Daniel Kuti1,2, Zsuzsanna Winkler1, Agnes Polyak1, Szilamer Ferenczi1, Krisztina J. Kovacs1
1 Laboratory of Molecular Neuroendocrinology/Institute of Experimental Medicine Hungarian Academy of Sciences, Budapest
2 Károly Rácz School of Phd Studies, Neurosciences (“János Szentágothai”)/Semmelweis University, Budapest
Introduction: Brown adipose tissue (BAT) plays an essential role in thermoregulation. Cold ambient temperature activates BAT and induce thermogenesis via different molecular pathways using fatty acids and glucose as substrate. In contrast, thermogenesis is suppressed in warm temperature. BAT glucose uptake is stimulated by cold and insulin, however the relationship between thermoregulation and insulin sensitivity is not fully explored.
Aims: In this current study, we investigated the metabolic activity of brown adipose tissue at different ambient temperatures (4°C, 21°C, 30°C) and its relation to glycemic control.
Method: C57Bl6 male mice were acclimatized at 4°C, when BAT is totally exposed to non-shivering thermogenesis; at 21°C room temperature and at 30°C thermoneutral condition for mice. After acclimatization, mice were fasted overnight and injected with insulin on the next day morning. Animals were decapitated after 1 hour of the insulin treatment, trunk blood was collected and interscapular brown adipose tissues were dissected for histology and RT-PCR measurements.
Results: Histological results revealed significant temperature-dependent morphological rearrangements in BAT. The characteristic lipid droplets were completely disappeared from the tissue of animals kept at 4°C. In contrast, at 30°C BAT contained large lipid droplets. Blood glucose level and rectal temperature positively correlated with temperature after insulin exposure, however, expression of insulin responsive glucose transporter (GLUT4) and the lipolytic enzyme (DGAT1) were negatively correlated with it in BAT. UCP1 and DIO2 genes were significantly downregulated at 30°C and upregulated at 4°C.
Discussion: These results highlight the significance of brown adipose tissue in the thermogenesis and glycemic control at different thermal conditions.
SUPPORTED BY THE ÚNKP-18-3-III-SE-35 NEW NATIONAL EXCELLENCE PROGRAM OF THE MINISTRY OF HUMAN CAPACITIES
Doctoral School: Neurosciences (“János Szentágothai”)
Supervisor: Krisztina J. Kovacs
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