Metabolic signatures in overwintering raccoon dogs (Nyctereutes procyonoides) (1101.13)

Abstract

The raccoon dog (RD) is a Eurasian dog‐like mammal with a peculiar wintering strategy. It is the only member of the family canidae that can spend cold winters in an inactive state. Our objective was to investigate the molecular signatures regulating energy homeostasis during the crucial phases of seasonal adaptation in RD (autumnal fattening and winter fasting). We analyzed several key regulators of metabolism /food intake on the transcription levels from RD hypothalamus (orexigenic: NPY, orexin‐2 receptors (OX2R) and anorexigenic: POMC, leptin receptors (LepR)) and from the RD plasma (leptin, insulin, ghrelin, peptide YY, GIP, interleukin 8, MCP‐1). The 10‐week winter fasting period had no significant effect on the analyzed mRNA expression levels in the hypothalamus. Plasma peptides and cytokines were also not significantly different. In contrast, autumnal fattening decreased the expression of hypothalamic OX2R (p=0,002) and also LepR (p=0,006). Plasma leptin was increased in the autumnal fattening phase (p=0,027). In conclusion, our results indicate that RD is well adapted to long periods of fasting. In autumnal fattening we observed a seasonal downregulation of hypothalamic OX2R and LepR in contrast to the increased leptin plasma levels. These lower levels of LepR during the autumnal fattening phase enable the animals to increase their food intake in spite of the inhibitory action of the circulating leptin. Grant Funding Source: Supported in part by the Academy of Finland