BDNF and Cognitive impairment: Further, the mRNA levels of BDNF and NG were up‐regulated while VILIP‐1 was down‐regulated after exogenous microglial miR‐124‐3p administration compared with Scramble administration in postoperative pain mice (Figure 6E), suggesting that exogenous microglial miR‐124‐3p increased neuroprotective factors, which could be relevant to cognitive impairment induced by postoperative pain in elderly mice.