Acute exercise‐induced lipolysis and increase in levels of fatty acid esters of hydroxy fatty acids in adipose tissue are impaired in obese and aged mice

Improving adipose tissue (AT) metabolism through exercise might increase production of lipokines from the fatty acid esters of hydroxy fatty acids (FAHFA) family. Although exercise training can increase insulin sensitivity and levels of specific FAHFA in AT and the circulation in humans, the effects of acute exercise on FAHFA levels remain unclear. Previously untrained lean, obese and aged male C57BL/6J mice were subjected to acute treadmill exercise. AT lipolysis, metabolomic profile and FAHFA levels were analysed at baseline and 0 and 3 h postexercise. Baseline AT levels of FAHFA, particularly those containing mono- and polyunsaturated fatty acids, were lower in obese and aged mice compared with lean mice. AT-specific expression of genes related to de novo lipogenesis and lipolysis was reduced, particularly in obese mice, whereas expression of FAHFA hydrolysis-related genes was higher in aged mice. In lean mice, acute exercise increased plasma non-esterified fatty acids and their release from AT explants, which was suppressed in obese and aged counterparts. Only in lean animals, acute exercise led to a time-dependent increase in total FAHFA levels in AT, with the most pronounced increase observed in 13/12-regioisomers from different FAHFA subfamilies. The effect of acute exercise on AT FAHFA levels was stronger than that of fasting alone, revealing palmitoleic acid-containing FAHFA as the most differentiating regioisomers. In contrast, plasma FAHFA levels were minimally affected in all groups. In conclusion, acute exercise increases FAHFA levels in AT but not in plasma, and this effect appears to be negatively affected by obesity and ageing.