Muscle and brown adipose tissue fatty acid profiles in cold-exposed rats.

Effects of cold acclimation and cold exposure for 25 generations on triglyceride (TG)-, total phospholipid (PL)-, and cardiolipin (CL)-fatty acid (FA) compositions were studied in the different types of skeletal muscles (red and white muscles from quadriceps, and soleus) as well as brown adipose tissue (BAT) in rats. TG: in cold-acclimated rats (CA) and rats reared in cold for 25 generations (25G) white muscle showed the decreased saturated FA (SA) and increased polyunsaturated FA (PU). In soleus of 25G, monounsaturated FA (MU) and PU increased, and SA decreased. In BAT, SA increased and MU decreased in CA, and SA and PU decreased, and MU increased in 25G. PL: in red muscle of CA, SA increased and PU decreased. In red muscle of 25G the similar but more marked changes were found accompanied by lowered arachidonic acid and unsaturation index (UI). In BAT, SA, PU, arachidonic acid, and UI increased in CA, and arachidonic acid increased in 25G. CL: in red and white muscles of 25G, oleic acid and MU increased. In BAT, arachidonic acid increased in CA and 25G, and UI increased in 25G. These results suggest that FA unsaturation of CL in the muscles as well as BAT is involved in an enhanced thermogenesis in cold-exposed rats.