[Is brown adipose tissue a store of long chain polyunsaturated fatty acids during postnatal developing brain?].

Mammals along their early postnatal period develop a substantial amount of a very active brown adipose tissue (BAT). Through this work we explored the possibility that BAT may function as a long chain polyunsaturated fatty acids reservoir (LC-PUFA) during the rapid growth of brain structures. In new born rats 1, 6, 12 and 20 days old, we analyzed fatty acid percentage of triglycerides (TG) and phospholipid fractions, and the absolute amount of TG. In 6 day old rats we also evaluated the extend of further desaturation of 1-14C linoleic acid administered by intraperitoneal injection. Results demonstrated a drastic increase of TG concentration during experimental period (1,5; 40; 118; 120 mg/g wet weight) and LC-PUFA percentage was higher in "1 and 6" than "12 and 20" days old rats (16-17% vs 5%). Our results showed that BAT stored important amounts of LC-PUFA. On the other hand, 1-14C linoleic acid incorporation was higher in liver than BAT. In contrast, the desaturated products of 1-14C linoleic acid /1-14C linoleic acid ratio was greater in BAT than liver (>4). This could indicate that BAT synthesizes LC-PUFA in addition to store it. In summary we demonstrated than BAT is an important reservoir of LC-PUFA during postnatal brain growth.