Sole-Navais, P. | Search bioRxiv

bioRxiv2021

The orexigenic force of olfactory palatable food cues in sated rats

BackgroundEnvironmental cues recalling palatable foods are ubiquitous and motivate eating beyond metabolic need, yet the timing of this response and whether it can develop towards a non-palatable readily available food remain elusive. Although there is increasing evidence indicating that external stimuli in the olfactory modality can communicate with the major hub in the feeding neurocircuitry, the hypothalamic arcuate nucleus (Arc), the identity of hypothalamic substrates has been only partially uncovered. MethodsUsing a palatable home-cage hidden-food paradigm, we investigate the ability of olfactory food cues to promote chow overconsumption in sated male rats, together with their impact on meal pattern. We likewise explore, by means of an immediate early gene marker, the neural mechanisms involved, including the possible engagement of the orexigenic ghrelin system. ResultsOlfactory detection of a familiar palatable food shifts diurnal patterns towards an increase in meal frequency to cause persistent overconsumption of chow in sated conditions. In line with the orexigenic response observed, sensing the palatable food in the environment stimulates food-seeking and risk-taking behavior, and also triggers release of active ghrelin. Olfactory food cues recruit intermingled populations of cells embedded within the feeding circuitry within the Arc, including, notably, those containing the ghrelin receptor, even when food is not available for consumption. ConclusionsThese data demonstrate leverage of ubiquitous food cues, not only for palatable food-searching, but also to powerfully drive food consumption in ways that resonate with heightened hunger, for which the orexigenic ghrelin system is implicated.

neuroscience↗

bioRxiv2020

Haplotype-based heritability estimations reveal gestational duration as a maternal trait and fetal size measurements at birth as fetal traits in human pregnancy

AbstractGenotype-based approaches for the estimation of SNP-based narrow-sense heritability [Formula] have limited utility in pregnancy-related outcomes due to confounding by the shared alleles between mother and child. Here, we propose a haplotype-based approach to estimate the genetic variance attributable to three haplotypes - maternal transmitted [Formula], maternal non-transmitted [Formula] and paternal transmitted [Formula] in mother-child pairs. We show through extensive simulations that our haplotype-based approach outperforms the conventional and contemporary approaches for resolving the contribution of maternal and fetal effects, particularly when m1 and p1 have different effects in the offspring. We apply this approach to estimate the explicit and relative maternal-fetal genetic contribution to the phenotypic variance of gestational duration and gestational duration adjusted fetal size measurements at birth in 10,375 mother-child pairs. The results reveal that variance of gestational duration is mainly attributable to m1 and m2 ([Formula]= 17.3%, S. E. = 5.2%; [Formula] = 12.2%, S. E. = 5.2%; [Formula] = 0.0%, S. E. = 5.0%). In contrast, variance of fetal size measurements at birth are mainly attributable to m1 and p1 ([Formula] = 18.6 - 36.4%, [Formula] = 0.0 - 5.2% and [Formula] = 4.4 - 13.6%). Our results suggest that gestational duration and fetal size measurements are primarily genetically determined by the maternal and fetal genomes, respectively. In addition, a greater contribution of m1 as compared to m2 and p1 [Formula] to birth length and head circumference suggests a substantial influence of correlated maternal-fetal genetic effects on these traits. Our newly developed approach provides a direct and robust alternative for resolving explicit maternal and fetal genetic contributions to the phenotypic variance of pregnancy-related outcomes.

genetics↗