The stress of being alone: Removal from the colony, but not social subordination, increases fecal cortisol metabolite levels in eusocial naked mole-rats

Life expectancy, family constellation and stress in giant mole-rats ( Fukomys mechowii )

“…Our linear mixed models did not reveal an age effect, presumably because we corrected for several influential factors; however, our behavioural data indicate that stress levels of conventional non-breeders could increase with age (which is equivalent to an increase in family size), as long as these animals stay in the natal family and are involved in agonistic interactions with family members. Previous studies using naked mole-rats found that family disruption, isolation of individuals or both lead to increased cortisol secretion, measured in plasma [28] or faeces [29]. Another study found that urinary cortisol levels decreased in female F. damarensis non-breeders after separation from the natal family [34], a finding in line with the lower hair cortisol levels of orphaned non-breeders in the present study.…”

Characterization of brown adipose tissue thermogenesis in the naked mole-rat (Heterocephalus glaber), a heterothermic mammal

“…Previous reports on mice and rats have indicated that chronic social isolation affects the metabolism and volume of adipose tissues, including BAT 34 , 35 , and that psychological stresses, such as social defeat 3 , handling 4 , or the presence of an intruder 5 , have been shown to induce BAT thermogenesis. Recent studies have revealed that cortisol concentration is also upregulated in NMRs after social isolation 36 , 37 , suggesting that social isolation induces psychological stress in NMRs. Importantly, according to the previous studies 38 , 39 , we did not use lactating queens in the experiments of Fig.…”

Characterization of brown adipose tissue thermogenesis in the naked mole-rat (Heterocephalus glaber), a poikilothermic mammal

“…Previous reports in mice and rats have indicated that social isolation affects the metabolism and volume of adipose tissues, including BAT 29,30 , and that psychological stresses, such as social defeat 3 , handling, 4 or the presence of an intruder, 5 have been shown to induce BAT thermogenesis. Recent studies have revealed that cortisol concentration was also upregulated in NMRs after social isolation 31,32 , suggesting that social isolation induces psychological stress in NMRs. Although the differences in stress levels between the queen and other colony members and the neurological systems to transmit the stress to BAT during social isolation in NMRs are still unknown, such differences may contribute to the observed difference in BAT thermogenesis in the isolated situation.…”