No mice in the sham + vehicle group died 14 days after surgery, while the 14-day survival rate after CLP was only 45% (Fig.
1B). The survival rate slightly increased after ICM administration, but there was no significant difference between the two groups (Fig.
1B). Postoperative body weight significantly decreased after CLP, but there was no significant difference between the CLP and CLP + ICM groups (Fig.
1C). To assess locomotor activity and cognitive function, we performed OFT, Y maze, and NOR on days 14–18 after surgery. In the OFT, there was no significant difference in total distance traveled [Fig.
1D; interaction: CLP × ICM, F (1, 36) = 0.01335,
P = 0.9087; CLP: F (1, 36) = 1.206,
P = 0.8753; ICM: F (1, 36) = 2.537,
P = 0.9391], distance traveled in the center [Fig.
1E; interaction: CLP × ICM, F (1, 36) = 1.246,
P = 0.2717; CLP: F (1, 36) = 0.04634,
P = 0.9996; ICM: F (1, 36) = 1.584,
P = 0.7558], and time spent in the center [Fig.
1F; interaction: CLP × ICM, F (1, 36) = 0.3539,
P = 0.5556; CLP: F (1, 36) = 0.5084,
P = 0.8833; ICM: F (1, 36) = 0.1762,
P = 0.7657] among the four groups (Fig.
1D, E). In the NOR test, the mice in the CLP + vehicle group spent less time with novel objects than those in the sham + vehicle group; this effect was reversed by ICM treatment [Fig.
1G; interaction: CLP × ICM, F (1, 33) = 8.644,
P = 0.0060; CLP: F (1, 33) = 8.767,
P < 0. 05; ICM: F (1, 33) = 1.981,
P < 0.001]. In the Y maze test, compared with the sham + vehicle group, the CLP + vehicle group showed a significant decrease in spontaneous alternation, and this effect was reversed by ICM treatment [Fig.
1H; interaction: CLP × ICM, F (1, 38) = 10.61,
P = 0.0024; CLP: F (1, 38) = 9.633,
P < 0.0001; ICM: F (1, 38) = 16.25,
P < 0.001]. These results indicate that inhibiting HMGB1 rescues cognitive impairment in septic mice.