Consumption of out-of-season orange modulates fat accumulation, morphology and gene expression in the adipose tissue of Fischer 344 rats

Albert Gibert-Ramos,Anna Crescenti,M Josepa Salvadó,Hector Palacios-Jordan

doi:10.1007/s00394-019-01930-9

Abstract

PurposeAccording to the xenohormesis theory, animals receive signals from plants that give clues about the changing environment, and thus, depending on the season of the year, animals develop physiological changes to adapt in advance to the seasonal changes. Our objective was to study how the same fruit cultivated during two different seasons could affect the adipose tissue of rats.MethodsThirty-six Fischer 344 rats were acclimated for 4 weeks to long-day or short-day (SD) photoperiods. After adaptation, three groups (n = 6) from each photoperiod were supplemented either with orange from the northern (ON) or southern (OS) hemispheres harvested in the same month or a vehicle (VH) for 10 weeks. Biometric measurements, postprandial plasmatic parameters, gene expression of the inguinal white adipose tissue (IWAT) and brown adipose tissue (BAT), and the histology of the IWAT were analysed.ResultsThe OSSD group increased its fat content compared to the VHSD, while the ON groups showed no biometric differences. The OS groups were further studied, and the IWAT showed increased levels of Pparγ gene expression and a higher percentage of larger adipocytes compared to the VH group. The BAT showed down-regulation of Lpl, Cpt1b and Pparα in the OSSD group compared to that in the VHSD group, suggesting an inhibition of BAT activity, however, Ucp1 gene expression was up-regulated.ConclusionsWe observed a different effect from both fruits, with the OS promoting a phenotype prone to fat accumulation when consumed in an SD photoperiod, which might be explained by the xenohormesis theory.

Highlights

The xenohormesis theory posits that plants synthesise small molecules or secondary metabolites when under a mild stress and that these molecules are detected by heterotrophs when ingested, activating a response that allows them to adapt to this new environment to survive [1, 2]
We observed a similar effect on the adiposity index, Due to the effect of or southern (OS) consumption on fat weight in the SD photoperiod, we analysed the expression of several genes related to brown adipose tissue (BAT) activity in this photoperiod
Data are presented as the mean ± SEM and the four groups were compared by one-way ANOVA (p < 0.05) followed by Duncan’s new multiple range (MRT) post hoc test

Summary

Introduction

The xenohormesis theory posits that plants synthesise small molecules or secondary metabolites when under a mild stress and that these molecules are detected by heterotrophs when ingested, activating a response that allows them to adapt to this new environment to survive [1, 2]. This can be activating energy accumulation when food is scarce or triggering reproductive changes during good weather [3, 4]. Even though an excess of energy intake is marked as the principal contributor to an increase in fat accumulation in obesity, some authors disagree as to whether this is the main driver in obesity and whether other environmental factors such as climate, artificial light and day length could be involved [17, 18]

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