| ObjectivesTo investigate the influence of Quetiapine (QUE) and repetitive transcranial magneticstimulation (rTMS) on the behavior of CUS model rats and the proliferation in thehippocampus and hippocampus-derived neural stem cells (NSCs), and its possiblemechanism.MethodsThe present study was divided into two parts. In the in vivo experiment (Experiment1),we observed the behavioral manifestations, the changes of the protein expressions ofhippocampal brain-derived neurotrophic factor (BDNF),phosphorylated extracellularsignal-regulated protein kinase (pERK1/2) and extracellular signal-regulated kinase (ERK),and the influence of hippocampal neurogenesis in the rats subjected to chronicunpredictable stress. In the in vitro experiment(Experiment2), we explored the expressionalterationsof these proteins and the proliferation of NSCs after pretreatment with orwithnot U0126.In Experiment1,rats were randomly divided into sham group, CUS group, CUS+ rTMS group, CUS+QUE group and CUS+QUE+rTMS group. The rats in the shamgroup were kept in their home cages for4weeks, and then subjected to sham rTMStreatments and injected intraperitoneally with1%DMSO in saline as a vehicle for7days.After4weeks of the establishment of CUS model, the rats in CUS group received shamrTMS treatments and vehicle saline for7consecutive days, the rats in CUS+rTMS groupwere subjected to real rTMS treatments and vehicle saline for7days, the rats in the CUS+QUE group received sham rTMS treatments and quetiapine for7days, and the rats inthe CUS+rTMS+QUE group were subjected to real rTMS treatments and quetiapine for7days.In Experiment2, theneurospheresformed by the hippocampus-derived neural stem cellswere randomly divided into eight groups: Vehicle group, rTMS group, QUE group, rTMS+QUE group, Vehicle+U0126group, rTMS+U0126group, QUE+U0126group, andrTMS+QUE+U0126group.The NSCs in the last4groups were pretreated with2.5μMU0126(applied in serum-free medium1h prior to the addition of QUE or vehiclesaline).In drug intervention groups,1μMof quetiapine was added to the medium. In vehicletreated groups, vehicle saline was added to the same cultural medium. NSCs ineverygroup were treated with5μM Brdu.The trains of rTMS were administered daily for2days in rTMS treated groups,500pulses per day.ResultsThere was a significant decrease in sucrose preferencea decrease of the percentage oftime spent exploring the center of the arena, and a significant increase in the immobilitytime in the CUS rats compared with those of the sham group. Furthermore, the proteinexpressions of BDNF and pERK1/2and the cell proliferation rates in the hippocampus ofCUS rats were significantly decreased. Treatment with rTMS or QUE ameliorated thesedecreases, and QUE combined with rTMS have greatereffects compared with eachsingletreatment. Interestingly, U0126can block these benefits. The details of the resultswerereported as follow.Experiment11. Compared with sham group, the rats exposed to CUS showed an increase in the immobility time in the FST (P<0.001), a decrease in the percentage of time spentexploring the center of the arena (P=0.002) and a decrease in sucrose preference inSPT (P <0.001), a decline in the protein expression of BDNF and pERK1/2(P<0.001) and a decrease in the number of BrdU-positive (BrdU+) cells in thehippocampus (P<0.001).2. Compared with CUS group, the rats in CUS+rTMS, CUS+QUE, and CUS+QUE+rTMStreatment groups had a decrease in the immobility time (all P<0.001) and anincrease in sucrose preference (all P<0.01). rTMS or QUE significantly increasedthe expression levels of BDNF and pERK1/2in the hippocampus (all P<0.05) andthe amount of BrdU+cells in the dentate gyrus of the hippocampus (all P<0.05).However, there was no significant difference of the level of hippocampal ERK1/2among all groups (F=1.240, P=0.326).Compared with the CUS group, thepercentage of time spent exploring the center of the CUS+rTMS groupsdidn’tchange much (P=0.822), but treatment with QUE or QUE combined rTMSsignificantly increased this percentage (P=0.040; P=0.009).3. Comparedto CUS+rTMS group, combining treatment of rTMS and QUEsignificantly increased the percentage of time spent exploring the center of the arena(P=0.016), the sucrose preference rates (P=0.031), the protein levels of BDNF (P<0.001) and pERK1/2(P=0.006) in the hippocampus, and the amount of BrdU+cellsin the dentate gyrus of the hippocampus (P=0.006). Compared with CUS+QUEgroup, the rats in CUS+QUE+rTMS group showed a decrease in the immobilitytime (P=0.041), and increasesofthe sucrose preference rates (P=0.047) and thenumbers of BrdU+cells in the hippocampus (P=0.024).Experiment21. After U0126intervention, the ratio of BDNF/β-actin and pERK1/2/β-actin, the numberof BrdU+cells and the viability of hippocampus-derived NSCs were all significantlyincreased (all P<0.05). And the results showed that there were no significantdifferences among Vehicle+U0126, rTMS+U0126, QUE+U0126andrTMS+QUE+U0126groups of theabove mentioned indicators. 2. Compared with Vehicle group, the NSCs in rTMS group, QUE group and rTMS+QUE group all had an increase of the ratio of BDNF/β-actin and pERK1/2/β-actin, thenumber of BrdU+cells and the cell viability (all P<0.05).3. Compared with rTMS group, the ratio of BDNF/β-actin was increasedin rTMS+QUEgroup (P=0.005); The NSCs in rTMS+QUE group have a higher ratio of BrdU+/PIcells and greater cell viability compared with those of the rTMS group and the QUEgroup (all P<0.05).ConclusionThe results showed that QUE and rTMS ameliorated depressive-like behavior of CUSmodel rats, increased hippocampal neurogenesis of rats and promoted the proliferation ofhippocampal derived NSCs. QUE and rTMS had synergistic effects. These effects may bemediated by ERK/BDNF/neurogenesis pathways. |
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