 h, 24 h, and 48 h after the operations. Serum IL‑6, IL‑1, and S‑100β concentrations were detected by ELISA. The expressions of ChAT, AChE, and Aβ in the hippocampus were measured by western blot. Up‑regulation of Iba1 and GFAP, respectively, indicated activation of microglia and astrocytes in the hippocampus. Expression of Iba1 and GFAP was examined by immunofluorescence. The present results revealed that serum IL‑6, IL‑1β, and S‑100β concentrations were enhanced after multiple instances of anesthesia and surgery, and microglia and astrocytes in the hippocampus were activated. However, learning and memory were not impaired in the middle‑aged mice by multiple experiences of anesthesia and surgery. There were no changes in ChAT, AChE, and Aβ in the hippocampus after multiple experiences of anesthesia/surgery. Taken together, we suggest that although multiple anesthesia/surgery procedures can induce peripheral inflammation, neuroinflammation, and transient cerebral injury, it is insufficient to impair learning and memory in middle‑aged mice.