The raccoon dog (Nyctereutes procyonoides) is a canid with autumnal fattening and passive wintering strategy.
We examined the effects of wintertime fasting and seasonality on AMP-activated protein kinase (AMPK), a regulator
of metabolism, and its target, acetyl-CoA carboxylase (ACC) on the species. Twelve farmed raccoon dogs
(eleven females/one male) were divided into two groups: half were fasted for ten weeks in December–March
(winter fasted) and the others were fed ad libitum (winter fed). A third group (autumn fed, eight females) was
fed ad libitum and sampled in December. Total AMPK, ACC and their phosphorylated forms (pAMPK, pACC)
were measured from hypothalamus, liver, intra-abdominal (iWAT) and subcutaneous white adipose tissues
(sWAT). The fasted animals lost 32% and the fed 20% of their body mass. Hypothalamic AMPK expression was
lower and pACC levels higher in the winter groups compared to the autumn fed group. Liver pAMPK was
lower in the winter fasted group, with consistently decreased ACC and pACC. AMPK and pAMPK were downregulated
in sWAT and iWAT of both winter groups, with a parallel decline in pACC in sWAT. The responses of
AMPK and ACC to fasting were dissimilar to the effects observed previously in non-seasonal mammals and hibernators.
Differences between the winter fed and autumn fed groups indicate that the functions of AMPK and ACC
could be regulated in a season-dependent manner. Furthermore, the distinctive effects of prolonged fasting and
seasonal adaptation on AMPK–ACC pathway could contribute to the wintering strategy of the raccoon dog