Aberrant Hippocampal Development in Early‑onset Mental Disorders and Promising Interventions:Evidence from a Translational Study

Early-onset mental disorders are associated with disrupted neurodevelopmental processes during adolescence.The methylazoxymethanol acetate(MAM)animal model,in which disruption in neurodevelopmental processes is induced,mimics the abnormal neurodevelopment associated with early-onset mental disorders from an etiological perspective.We conducted longitudinal structural magnetic resonance imaging(MRI)scans during childhood,adolescence,and adulthood in MAM rats to identify specific brain regions and critical windows for intervention.Then,the effect of repetitive transcranial magnetic stimulation(rTMS)intervention on the target brain region during the critical window was investigated.In addition,the efficacy of this intervention paradigm was tested in a group of adolescent patients with early-onset mental disorders(diagnosed with major depressive disorder or bipolar disorder)to evaluate its clinical translational potential.The results demonstrated that,compared to the control group,the MAM rats exhibited significantly lower striatal volume from childhood to adulthood(all P<0.001).In contrast,the volume of the hippocampus did not show significant differences during childhood(P>0.05)but was significantly lower than the control group from adolescence to adulthood(both P<0.001).Subsequently,rTMS was applied to the occipital cortex,which is anatomically connected to the hippocampus,in the MAM models during adolescence.The MAM-rTMS group showed a significant increase in hippocampal volume compared to the MAM-sham group(P<0.01),while the volume of the striatum remained unchanged(P>0.05).In the clinical trial,adolescents with early-onset mental disorders showed a significant increase in hippocampal volume after rTMS treatment compared to baseline(P<0.01),and these volumetric changes were associated with improvement in depressive symptoms(r=−0.524,P=0.018).These findings highlight the potential of targeting aberrant hippocampal development during adolescence as a viable intervention for earlyonset mental disorders with neurodevelopmental etiology as well as the promise of rTMS as a therapeutic approach for mitigating aberrant neurodevelopmental processes and alleviating clinical symptoms.

Disruption of Planar Cell Polarity Pathway Attributable to Valproic Acid-Induced Congenital Heart Disease through Hdac3 Participation in Mice

Background： Valproic acid （VPA） exposure during pregnancy has been proven to contribute to congenital heart disease （CHD）. Our previous findings implied that disruption of planar cell polarity （PCP） signaling pathway in cardiomyocytes might be a factor for the cardiac teratogenesis of VPA. In addition, the teratogenic ability of VPA is positively correlated to its histone deacetylase （HDAC） inhibition activity. This study aimed to investigate the effect of the VPA on cardiac morphogenesis, HDAC1/2/3, and PCP key genes （Vangl2/Scrib/Rac 1）, subsequently screening out the specific HDACs regulating PCP pathway. Methods： VPA was administered to pregnant C57BL mice at 700 mg/kg intraperitoneally on embryonic day ! 0.5. Dams were sacrificed on E15.5, and death/absorption rates of embryos were evaluated. Embryonic hearts were observed by hematoxylin-eosin staining to identify cardiac abnormalities. H9C2 cells （undifferentiated rat cardiomyoblasts） were transfected with Hdac1/2/3 specific small interfering RNA （siRNA）. Based on the results of siRNA transfection, cells were transfected with Hdac3 expression plasmid and subsequently mock-treated or treated with 8.0 mmol/L VPA. Hdac1/2/3 as well as Vangl2/Scrib/Racl mRNA and protein levels were determined by real-time quantitative polymerase chain reaction and Western blotting, respectively. Total HDAC activity was detected by colorimetric assay.Results： VPA could induce CHD （P 〈 0.001） and inhibit mRNA or protein expression of Hdac1/2/3 as well as Vangl2/Scrib in fetal hearts, in association with total Hdac activity repression （all P 〈 0.05）. In vitro, Hdac3 inhibition could significantly decrease Vangl2/Scrib expression （P 〈 0.01 ）, while knockdown of Hdac 1/2 had no influence （P 〉 0.05）, VPA exposure dramatically decreased the expression of Vanlg2/Scrib together with Hdac activity （P 〈 0.01 ）, while overexpression of Hdac3 could rescue the VPA-induced inhibition （P 〉 0.05）. Conclusion： VPA could inhibit Hdac1/2/3, Vang12/Scrib, or total Hdac activity both in vitro and in vivo and Hdac3 might participate in the process of VPA-induced cardiac developmental anomalies.

Effect of Histone Deacetylase Inhibition on the Expression of Multidrug Resistance-associated Protein 2 in a Human Placental Trophoblast Cell Line

Background： Placental multidrug resistance-associated protein 2 （MRP2）, encoded by ABCC2 gene in human, plays a significant role in regulating drugs＇ transplacental transfer rates. Studies o11 placental MRP2 regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the roles of epigenetic mechanisms in regulating placental drug transporters are still unclear. This study aimed to investigate the effect of histone deacetylases （HDACs） inhibition on MRP2 expression in the placental trophoblast cell line and to explore whether HDAC 1/2/3 are preliminarily involved in this process. Methods： The human choriocarcinoma-derived trophoblast cell line （Bewo cells） was treated with the HDAC inhibitors-trichostatin A （TSA） at different concentration gradients of 0.5, 1.0, 3.0, and 5.0 μmol/L. Cells were harvested after 24 and 48 h treatment. Small interfering RNA （siRNA） specific for HDACI/HDAC2/HDAC3 or control siRNA was transfected into cells. Total HDAC activity was detected by colorimetric assay kits. HDAC 1/2/3/ABCC2 messenger RNA （mRNA） and protein expressions were determined by real-time quantitative polymerase chain reaction and Western-blot analysis, respectively. Immunofluorescence for MRP2 protein expression was visualized and assessed using an immunofluorescence microscopy and ImageJ software, respectively. Results： TSA could inhibit total HDAC activity and HDAC 1/2/3 expression in company with increase ofM RP2 expression in Bewo cells. Reduction of HDAC 1 protein level was noted after 24 h of TSA incubation at 1.0, 3.0, and 5.0 μmol/L （vs. vehicle group, all P 〈 0.001 ）, accompanied with dose-dependent induction of MRP2 expression （P = 0.045 for 1.0 μmol/L, P = 0.001 for 3.0 μmol/L, and P 〈 0.001 for 5.0 μmol/L）, whereas no significant diferences in MRP2 expression were noted after HDAC2/3 silencing. Fluorescent micrograph images of MRP2 protein were expressed on the cell membrane. The fluorescent intensities of MRP2 in the control, HDAC2, and HDAC3 siRNA-transfected cells weir week, and no significant differences were noticed among these three groups （all P 〉 0.05）. However, MRP2 expression was remarkably elevated in H DAC1 siRNA-transfected cells, which displayed an almost 3.19-fold changes in comparison with the control siRNA-transfected cells （P 〈 0.001 ）. Conclusions： HDACs inhibition could up-regulate placental MRP2 expression in ritzy, and HDAC 1 was probably to be involved in this process.