Comparative analysis of naked mole-rat thermogenesis and its potential to maintain euthermia in response to cold

The naked mole-rat (NMR) is a subterranean rodent known for its unique thermal biology, exceptional longevity and resistance to cancer and hypoxia. However, its thermal biology remains controversial, with various reports describing NMRs as poikilotherms, heterotherms, mesotherms or partial homeotherms. Here, we investigated whether the thermogenic potential of NMR brown adipose tissue and its UCP1 differ from those in mice and whether the lack of thermal insulation causes extreme changes in NMR body temperature upon cold exposure. Through longitudinal molecular, thermal, metabolic, and behavioral measurements, we found that NMRs initiated non-shivering thermogenesis and elevated body temperature but could not sustain it due to excessive heat loss and limits to substrate availability. Our results suggest that NMRs represent a unique thermoregulatory category that doesnt fit neatly into traditional classifications. In vitro and in vivo experiments showed that the NMR UCP1 is functional and can be activated and inhibited as expected for most other mammals. We further demonstrated that artificial insulation can partially restore thermoregulatory capabilities in NMRs. This study employs an advanced methodology to characterize the thermal biology of NMRs and helps resolve a long-standing controversy in the field. Significance StatementThis study provides critical insights into the thermal biology of naked mole-rats (NMRs), resolving long-standing controversies regarding their thermoregulatory strategies. We highlight the unique adaptations and limitations of NMR physiology by demonstrating that NMRs possess functional non-shivering thermogenesis and UCP1 but fail to maintain homeothermy due to excessive heat loss. Our findings suggest that artificial insulation can partially restore their thermoregulatory capabilities, offering a new perspective on the evolutionary and ecological significance of fur loss in NMRs. This research advances our understanding of mammalian thermal biology and presents an updated model for NMRs, bridging gaps between previous conflicting reports.