| ObjectiveTo establish a new postpartum depression (PPD) animal model which was induced by pre-pregnancy stress, assess abnormal maternal depressive-like behavior. To detect the expression of Disrupted in schizophrenia 1 (DISCI) in the hippocampus on the PPD mice model, and explore the effect of PS on the expression of DISC1-Akt-mTOR signaling pathway protein in the hippocampus and effects on neurogenesis in dentate gyrus (DG) cells, reveal the molecμlar mechanism of the depressive-like behavior on the PPD model. To observe the rapid antidepressant effects of acute Yueju-ganmaidazao Decoction (YG) on depressive-like behavior and protein expression of NR1, Akt, mTOR, P70S6K,4E-BP1, GluRl, and further explore the mechanism of rapid antidepressant effects of YG on PPD by regμlating DISCI signaling pathway, which is provide scientific theoretical basis and experimental evidence for prevention, treatment, research and drugs’development of PPD.Methods1. Female Balb/c mice were randomly assigned into two groups, the control group which were not given stress and the pre-pregnancy stressed group which were subjected to 3 weeks chronic restraint stress (daily 6h restraint and overnight illumination 2/W).2 days after the last stressor, randomly selected control group and PS group was housed with a male. After about 4 weeks later, the mice gave birth to pups. There were four experimental groups:(1) control group (C), which did not experience chronic stress and pregnancy; (2) stressed only group that did not experience pregnancy (S); (3) partus only group which did not experience prepregnancy stress (P); and (4) stressed plus partus group (SP). Both C and S groups include females which were co-housed with a male but failed to reproduce. Both P and SP groups gave birth to offspring. Then at 3 weeks postpartum, we tested the 4 groups maternal depressive-like behavior, including open field test (OFT),sucrose preference test(SPT), forced swimming test (FST) and novelty suppressed feeding test(NSF), and calcμlate the number of pups and the offspring survival rate.In addition, six from each of the four groups to detect the sucrose consumption from 1 to 12 weeks postpartum, and behavioral test was administrated at 12 weeks postpartum to evaluate the lasting stability of PPD model.2.3 weeks postpartum, western blotting and Q-PCR were used to detect the protein and mRNA expression of hippocampus DISCI, and assay NR1, Akt, mTOR, p70s6k,4E-BP1, GluRl protein expression after behavioral tests; enzyme-linked immunosorbent assay (ELISA) was used to detect corticosterone and estradiol.20 days postpartum, the four groups PPD were randomly to intraperitoneal injection BrdU (75mg/kg,1/2h x 4), taken the brain 24 hours after infusion, using immunohistochemistry to detect hippocampal generation.3. Female Balb/c mice were randomly assigned into control group and pre-pregnancy stressed group, modeling the same way as before. The pre-pregnancy stressed group of mice was subjected to 3 weeks chronic restraint stress (daily 6h restraint and overnight illumination 2/W).2 days after the last stressor, pre-pregnancy stressed group was housed with a male. After about 4 weeks later, the mice gave birth to pups. There were two experimental groups:the control group and PPD model group. Mice randomly were selected 18 mice from the model group and divided into three groups, the model group, YG group and Ket group.20 days postpartum, YG group was administrated acute Yueju Ganmai Dazao (0.1 mL.10g-1 ig), control group and model group were administrated single dose of saline, and Ket group was administrated ketamine (0.1 mL.10g-1 intraperitoneally) as a positive group.24 hours after administration, animal behavioral tests were test, including OFT, SPT, FST, TST and NSF, to assess the antidepressant-like effect. In addition, the model group was randomly divided into three groups, PPD model group, YG group and Ket group, together with the control group,20 days postpartum, animal behavior were test at 5 days after acute drugs respectively, to assess the lasting antidepressant-like effects.4. After behavioral test, the hippocampal expression of Akt, NR1, Akt, mTOR, p70s6k, 4E-BP1, GluRl were detected to study the molecμlar mechanisms of fast antidepressant-like effect of YGResμlts1. At 3 weeks postpartum, there was a significant reduction in sucrose preference in the SP group. Immobility time in FST and TST were significantly increased in the SP group. SP group displayed a significantly increased latency to eat and decreased food consumption in the NSF test. In the OFT, there was no effect on the total distance moved or time spent in the center field. Sucrose preference was significantly reduced from 1 week postpartum and lasted at least for 12 weeks postpartum. Additionally, the number of offspring born to the SP group and their survival ratewas significantly decreased compared to the P group. By 12 weeks postpartum, the deficits were still remarkable in SPT, FST, and TST, NSF. There was no significant behavioral difference between C, S and P groups at any time postpartum.2. At 3 weeks postpartum, DISCI and NR1 expression were significantly increased in the SP group, compared to the S, P and N groups. Furthermore, only the SP group showed decreased phosphorylation of Akt, mTOR,4E-BP1, and p70s6k, and decreased expression of GluRl. Additionally, the number of BrdU-positive cells in the SP group was dramatically reduced, compared to C group. And there was no significant difference on the maternal E2 and CORT.3. At 3 weeks postpartum, a single dose of YG improved the performance of SP group mice in SPT, FST, latency to eat and food consumption in the NSF test compared to vehicle-treated SP group, which was similar to Ket. The antidepressant effects lasted for at least for 5 days.4. Acute YG reversed the changes in the SP group in hippocampal expression of DISC1-NR1-Akt-mTOR signaling proteins, which was similar to Ket.Conclusion1. Pre-pregnancy stress contribute to prolonged PPD-like behavior at 3 weeks postpartum, which showed full spectrum of depressive behaviors, anhedonia, hopelessness, anxiety and reduction of maternal care. And the symptoms lasted at least 12 weeks postpartum. The behavior of this model stable and suitable, which was able to reflect the typical PPD.2. Abnormal Disc1 signaling may play an important role in PPD. Up-regulated DISCI expression by prior chronic stress/depression may have a long-term impact on the onset and maintenance of PPD. Pre-pregnancy stress through activation of DISC1-NR1 to inhibit Akt-mTOR and its downstream substrates p70s6k and 4E-BP1, therefore, reduces the neural plasticity of postsynaptic membrane protein GluRl, decreases the newborn neurons and promotes the occurrence of PPD.3. Acute YG after 24 hours exert fast antidepressant effect on the PPD model, and it could last at least 5 days, which is similar to ketamine.4. Acute YG treatment reversed the up-regμlated expression of DISC1-NR1, and down-regμlated activation of mTOR singaling, including Akt, mtor,4E-BP1 and s6k, which is similar to ketamine. Normalized DISC1-NR1-Akt-mTOR signaling in the PPD-like mice may be the one of the mechanisms of fast antidepressant-like effect of YG. |
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