2 - The Effect of Early and Late Life Chronic Social Stress on the Cellular Morphology of the Spheno-Occipital Synchondrosis in Female Post-natal Mice

Poster Board Number: 2
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Co-authors:

Mizuho Kawasaki - Research Technician, Anthropology, Penn State University; Emily Durham - Post-Doctoral Researcher, Children's Hospital of Philadelphia; Giulia Mazzari - Psychosomatic Medicine and Psychotherapy - Ulm University Medical Center; Frederick Foster - Post-Doctoral Researcher, Anthropology, Penn State University; Abigail Coupe - Anthropology - Penn State University; Melanie Haffner-Luntzer - Institute of Orthopaedic Research and Biomechanics - University of Ulm; Stefan Reber - Psychosomatic Medicine and Psychotherapy - Ulm University Medical Center

Abstract Body :Changes in social status, including social instability, are considered important indicators of health outcomes throughout adolescence and adulthood, with implications for disease prevalence and mortality in humans and other social animals 1,2. Changes in social status activate the hypothalamic-pituitary-adrenal axis, leading to a variety of disease outcomes due to new forms of stress and stress responses 3. Stress plays an important role in healthy bone growth where it can suppress immune response, prevent healing, and affect endochondral ossification 4,5. The effects of stress on the growth and development of the braincase floor warrant special attention, because premature fusion of synchondroses is related to developmental abnormalities in the skull 6, signifying the importance of maintaining standard growth in this region. We aimed to answer the question: What is the effect of chronic social stress during early life and/or later life on the cellular morphology of the spheno-occipital synchondrosis (SOS)? Histological data of the SOS was collected from female mice who experienced only early life stress (n=5; maternal separation, MS), only later life stress (n=5; social instability, SI), both early and late life stress (n=3; MS+SI), or no stress (n=3; control). Cell count, cartilage matrix size, and SOS cartilage size were measured for each specimen and a Kruskal-Wallis test was used to identify differences between groups. Results indicate that the matrix size and SOS cartilage size were the same across all groups, and the null hypothesis was retained. Cell counts were also the same across all groups, however, posthoc tests indicated that the control group and the early-life MS group were significantly different, with the MS group having significantly more nuclei. This suggests a trend towards differences in cellularity of the SOS between these two groups and supports the assertion that stress in early life has a larger effect on cells in the SOS than late-life stress or compounded stress. These results provide insights into how stress impacts the cranium, informing researchers about the interplay between social stress, social status, and human health disparities. More data and careful examination are needed to understand any connections between stress and changes in the growth centers of the skull.1. Herzog, C. J. et al. Neuroscience 159, 982-992 (2009). 2. Snyder-Mackler, N. et al. Science 368, eaax9553 (2020). 3. Yaribeygi, H., et al. EXCLI Journal; 16:Doc1057; ISSN 1611-2156 (2017). 4. Foertsch, S. et al. Dis. Model. Mech. 10, 1399-1409 (2017). 5. Haffner-Luntzer, M. et al. Proc Natl Acad Sci USA 116, 8615-8622 (2019). 6. Cendekiawan, T., et al. Open Anat J 2, 67-75 (2010).