Objective:To investigate the role of cyclophilin D (CypD) in parvalbumin (PV) interneurons in long-term cognitive dysfunction induced by multiple sevoflurane anesthesia in neonatal mice.Methods:Thirty-two specific pathogen-free healthy PV Cre mice and 32 specific pathogen-free healthy Ppif F/F-PV Cre mice, aged 6 days, were selected and divided into 4 groups ( n=16 each) using a random number table method: control group of PV Cre mice (Con group), sevoflurane exposure group of PV Cre mice (Sevo group), control group of Ppif F/F-PV Cre mice (CKO-Con group), and sevoflurane exposure group of Ppif F/F-PV Cre mice (CKO-Sevo group). Sevo group and CKO-Sevo group were exposed to 3% sevoflurane for 2 h from the 6th day to the 8th day, while Con group and CKO-Con group inhaled a mixture of 30% O 2 and 70% air for 2 h at the corresponding time points. On the 42th day of age, the learning and memory abilities of mice in all four groups were evaluated using the novel object recognition test and Morris water maze test. After conducting behavioral experiments, the mice were sacrificed, and hippocampal tissues were collected to determine the expression of PV, CypD, and postsynaptic density protein-95 (PSD95) in the hippocampus (by Western blot) and to measure the mitochondrial membrane potential (MMP) and activity of reactive oxygen species (ROS). Results:Compared to Con group, the novel object recognition index was significantly decreased, the escape latency was prolonged, the time of staying at the original platform quadrant was shortened, the number of crossing the original platform was reduced, the MMP was decreased, the activity of ROS was increased, the expression of CypD was up-regulated, and the expression of PV and PSD95 was down-regulated in Sevo group ( P<0.05). Compared to Sevo group, the novel object recognition index was significantly increased, the escape latency was shortened, the time of staying at the original platform quadrant was prolonged, the number of crossing the original platform was increased, MMP was increased, the activity of ROS was decreased, the expression of CypD was down-regulated, and the expression of PV and PSD95 was up-regulated in CKO-Sevo group ( P<0.05). There were no statistically significant differences in the novel object recognition index, escape latency, residence time in the original platform quadrant, the number of crossing the original platform position, MMP, ROS activity and expression of PV and PSD95 among Con group, CKO-Con group and CKO-Sevo group ( P>0.05). Conclusions:Up-regulation of CypD expression in PV interneurons is involved in the long-term cognitive dysfunction in neonatal mice subjected to multiple sevoflurane anesthesia.