Physical Activity Reduces Clinical Symptoms and Restores Neuroplasticity in Major Depression.

Major depressive disorder (MDD) is the most common mental disorder and deficits in neuroplasticity are discussed as one pathophysiological mechanism. Physical activity (PA) enhances neuroplasticity in healthy subjects and improves clinical symptoms of MDD. However, it is unclear whether this clinical effect of PA is due to restoring deficient neuroplasticity in MDD. We investigated the effect of a 3-week PA program applied on clinical symptoms, motor excitability and plasticity, and on cognition in patients with MDD (N = 23), in comparison to a control intervention (CI; N = 18). Before and after the interventions, the clinical symptom severity was tested using self- (BDI-II) and investigator- (HAMD-17) rated scales, transcranial magnetic stimulation (TMS) protocols were used to test motor excitability and paired-associative stimulation (PAS) to test long-term-potentiation (LTP)-like plasticity. Additionally, cognitive functions such as attention, working memory and executive functions were tested. After the interventions, the BDI-II and HAMD-17 decreased significantly in both groups, but the decrease in HAMD-17 was significantly stronger in the PA group. Cognition did not change notably in either group. Motor excitability did not differ between the groups and remained unchanged by either intervention. Baseline levels of LTP-like plasticity in the motor cortex were low in both groups (PA: 113.40 ± 2.55%; CI: 116.83 ± 3.70%) and increased significantly after PA (155.06 ± 10.48%) but not after CI (122.01 ± 4.1%). Higher baseline BDI-II scores were correlated with lower levels of neuroplasticity. Importantly, the more the BDI-II score decreased during the interventions, the stronger did neuroplasticity increase. The latter effect was particularly strong after PA (r = -0.835; p < 0.001). The level of neuroplasticity related specifically to the psychological/affective items, which are tested predominantly in the BDI-II. However, the significant clinical difference in the intervention effects was shown in the HAMD-17 which focuses more on somatic/neurovegetative items known to improve earlier in the course of MDD. In summary, PA improved symptoms of MDD and restored the deficient neuroplasticity. Importantly, both changes were strongly related on the individual patients' level, highlighting the key role of neuroplasticity in the pathophysiology and the clinical relevance of neuroplasticity-enhancing interventions for the treatment of MDD.

Differences in embryo quality are associated with differences in oocyte composition: a proteomic study in inbred mice.

Current models of early mouse development assign roles to stochastic processes and epigenetic regulation, which are considered to be as influential as the genetic differences that exist between strains of the species Mus musculus. The aim of this study was to test whether mouse oocytes vary from each other in the abundance of gene products that could influence, prime, or even predetermine developmental trajectories and features of derivative embryos. Using the paradigm of inbred mouse strains, we quantified 2010 protein groups (SILAC LC-MS/MS) and 15205 transcripts (RNA deep sequencing) present simultaneously in oocytes of four strains tested (129/Sv, C57Bl/6J, C3H/HeN, DBA/2J). Oocytes differed according to donor strain in the abundance of catalytic and regulatory proteins, as confirmed for a subset (bromodomain adjacent to zinc finger domain, 1B [BAZ1B], heme oxygenase 1 [HMOX1], estrogen related receptor, beta [ESRRB]) via immunofluorescence in situ. Given a Pearson's r correlation coefficient of 0.18-0.20, the abundance of oocytic proteins could not be predicted from that of cognate mRNAs. Our results document that a prerequisite to generate embryo diversity, namely the different abundances of maternal proteins in oocytes, can be studied in the model of inbred mouse strains. Thus, we highlight the importance of proteomic quantifications in modern embryology. All MS data have been deposited in the ProteomeXchange with identifier PXD001059 (http://proteomecentral.proteomexchange.org/dataset/PXD001059).

DNA replication is an integral part of the mouse oocyte's reprogramming machinery.

Many of the structural and mechanistic requirements of oocyte-mediated nuclear reprogramming remain elusive. Previous accounts that transcriptional reprogramming of somatic nuclei in mouse zygotes may be complete in 24-36 hours, far more rapidly than in other reprogramming systems, raise the question of whether the mere exposure to the activated mouse ooplasm is sufficient to enact reprogramming in a nucleus. We therefore prevented DNA replication and cytokinesis, which ensue after nuclear transfer, in order to assess their requirement for transcriptional reprogramming of the key pluripotency genes Oct4 (Pou5f1) and Nanog in cloned mouse embryos. Using transcriptome and allele-specific analysis, we observed that hundreds of mRNAs, but not Oct4 and Nanog, became elevated in nucleus-transplanted oocytes without DNA replication. Progression through the first round of DNA replication was essential but not sufficient for transcriptional reprogramming of Oct4 and Nanog, whereas cytokinesis and thereby cell-cell interactions were dispensable for transcriptional reprogramming. Responses similar to clones also were observed in embryos produced by fertilization in vitro. Our results link the occurrence of reprogramming to a previously unappreciated requirement of oocyte-mediated nuclear reprogramming, namely DNA replication. Nuclear transfer alone affords no immediate transition from a somatic to a pluripotent gene expression pattern unless DNA replication is also in place. This study is therefore a resource to appreciate that the quest for always faster reprogramming methods may collide with a limit that is dictated by the cell cycle.

