Universitätspublikationen
Refine
Year of publication
- 2020 (2)
Document Type
- Article (1)
- Doctoral Thesis (1)
Language
- English (2) (remove)
Has Fulltext
- yes (2) (remove)
Is part of the Bibliography
- no (2)
Keywords
- social isolation (2) (remove)
Institute
- Biowissenschaften (1)
- Medizin (1)
Across the entire animal kingdom, sociality, i.e. the tendency of individual animals to form a group with conspecifics, is a common trait. Environmental changes have to be met with corresponding, quick adaptations. For social species, the presence of conspecifics is important for survival and if social animals are deprived of access to conspecifics, this can lead to strong and lasting changes on a physiological level as well as behaviour. Gene expression changes responsible for these adaptations have so far not been understood in detail. As social isolation leads to changes on a neuronal level, it is important to investigate the gene expression changes that are induced in the brain. In this thesis, next-generation RNA-sequencing was applied to zebrafish, a well-established model organism characterized by its high degree of companionship. Within the entire brain, gene expression was analysed in zebrafish that were raised either with conspecifis or in isolation, ranging from 5 to 21 days post fertilization. Using this approach, several genes were identified that were downregulated by social isolation. In this thesis, I focused on one of these consistently downregulated genes, parathyroid hormone 2 (pth2). The expression of pth2 was demonstrated to be bidirectionally regulated by the number of conspecifics present and to be responsive to changes in the social environment within 30 minutes. Regulation of pth2 does not occur by visual or chemosensory access to conspecifcs, but is mediated by mechanosensory perception of other fish via the lateral line. In an experiment using an artificial mechanical stimulation paradigm, it was shown that the features necessary to elicit pth2 transcription closely mimick the locomotion of actual zebrafish. Other, similar stimulation paradigms are not capable to induce this transcriptional response.
Suicide represents a major challenge to public mental health. In order to provide empirical evidence for prevention strategies, we hypothesized current levels of low socioeconomic status (SES) and high social isolation (SI) to be linked to increased suicide rates in N = 390 administrative districts since SES and SI are associated with mental illness. Effects of SES on suicide rates were further expected to be especially pronounced in districts with individuals showing high SI levels as SI reduces the reception of social support and moderates the impact of low SES on poor mental health. We linked German Microcensus data to register data on all 149,033 German suicides between 1997 and 2010 and estimated Prentice and Sheppard’s model for aggregate data to test the hypotheses, accounting for spatial effect correlations. The findings reveal increases in district suicide rates by 1.20% (p < 0.035) for 1% increases of district unemployment, suicide rate decreases of −0.39% (p < 0.028) for 1% increases in incomes, increases of 1.65% (p < 0.033) in suicides for 1% increases in one-person-households and increases in suicide rates of 0.54% (p < 0.036) for 1% decreases in single persons’ incomes as well as suicide rate increases of 3.52% (p < 0.000) for 1% increases in CASMIN scores of individuals who moved throughout the year preceding suicide. The results represent appropriate starting points for the development of suicide prevention strategies. For the definition of more precise measures, future work should focus on the causal mechanisms resulting in suicidality incorporating individual level data.