Rutin via Increase in the CA3 Diameter of the Hippocampus Exerted Antidepressant-Like Effect in Mouse Model of Maternal Separation Stress: Possible Involvement of NMDA Receptors

Abstract

Methods: Mouse neonates were exposed to MS paradigm 3 hours daily from postnatal days (PND) 2 to 14. The control and MS mice were divided separately into 16 groups (n = 8) (8 groups for each set) including mice that received normal saline, mice that received rutin at doses of 10, 50, and 100 mg/kg, mice that received NMDA at a dose of 150 mg/kg, mice that received ketamine (NMDA antagonist) at a dose of 0.25 mg/kg, mice that received NMDA antagonist plus a subeffective dose of rutin, and mice that received NMDA plus an effective dose of rutin. Forced swimming test (FST) was performed. Afterwards, the hippocampus was evaluated in cases of histopathological changes as well as expression of NR2A and NR2B genes.

Results: Rutin significantly reduced immobility time in the FST. The expression of NR2A and NR2B subunits of NMDA receptor in MS mice was significantly higher than that in the control group. Rutin significantly decreased the expression of NR2B and NR2A subunits in the hippocampus. The CA3 diameter and percentage of dark neurons in the hippocampus of MS mice significantly decreased and increased, respectively, which partially reversed following rutin administration.

Conclusion: Rutin, partially, through a neuroprotective effect on the hippocampus exerted antidepressant-like effect. We concluded that NMDA receptors, at least in part, mediated the beneficial effect of rutin.

Figure 1

Comparison of immobilization duration in forced swimming test in experimental groups. Data are expressed as mean ± SEM (ANOVA and Tukey post hoc test). ^###P < 0.001 compared with the control group (normal), and ∗P < 0.05 and ∗∗∗P < 0.001 in comparison with the MS group. ^$P < 0.05 compared with the MS group which received rutin at the dose of 100 mg/kg. MS: maternal separation.

Figure 2

Comparison of the expression of NR2A and NR2B genes in the hippocampus. Data are expressed as mean ± SEM (ANOVA and Tukey post hoc test). ∗P < 0.05, ∗∗P < 0.01, and ∗∗∗P < 0.001 in comparison with the control group. ^#P < 0.05, ^##P < 0.01, and ^###P < 0.001 in comparison with the MS group. ^$P < 0.05 in comparison with the MS group which received rutin at a dose of 10 mg/kg. ^@P < 0.05 in comparison with the MS group which received rutin at a dose of 100 mg/kg. MS: maternal separation.

Figure 3

Comparison of hippocampal CA3 region diameter in experimental groups. Data are expressed as mean ± SEM (ANOVA and Tukey post hoc test). ∗P < 0.05 and ∗∗P < 0.01 in comparison with the control group. ^#P < 0.05 and ^##P < 0.01 in comparison with the MS group. ^@P < 0.05 in comparison with the MS group which received rutin at the dose of 100 mg/kg. MS: maternal separation.

Figure 4

Representative features from the diameter of the CA3 region of the hippocampus pyramidal area. (a) Control, (b) MS, (c) rutin 10 (control), (d) rutin 10 (MS), (e) rutin 50 (control), (f) rutin 50 (MS), (g) rutin 100 (control), (h) rutin 100 (MS), (i) NMDA 150 (control), (j) ketamine 0.25 (control), (k) NMDA 150 (MS), (l) ketamine 0.25 (MS), (m) rutin 10+ketamine (MS), and (n) rutin 100+NMDA (MS). H&E staining (scale bar = 25 micrometer).

Figure 5

Percentage of dark hippocampal neurons in experimental groups. Data are expressed as mean ± SEM (ANOVA and Tukey post hoc test). ∗∗P < 0.01 in comparison with the control group. ^##P < 0.01 in comparison with the MS group. MS: maternal separation.

Figure 6

Representative features from dark neurons in the CA3 region of the hippocampus pyramidal area. (a) Control, (b) MS, (c) rutin 10 (control), (d) rutin 10 (MS), (e) rutin 50 (control), (f) Rutin 50 (MS), (g) rutin 100 (control), (h) rutin 100 (MS), (i) NMDA 150 (control), (j) ketamine 0.25 (control), (k) NMDA 150 (MS), (l) ketamine 0.25 (MS), (m) rutin 10+ketamine (MS), and (n) rutin 100+NMDA (MS). H&E staining (scale bar = 25 micrometer).