Maternal age effect on mouse oocytes: new biological insight from proteomic analysis.

The long-standing view of 'immortal germline vs mortal soma' poses a fundamental question in biology concerning how oocytes age in molecular terms. A mainstream hypothesis is that maternal ageing of oocytes has its roots in gene transcription. Investigating the proteins resulting from mRNA translation would reveal how far the levels of functionally available proteins correlate with mRNAs and would offer novel insights into the changes oocytes undergo during maternal ageing. Gene ontology (GO) semantic analysis revealed a high similarity of the detected proteome (2324 proteins) to the transcriptome (22 334 mRNAs), although not all proteins had a cognate mRNA. Concerning their dynamics, fourfold changes of abundance were more frequent in the proteome (3%) than the transcriptome (0.05%), with no correlation. Whereas proteins associated with the nucleus (e.g. structural maintenance of chromosomes and spindle-assembly checkpoints) were largely represented among those that change in oocytes during maternal ageing; proteins associated with oxidative stress/damage (e.g. superoxide dismutase) were infrequent. These quantitative alterations are either impoverishing or enriching. Using GO analysis, these alterations do not relate in any simple way to the classic signature of ageing known from somatic tissues. Given the lack of correlation, we conclude that proteome analysis of mouse oocytes may not be surrogated with transcriptome analysis. Furthermore, we conclude that the classic features of ageing may not be transposed from somatic tissues to oocytes in a one-to-one fashion. Overall, there is more to the maternal ageing of oocytes than mere cellular deterioration exemplified by the notorious increase of meiotic aneuploidy.

Effects of embryo culture media do not persist after implantation: a histological study in mice.

STUDY QUESTION: Is post-implantation embryonic development after blastocyst transfer affected by exposure to different assisted reproduction technology (ART) culture media? SUMMARY ANSWER: Fetal development and placental histology of ART embryos cultured in vitro in different ART media was not impaired compared with embryos grown in vivo. WHAT IS KNOWN ALREADY: The application of different in vitro culture (IVC) media for human ART has an effect on birthweight of newborns. In the mouse model, differences in blastocyst formation were reported after culture in different ART media. Moreover, abnormalities in the liver and heart have been detected as a result of suboptimal IVC conditions. STUDY DESIGN, SIZE, DURATION: Fertilized oocytes from inbred and outbred breeding schemes were retrieved and either immediately transferred to foster mothers or incubated in control or human ART culture media up to the blastocyst stage prior to transfer. Placental and fetal anatomy and particularly bone development were evaluated. PARTICIPANTS/MATERIALS, SETTING, METHODS: B6C3F1 female mice were used as oocyte donors after ovulation induction. C57Bl/6 and CD1 males were used for mating and CD1 females as foster mothers for embryo transfer. Fertilized oocytes were recovered from mated females and incubated in sequential human ART media (ISM1/ISM2 and HTF/Multiblast), in control media [KSOM(aa) and Whitten's medium] or grown in utero without IVC (zygote control). As in vivo, control B6C3F1 females were superovulated and left untreated. Fetuses and placentae were isolated by Caesarean section and analysed at 18.5 days post-coitum (dpc) for placenta composition and at 15.5 dpc for body weight, crown-rump length (CRL), fetal organ development, morphological development, total bone length and extent of bone ossification. MAIN RESULTS AND THE ROLE OF CHANCE: No major differences in the number of implantation sites or in histological appearance of the placentae were detected. CRL of KSOM(aa) fetuses was higher compared with zygote control and Whitten's medium. Histological analysis of tissue sections revealed no gross morphological differences compared with the in vitro groups or in vivo controls. Furthermore, no changes in skeletal development and degree of ossification were observed. However, fibula and tibia of ISM1/ISM2 fetuses were longer than the respective ones from in vivo fetuses. LIMITATIONS, REASONS FOR CAUTION: Findings in the mouse embryo and fetus may not be fully transferable to humans. In addition to skeletal development and placentation, there may be other parameters, e.g. on the molecular level which respond to IVC in ART media. Some comparisons have limited statistical power. WIDER IMPLICATIONS OF THE FINDINGS: Our data suggest that once implantation is achieved, subsequent post-implantation development unfolds normally, resulting in healthy fetuses. With mouse models, we gather information for the safety of human ART culture media. Our mouse study is reassuring for the safety of ART conditions on human embryonic development, given the lack of bold detrimental effects observed in the mouse model. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Deutsche Forschungsgemeinschaft (BO 2540/4-1 and SCHL 394/9-1) and by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (S.L.G.); Bilateral grant NWO-DFG 63-258. None of the authors has any conflict of interest to declare. TRIAL REGISTRATION NUMBER: Not applicable.

