Background and aimThe induction of thermogenic genes in white adipose tissue (WAT) of exercise‐trained rodents is commonly seen in animals housed at standard temperatures (e.g. ~20°C) despite not being seen in exercise‐trained humans1,2. Here, we hypothesised that raising and exercise training rodents at thermoneutrality (e.g. ~28°C) thus mimicking human physiology would negate the induction of thermogenic genes typically seen at standard housing temperatures.MethodsTwelve weanling (i.e. 3 weeks old) Sprague‐Dawley male rats were housed at thermoneutrality (28°C) and fed a high‐fat diet (HFD) to induce weight gain with (Ex) or without (C) exercise training. At 12 weeks of age Ex was commenced by swim‐training (i.e. 1 hour/day, 5 days per week) for 4 weeks. Metabolic assessment was undertaken in metabolic cages during the last 48h to assess energy intake, expenditure and physical activity in addition to the acute response to administration of a β3‐agonist (Mirabegron, 0.75mg/kg/d). Then, at 16 weeks of age following an overnight fast, tissues were taken for analysis of thermogenic genes and quantitative proteomics.ResultsEx attenuated weight gain, but did not affect food intake, energy expenditure, final body weight, fat mass, plasma insulin or glucose or HOMA‐IR. There was also no increase in energy expenditure in response to administration of Mirabegron with UCP1 mRNA in IWAT remaining undetectable in EX despite an upregulation of genes considered to be classical ‘browning’ inducers i.e. PGC1a, ADRB3 and DIO2. We found 189 proteins were differentially regulated in IWAT following exercise. Among the most significant were those regulating nuclear factor kappa B signalling (LRRFIP2), the mitochondrial electron transport chain (NDUFS6) and oxidative stress (SOD3). Gene ontology analysis demonstrated these enriched 51 groups based on their biological process including ‘regulation of alternative mRNA splicing, via spliceosome’, ‘DNA damage checkpoint’ and ‘regulation of type 2 immune response’ whilst only 13 groups were enriched based on their molecular function including ‘metallodipeptidase activity’, ‘ATPase regulator activity’ and ‘pre‐mRNA binding’.ConclusionUnlike at standard housing temperatures, exercise induced ‘browning’ of IWAT was absent in animals raised at thermoneutrality corroborating human data. Proteomic analysis further highlights alternate novel pathways in adipose tissue regulated by exercise training that could have functional relevance.Support or Funding InformationBritish Heart Foundation [grant number FS/15/4/31184/]This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.