Psychoneuroendocrinology
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Psychoneuroendocrinology · Aug 2019
Acute psychological stress increases serum circulating cell-free mitochondrial DNA.
Intrinsic biological mechanisms transduce psychological stress into physiological adaptation that requires energy, but the role of mitochondria and mitochondrial DNA (mtDNA) in this process has not been defined in humans. Here, we show that similar to physical injury, exposure to psychological stress increases serum circulating cell-free mtDNA (ccf-mtDNA) levels. ⋯ Collectively, these findings provide evidence that acute psychological stress induces ccf-mtDNA and implicate neuroendocrine signaling as a potential trigger for ccf-mtDNA release. Further controlled work is needed to confirm that observed increases in ccf-mtDNA result from stress exposure and to determine the functional significance of this effect.
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Psychoneuroendocrinology · Aug 2019
Serotonin transporter gene methylation predicts long-term cortisol concentrations in hair.
Epigenetic signatures, such as DNA methylation (DNAM), have been implicated in long-term dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis and related health risks. Based on a wealth of neuroendocrine studies on genetic polymorphisms in the serotonin transporter gene (SLC6A4), this locus constitutes a key candidate to explore associations of DNAM patterns and HPA-axis functioning. The few studies addressing this link so far exclusively relied on spot measurements of HPA-axis activity, which may not adequately reflect cortisol output over prolonged periods of time. ⋯ Comparable to the pattern we had previously observed concerning cortisol stress reactivity, the S allele relates to increased HCC in individuals displaying low levels of SLC6A4 DNAM. By contrast, no such effect occurred under conditions of high SLC6A4 DNAM, indicating that epigenetic changes may compensate for genotype-dependent differences in long-term cortisol output. Together, respective findings support the idea of an epigenetic contribution to long-term HPA-axis activity and further highlight the usefulness of combining genetic and epigenetic information in future neuroendocrine studies.