Reprogramming of two somatic nuclei in the same ooplasm leads to pluripotent embryonic stem cells.

The conversion of the nuclear program of a somatic cell from a differentiated to an undifferentiated state can be accomplished by transplanting its nucleus to an enucleated oocyte (somatic cell nuclear transfer [SCNT]) in a process termed "reprogramming." This process achieves pluripotency and occasionally also totipotency. Exploiting the obstacle of tetraploidy to full development in mammals, we show that mouse ooplasts transplanted with two somatic nuclei simultaneously (double SCNT) support preimplantation development and derivation of novel tetraploid SCNT embryonic stem cells (tNT-ESCs). Although the double SCNT embryos do not recapitulate the expression pattern of the pluripotency-associated gene Oct4 in fertilized embryos, derivative tNT-ESCs have characteristics of genuine pluripotency: in vitro they differentiate into neurons, cardiomyocytes, and endodermal cells; in vivo, tNT-ESCs form teratomas, albeit at reduced rates compared to diploid counterparts. Global transcriptome analysis revealed only few specific alterations, for example, in the quantitative expression of gastrulation-associated genes. In conclusion, we have shown that the oocyte's reprogramming capacity is in excess of a single nucleus and that double nucleus-transplanted embryos and derivative ESCs are very similar to their diploid counterparts. These results have key implications for reprogramming studies based on pluripotency: while reprogramming in the tetraploid state was known from fusion-mediated reprogramming and from fetal and adult hepatocyte-derived induced pluripotent stem cells, we have now accomplished it with enucleated oocytes.

ART culture conditions change the probability of mouse embryo gestation through defined cellular and molecular responses.

STUDY QUESTION: Do different human ART culture protocols prepare embryos differently for post-implantation development? SUMMARY ANSWER: The type of ART culture protocol results in distinct cellular and molecular phenotypes in vitro at the blastocyst stage as well as subsequently during in vivo development. WHAT IS KNOWN ALREADY: It has been reported that ART culture medium affects human development as measured by gestation rates and birthweights. However, due to individual variation across ART patients, it is not possible as yet to pinpoint a cause-effect relationship between choice of culture medium and developmental outcome. STUDY DESIGN, SIZE, DURATION: In a prospective study, 13 human ART culture protocols were compared two at a time against in vivo and in vitro controls. Superovulated mouse oocytes were fertilized in vivo using outbred and inbred mating schemes. Zygotes were cultured in medium or in the oviduct and scored for developmental parameters 96 h later. Blastocysts were either analyzed or transferred into fosters to measure implantation rates and fetal development. In total, 5735 fertilized mouse oocytes, 1732 blastocysts, 605 fetuses and 178 newborns were examined during the course of the study (December 2010-December 2011). PARTICIPANTS/MATERIALS, SETTING, METHODS: Mice of the B6C3F1, C57Bl/6 and CD1 strains were used as oocyte donors, sperm donors and recipients for embryo transfer, respectively. In vivo fertilized B6C3F1 oocytes were allowed to cleave in 13 human ART culture protocols compared with mouse oviduct and optimized mouse medium (KSOM(aa)). Cell lineage composition of resultant blastocysts was analyzed by immunostaining and confocal microscopy (trophectoderm, Cdx2; primitive ectoderm, Nanog; primitive endoderm, Sox17), global gene expression by microarray analysis, and rates of development to midgestation and to term. MAIN RESULTS AND THE ROLE OF CHANCE: Mouse zygotes show profound variation in blastocyst (49.9-91.9%) and fetal (15.7-62.0%) development rates across the 13 ART culture protocols tested (R(2)= 0.337). Two opposite protocols, human tubal fluid/multiblast (high fetal rate) and ISM1/ISM2 (low fetal rate), were analyzed in depth using outbred and inbred fertilization schemes. Resultant blastocysts show imbalances of cell lineage composition; culture medium-specific deviation of gene expression (38 genes, ≥ 4-fold) compared with the in vivo pattern; and produce different litter sizes (P ≤ 0.0076) after transfer into fosters. Confounding effects of subfertility, life style and genetic heterogeneity are reduced to a minimum in the mouse model compared with ART patients. LIMITATIONS, REASONS FOR CAUTION: This is an animal model study. Mouse embryo responses to human ART media are not transferable 1-to-1 to human development due to structural and physiologic differences between oocytes of the two species. WIDER IMPLICATIONS OF THE FINDINGS: Our data promote awareness that human ART culture media affect embryo development. Effects reported here in the mouse may apply also in human, because no ART medium presently available on the market has been optimized for human embryo development. The mouse embryo assay (MEA), which requires ART media to support at least 80% blastocyst formation, is in need of reform and should be extended to include post-implantation development.