Homeostatic non-shivering thermogenesis in humans facts and hypotheses

This review considers current research of different forms of non-shivering thermogenesis related to thermoregulatory and substrate homeostasis. The term “homeostatic non-shivering thermogenesis (HNST)” is proposed for explanation of facultative heat production stimulated by exposure to cold, food intake and accumulation of lactate during intensive muscle loading. Similarities and differences in physiological activity are displayed in three HNST types. Existence of a number of common points makes it possible to propose common physiological mechanisms of HNST realization. Among other candidates for HNST location, the brown adipose tissue (BAT) fits best as its function is specifi between thermogenic function in cold environment and diet-induced thermogenesis that makes it possible to link these two HNST types with BAT activity. Here we present the data indirectly confirming BAT functioning in processes of homeostatic normalization not related to cold acclimation or food intake. We also consider new data about BAT functional activity, its topographic body location, mechanisms of uncoupled respiration in different tissues in adult humans and about methods of BAT diagnostics which include the use of molecular markers. We list a number of facts confirming our suggestion about BAT activity being related to homeostatic normalization after physical loading. In conclusion, we propose an experimental research program for the testing of our hypothesis regarding BAT universal homeostatic function in humans.