Ghrelin is related to lower brain reward activation during touch

The gut hormone ghrelin drives food motivation and increases food intake, but it is also involved in the anticipation of and response to rewards other than food. This pre-registered study investigated how naturally varying ghrelin concentrations affect the processing of touch as a social reward in humans. Sixty-seven volunteers received slow caressing touch (so-called CT-targeted touch) as a social reward and control touch on their shins during 3T functional imaging on two test days. On one occasion, participants were fasted, and on another, they received a meal. On each occasion, plasma ghrelin was measured at three time points. All touch was rated as more pleasant after the meal, but there was no association between ghrelin concentrations and pleasantness. CT-targeted touch was rated as the most pleasant and activated somatosensory and reward networks (whole brain). A region-of-interest in the right medial orbitofrontal cortex (mOFC) showed lower activation during all touches, the higher the ghrelin concentrations were. During CT-targeted touch, a larger satiety response (ghrelin decrease after the meal) was associated with higher mOFC activation, and this mOFC activation was associated with higher experienced pleasantness. Overall, higher ghrelin concentrations appear to be related to a lower reward value for touch. Ghrelin may reduce the value of social stimuli, such as touch, to promote food search and intake in a state of low energy. This suggests that the role of ghrelin goes beyond assigning value to food reward.publishedVersio

Stress responses to repeated captures in a wild ungulate

While capture-mark-recapture studies provide essential individual-level data in ecology, repeated captures and handling may impact animal welfare and cause scientific bias. Evaluating the consequences of invasive methodologies should be an integral part of any study involving capture of live animals. We investigated short- and long-term stress responses to repeated captures within a winter on the physiology, behaviour, and reproductive success of female Svalbard reindeer (Rangifer tarandus platyrhynchus). Short-term responses were evaluated using serum concentrations of glucocorticoids and catecholamines during handling, and post-release recovery times in heart rate and activity levels. Repeated captures were associated with an increase in measured catecholamines and glucocorticoids, except cortisone, and delayed recovery in heart rate but not activity. Four months later, in summer, individuals captured repeatedly in winter exhibited a small increase in behavioural response to human disturbance and had a lower probability of being observed with a calf, compared to animals not captured, or captured only once. Our findings imply that single annual capture events have no significant negative consequences for Svalbard reindeer, but repeated captures within a season may impact offspring survival in the same year. Such unanticipated side effects highlight the importance of addressing multiple indicators of animal responses to repeated captures

Lack of association between the chemokine receptor 5 polymorphism CCR5delta32 in rheumatoid arthritis and juvenile idiopathic arthritis

<p>Abstract</p> <p>Background</p> <p>The chemokine receptor CCR5 has been detected at elevated levels on synovial T cells, and a 32 bp deletion in the <it>CCR5 </it>gene leads to a non-functional receptor. A negative association between the <it>CCR5Δ32 </it>and rheumatoid arthritis (RA) has been reported, although with conflicting results. In juvenile idiopathic arthritis (JIA), an association with CCR5 was recently reported. The purpose of this study was to investigate if the <it>CCR5Δ32 </it>polymorphism is associated with RA or JIA in Norwegian cohorts.</p> <p>Methods</p> <p>853 RA patients, 524 JIA patients and 658 controls were genotyped for the <it>CCR5Δ32 </it>polymorphism.</p> <p>Results</p> <p>The <it>CCR5Δ32 </it>allele frequency was 11.5% in the controls vs. 10.4% in RA patients (OR = 0.90; <it>P </it>= 0.36) and 9.7% in JIA patients (OR = 0.85; <it>P </it>= 0.20). No decreased homozygosity was observed for <it>CCR5Δ32</it>, as previously suggested.</p> <p>Conclusion</p> <p>Our data do not support an association between the <it>CCR5Δ32 </it>allele and Norwegian RA or JIA patients. Combining our results with those from a recently published meta-analysis still provide evidence for a role for <it>CCR5Δ32 </it>in RA, albeit substantially weaker than the effect first reported.</p

Genetic evidence for a contribution of Native Americans to the early settlement of Rapa Nui (Easter Island)

Available evidence strongly suggests that the first to settle on Rapa Nui were Polynesians arriving from the west around AD 1200-1253. There are, however, also signs of an early contact between Rapa Nui and South America, but genetic evidence of an early contribution of Native Americans to the peopling of Rapa Nui has until recently been lacking. In this review our own genetic studies of blood-derived DNA collected on Rapa Nui since 1971 are summarized. For the first time human molecular genetic data are obtained which strongly suggest that some Native Americans arrived early at Rapa Nui, probably as early as AD 1280-1495. Whether they sailed directly from South America to Rapa Nui on their own rafts or whether they came with Polynesians returning from visits to South America cannot be established by our studies, but the latter possibility may be the most likely given other evidence of early visits by Polynesians to South America. In any case, our data suggest that some Native Americans arrived Rapa Nui not long after its first settlement by Polynesians, but long before the island was discovered by Europeans in 1722. Native Americans may therefore have had an influence on the early human colonization of Rapa Nui and thus on its ecology

HLA in anthropology: the enigma of Easter Island

In this article, we first present four significant cases where human leukocyte antigen (HLA) studies have been useful for the reconstruction of human peopling history on the worldwide scale; i.e., the spread of modern humans from East Africa, the colonization of East Asia along two geographic routes, the co-evolution of genes and languages in Africa, and the peopling of Europe through a main northward migration. These examples show that natural selection did not erase the genetic signatures of our past migrations in the HLA genetic diversity patterns observed today. In the second part, we summarize our studies on Easter Island. Using genomic HLA typing, we could trace an introduction of HLA alleles of native American (Amerindian) origin to Easter Island before the Peruvian slave trades; i.e., before the 1860s, and provide suggestive evidence that they may have already been introduced in prehistoric time. Our results give further support to an initial Polynesian population of the island, but also reveal an early contribution by Amerindians. Together, our data illustrate the usefulness of typing for HLA alleles to complement genetic analyses in anthropological investigations