Objective:To explore the expression changes of N6-methyladenosine (m6A)-related proteins in the hippocampus of mice with post traumatic stress disorder (PTSD)-like behavior and the therapeutic effects of sertraline hydrochloride.Methods:Male C57BL/6J mice aged 4-6 weeks were selected to establish a PTSD model using a single prolonged stress and foot shock stimulation. A total of 24 mice were randomly divided into the control group, model group, and sertraline group using a random number table, with 8 mice in each group. Mice in the sertraline group were intraperitoneally injected with sertraline hydrochloride (15 mg/kg, once daily) 24 h after PTSD modelling, continuing for 14 days. Mice in the control group and model group were injected with an equal volume of 0.9% NaCl solution (once daily, for 14 days). The anxiety, despair, and learning and memory functions of the mice were assessed using the open field test, Y-maze test, and forced swimming test. Western blot was performed to measure the protein expression levels of methyltransferase-like protein 3 (METTL3), fat mass and obesity-associated gene (FTO), ALKB homolog 5 (ALKBH5), Wilms tumour 1 associating protein (WTAP), and methyltransferase-like protein 14 (METTL14) in the hippocampus. Immunofluorescence was used to detect the expression levels of METTL3, FTO, and ALKBH5 in the hippocampus. Statistical analysis was performed using SPSS 26.0 and GraphPad Prism 9.0.Comparisons between two groups were conducted using independent samples t-test, while comparisons among three groups were performed using one-way analysis of variance (ANOVA) or Kruskal-Wallis H test, followed by pairwise comparisons using LSD test. Results:(1) Behavioral results showed that the total distance travelled in the central area ( F=9.231, P<0.05) and the time spent in the central area ( H=8.045, P<0.05) showed statistically significant differences among the control, model, and sertraline groups. Mice in the control and sertraline groups travelled a greater distance((332.68±121.17)cm, (248.56±40.21)cm) and spent more time(24.98(23.08, 26.71)s, 22.52(18.86, 26.20)s) in the central area than those in the model group((131.66±84.90)cm, 9.14(6.56, 18.53)s) (all P<0.05). In the forced swimming test, the number of resting episodes ( F=16.882, P<0.05) and the duration of rest ( H=12.285, P<0.05) differed significantly among the three groups. Mice in the control group ((19.14±8.30) counts, 30.21 (18.98, 52.62) s) and the sertraline group ((17.63±8.14) counts, 25.90 (16.78, 37.56) s) had fewer resting episodes and shorter resting durations compared to those in the model group ((37.75±6.47) counts, 83.37 (64.62, 124.42) s) (all P<0.05). The percentage of alternations in the Y-maze experiment showed significant statistical differences among the three groups( F=6.844, P<0.05). Mice in the control group ((51.33±11.49)%) and the sertraline group ((48.24±3.10)%) exhibited a higher percentage of alternations than that in the model group ((36.70±8.15)%) ( P<0.05). (2) Western blot results showed that the protein expression levels of METTL3, FTO, and ALKBH5 in the hippocampal tissue of the three groups showed significant differences ( F=10.263, 9.010, 6.950, all P<0.05). The METTL3 and FTO protein expression levels in the hippocampus in the control group (0.85±0.07, 0.86±0.04) and the sertraline group (0.93±0.06, 0.95±0.13) were higher than those in the model group (0.74±0.02, 0.68±0.04) (all P<0.05). However, the ALKBH5 protein expression levels in the control group (0.93±0.08) and the sertraline group (0.87±0.13) were lower than that in the model group (1.13±0.04) (both P<0.05). (3) Immunofluorescence results showed that the expression levels of METTL3, FTO, and ALKBH5 proteins in the hippocampal tissue of the three groups showed significant statistical differences ( F=37.912, 62.659, 54.417, all P<0.05). The expression levels of METTL3 and FTO in the hippocampus in the control group (14.03±0.32, 13.85±0.28) and the sertraline group (17.94±0.29, 10.52±0.66) were higher than those in the model group (11.67±1.48, 8.70±0.68) (all P<0.05). The expression levels of ALKBH5 in the control group (12.94±0.38) and the sertraline group (13.30±0.93) were lower than that in the model group (19.24±1.03) (both P<0.05). Conclusion:The expression of m6A-related proteins in the hippocampus of PTSD-like mice is altered. Sertraline treatment can significantly regulate the expression of these proteins and improve anxiety, despair, and learning and memory impairments in the PTSD-like mice.

