Biology subjects

Kirschbaum, C.

Publications and source records attributed to Kirschbaum, C..

3 recordsLinked to original sources

bioRxiv2021

Dynamic behavior of cell-free mitochondrial DNA in human saliva

Mitochondria contain their own genome that can be released in multiple biofluids such as blood and cerebrospinal fluid, as cell-free mitochondrial DNA (cf-mtDNA). In clinical studies, single measures of blood cf-mtDNA predict mortality, and higher cf-mtDNA levels are associated with mental and physical stress. However, the dynamics of cf-mtDNA has not been defined, and whether it can be measured non-invasively like other neuroendocrine markers in saliva has not been examined. Here we report cf-mtDNA in human saliva and establish its natural within-person dynamic behavior across multiple weeks. In a small proof-of-principle cohort of healthy adults, we first develop an approach to rapidly quantify salivary cf-mtDNA without DNA extraction, and demonstrate the existence of saliva cf-mtDNA. We then deploy this approach to perform an intensive repeated-measures analysis of two healthy men studied at 4 daily timepoints over 53-60 consecutive days (n=212-220 observations each) with parallel measures of steroid hormones, self-reported daily mood, and health-related behaviors. Salivary cf-mtDNA exhibited a robust awakening response reaching up to two orders of magnitude 30-45 minutes after awakening, varied from day-to-day, and moderately correlated with the cortisol awakening response. No consistent association with self-reported daily mood/health-related behaviors were found, although this requires further examination in more extensive studies. Dynamic variation in cf-mtDNA was inversely related with salivary interleukin 6 (IL6), inconsistent with a pro-inflammatory effect of salivary cf-mtDNA. The highly dynamic behavior of salivary cf-mtDNA opens the door to non-invasive studies examining the relevance of mtDNA signaling in relation to human health.

molecular biology↗

bioRxiv2020

Contemplative mental training reduces hair glucocorticoid levels in a randomized clinical trial

ObjectiveThis study had the objective to investigate the effect of regular contemplative mental training on endocrine indices of long-term stress. MethodsAn open-label efficacy trial comprising three distinct 3-month modules targeting attention and interoception, socio-affective or socio-cognitive abilities through dyadic exercises and secularised meditation practices was designed and carried out in 332 healthy meditation-naive adults. Participants underwent the training for up to 9 months or were assigned to a retest control cohort. Chronic stress indices were assayed at four timepoints, i.e., pre-training and following each module. The main outcome measures were cortisol and cortisone concentration in hair and self-reported chronic stress ResultsN=362 initial individuals were randomized, of whom n=30 dropped out before study initiation, n=4 before first sampling and n=2 were excluded. N=99 participants did not provide hair samples. Data from three separate training cohorts revealed consistent decreases in hair cortisol and cortisone levels over the training period. This effect increased with practice frequency, was independent of training content and not associated with change in self-reported chronic stress. ConclusionsOur results point to the reduction of long-term cortisol exposure as a mechanism via which contemplative mental training may exert positive effects on practitioners health. Trial registrationClinicalTrials.gov identifier: NCT01833104

molecular biology↗

bioRxiv2020

Women show enhanced attractiveness ratings and neural processing of male faces associated with male chemosensory signals

There is growing evidence that humans use olfactory chemosensory signals for social communication, but their role in affective associative learning is largely unknown. To examine this, women implicitly learned face-odor associations by pairing different neutral male faces with either a male chemosignal presumably involved in human mating behavior (dissolved {Delta}4,16-androstadien-3-one, "AND"), a pleasant smell (dissolved vanillin) or the neutral solvent alone. After learning, women rated faces previously paired with AND or vanillin as more attractive than faces paired with solvent, even though they were unable to identify the contingency of face-odor pairings above chance level. On a neurophysiological level, both AND- and vanillin-associated faces evoked stronger magnetoencephalographic correlates of enhanced emotional attention than solvent-associated faces at early (<120 ms) and mid-latency (140-270 ms) processing stages. This study stresses the role of AND as a human chemosignal in implicit social communication and demonstrates its effectiveness in modulating emotional learning.

neuroscience↗