Endogenous oxytocin levels in extracted saliva elevates during breastfeeding correlated with lower postpartum anxiety in primiparous mothers.

BACKGROUND: Breastfeeding in the early postpartum period is expected to have mental benefits for mothers; however, the underlying psychobiological mechanisms remain unclear. Previously, we hypothesized that the release of oxytocin in response to the suckling stimuli during breastfeeding would mediate a calming effect on primiparous mothers, and we examined salivary oxytocin measurements in primiparous mothers at postpartum day 4 using saliva samples without extraction, which was erroneous. Thus, further confirmation of this hypothesis with a precise methodology was needed. METHODS: We collected saliva samples at three time points (baseline, feeding, and post-feeding) to measure oxytocin in 24 primiparous mothers on postpartum day 2 (PD2) and 4 (PD4) across the breastfeeding cycle. Salivary oxytocin levels using both extracted and unextracted methods were measured and compared to determine the qualitative differences. State and trait anxiety and clinical demographics were evaluated to determine their association with oxytocin changes. RESULTS: Breastfeeding elevated salivary oxytocin levels; however, it was not detected to a significant increase in the extraction method at PD4. We found a weak but significant positive correlation between changes in extracted and unextracted oxytocin levels during breastfeeding (feeding minus baseline); there were no other significant positive correlations. Therefore, we used the extracted measurement index for subsequent analysis. We showed that the greater the increase in oxytocin during breastfeeding, the lower the state anxiety, but not trait anxiety. Mothers who exclusively breastfed at the 1-month follow-up tended to be associated with slightly higher oxytocin change at PD2 than those who did not. CONCLUSIONS: Breastfeeding in early postpartum days could be accompanied by the frequent release of oxytocin and lower state anxiety, potentially contributing to exclusive breastfeeding.

Database for exchangeable gene trap clones: pathway and gene ontology analysis of exchangeable gene trap clone mouse lines.

Gene trapping in embryonic stem (ES) cells is a proven method for large-scale random insertional mutagenesis in the mouse genome. We have established an exchangeable gene trap system, in which a reporter gene can be exchanged for any other DNA of interest through Cre/mutant lox-mediated recombination. We isolated trap clones, analyzed trapped genes, and constructed the database for Exchangeable Gene Trap Clones (EGTC) [http://egtc.jp]. The number of registered ES cell lines was 1162 on 31 August 2013. We also established 454 mouse lines from trap ES clones and deposited them in the mouse embryo bank at the Center for Animal Resources and Development, Kumamoto University, Japan. The EGTC database is the most extensive academic resource for gene-trap mouse lines. Because we used a promoter-trap strategy, all trapped genes were expressed in ES cells. To understand the general characteristics of the trapped genes in the EGTC library, we used Kyoto Encyclopedia of Genes and Genomes (KEGG) for pathway analysis and found that the EGTC ES clones covered a broad range of pathways. We also used Gene Ontology (GO) classification data provided by Mouse Genome Informatics (MGI) to compare the functional distribution of genes in each GO term between trapped genes in the EGTC mouse lines and total genes annotated in MGI. We found the functional distributions for the trapped genes in the EGTC mouse lines and for the RefSeq genes for the whole mouse genome were similar, indicating that the EGTC mouse lines had trapped a wide range of mouse genes.

Tamoxifen feeding method is suitable for efficient conditional knockout.

The Cre-driver system is used to generate conditional knockout mice. Tamoxifen inducible Cre-driver mice can be used for spatiotemporal knockout by administration of the drug. A major tamoxifen administration is performed by intraperitoneal administration or oral administration. However, these forced administrations may be damaging to mice. Herein, we have demonstrated an improved method of administering tamoxifen with powdered food to mice. A mouse line expressing the tamoxifen-inducible Cre gene was used ubiquitously in this experiment to evaluate the efficiency of Cre recombination in the whole body. Our method also achieved efficient recombination without causing injury to mice. The X-gal staining intensity of the feeding method was equivalent to that of the intraperitoneal administration method. Furthermore, this method can be used for recombination before birth, or during the fetal period. We recommend researchers to employ this feeding method to administer tamoxifen to minimize the risk of injury to mice.

Developing an instrument to measure climacteric symptoms among Korean and Japanese women.

PURPOSE: The purpose of this study was to construct a measurement instrument for climacteric symptoms among Korean and Japanese women. METHODS: From Dec. 1st of 2003 to March 30th of 2004, in-depth interviews were made with 26 women (15 in Jinju, Korea and 11 in Nagasaki, Japan) aged from 45 to 59 years who had not taken hormone replacement therapy to relieve the climacteric symptoms. A draft questionnaire with 45 items was constructed on the basis of the interview data and literature review. Three obstetricians, three PhDs in nursing science, and a chief nurse who was exclusively in charge of the climacteric management, examined the draft questionnaire to evaluate content validity. After deletions 39 items remained for a preliminary questionnaire. A survey was conducted by using a convenient sampling method in Jinju of Korea and Nagasaki of Japan during the period from April 1st, 2004 to July 10th, 2005. RESULTS: Factor analysis identified 4 factors, which were "mental and psychological symptoms", "physical symptoms", "loss of autonomic nervous system symptoms", "sexual symptoms". These four factors explained 46.9% of total variance. CONCLUSIONS: The results demonstrated that climacteric symptom scale was multidimensional, and the reliability and validity of the scale was supported.

Fetal response to induced maternal emotions.

This study investigated the relationship between fetal movements and acute maternal emotional changes during pregnancy. Two empirically validated feature film clips were used for the external generation of two subjectively and facially well-characterized target emotions: happiness and sadness. We simultaneously monitored separate fetal arm, leg, and trunk movements by means of two ultrasound apparatuses while maternal emotions were manipulated by film clip presentation. The number of fetal arm movements, but not the duration, was increased when pregnant women were being shown a happy film. Both the number and the duration of fetal arm movements decreased with the sad film presentation. Neither the presentation of happiness nor the presentation of sadness affected fetal leg or trunk movements. These findings suggest that induced emotions in pregnant women primarily affect arm movements of their fetuses, and that positive and negative emotions have the opposite effects on fetus movement.