Objective:To explore the expression changes of N6-methyladenosine (m6A)-related proteins in the hippocampus of mice with post traumatic stress disorder (PTSD)-like behavior and the therapeutic effects of sertraline hydrochloride.Methods:Male C57BL/6J mice aged 4-6 weeks were selected to establish a PTSD model using a single prolonged stress and foot shock stimulation. A total of 24 mice were randomly divided into the control group, model group, and sertraline group using a random number table, with 8 mice in each group. Mice in the sertraline group were intraperitoneally injected with sertraline hydrochloride (15 mg/kg, once daily) 24 h after PTSD modelling, continuing for 14 days. Mice in the control group and model group were injected with an equal volume of 0.9% NaCl solution (once daily, for 14 days). The anxiety, despair, and learning and memory functions of the mice were assessed using the open field test, Y-maze test, and forced swimming test. Western blot was performed to measure the protein expression levels of methyltransferase-like protein 3 (METTL3), fat mass and obesity-associated gene (FTO), ALKB homolog 5 (ALKBH5), Wilms tumour 1 associating protein (WTAP), and methyltransferase-like protein 14 (METTL14) in the hippocampus. Immunofluorescence was used to detect the expression levels of METTL3, FTO, and ALKBH5 in the hippocampus. Statistical analysis was performed using SPSS 26.0 and GraphPad Prism 9.0.Comparisons between two groups were conducted using independent samples t-test, while comparisons among three groups were performed using one-way analysis of variance (ANOVA) or Kruskal-Wallis H test, followed by pairwise comparisons using LSD test. Results:(1) Behavioral results showed that the total distance travelled in the central area ( F=9.231, P<0.05) and the time spent in the central area ( H=8.045, P<0.05) showed statistically significant differences among the control, model, and sertraline groups. Mice in the control and sertraline groups travelled a greater distance((332.68±121.17)cm, (248.56±40.21)cm) and spent more time(24.98(23.08, 26.71)s, 22.52(18.86, 26.20)s) in the central area than those in the model group((131.66±84.90)cm, 9.14(6.56, 18.53)s) (all P<0.05). In the forced swimming test, the number of resting episodes ( F=16.882, P<0.05) and the duration of rest ( H=12.285, P<0.05) differed significantly among the three groups. Mice in the control group ((19.14±8.30) counts, 30.21 (18.98, 52.62) s) and the sertraline group ((17.63±8.14) counts, 25.90 (16.78, 37.56) s) had fewer resting episodes and shorter resting durations compared to those in the model group ((37.75±6.47) counts, 83.37 (64.62, 124.42) s) (all P<0.05). The percentage of alternations in the Y-maze experiment showed significant statistical differences among the three groups( F=6.844, P<0.05). Mice in the control group ((51.33±11.49)%) and the sertraline group ((48.24±3.10)%) exhibited a higher percentage of alternations than that in the model group ((36.70±8.15)%) ( P<0.05). (2) Western blot results showed that the protein expression levels of METTL3, FTO, and ALKBH5 in the hippocampal tissue of the three groups showed significant differences ( F=10.263, 9.010, 6.950, all P<0.05). The METTL3 and FTO protein expression levels in the hippocampus in the control group (0.85±0.07, 0.86±0.04) and the sertraline group (0.93±0.06, 0.95±0.13) were higher than those in the model group (0.74±0.02, 0.68±0.04) (all P<0.05). However, the ALKBH5 protein expression levels in the control group (0.93±0.08) and the sertraline group (0.87±0.13) were lower than that in the model group (1.13±0.04) (both P<0.05). (3) Immunofluorescence results showed that the expression levels of METTL3, FTO, and ALKBH5 proteins in the hippocampal tissue of the three groups showed significant statistical differences ( F=37.912, 62.659, 54.417, all P<0.05). The expression levels of METTL3 and FTO in the hippocampus in the control group (14.03±0.32, 13.85±0.28) and the sertraline group (17.94±0.29, 10.52±0.66) were higher than those in the model group (11.67±1.48, 8.70±0.68) (all P<0.05). The expression levels of ALKBH5 in the control group (12.94±0.38) and the sertraline group (13.30±0.93) were lower than that in the model group (19.24±1.03) (both P<0.05). Conclusion:The expression of m6A-related proteins in the hippocampus of PTSD-like mice is altered. Sertraline treatment can significantly regulate the expression of these proteins and improve anxiety, despair, and learning and memory impairments in the PTSD-like mice.