Influence of lipoprotein-lipase activity on plasma triacylglycerol concentration and lipid storage in three genotypes of ducks
Résumé
The lipoprotein-lipase (LPL) hydrolyses the triacylglycerols (TG) secreted by the liver and, thus, allows the storage of lipids onto the extrahepatic tissues. The LPL activity has been studied by injection of LPL antibodies in three genotypes of ducks (Muscovy (Cairina moschat), Pekin (Anas plathyrhynchos) and Mule (hybrids of male Muscovy ducks and female Pekin ducks)) under overfeeding condition. The results show a similar weight gain between injected and control animals. A higher liver steatosis is observed in Mule ducks (616 ± 18 g; 8.79% of body mass (BW)) and Muscovy ducks (514 ± 13 g; 7.05% BW) compared to Pekin ducks (353 ± 21 g; 5.89% BW, p b 0.05). Pekin ducks showed a much marked extrahepatic fattening of abdominal and subcutaneous adipose tissues. The LPL activity was evaluated by comparing the evolution of the plasma TG concentrations after injections of saline (control animals) or injections of specific LPL-antibodies. Inhibition of LPL activity performed by intravenous injections of LPL-antibodies showed a spectacular increase in the plasma TG concentrations in the three genotypes. That increase was considerably higher in Pekin ducks (98 ± 10 g/L) compared to Muscovy ducks (35 ± 2 g/L, p b 0.01) and Mule ducks (30 ± 4 g/L, p b 0.01). Those data suggest that a high export of lipids synthesized in liver and a high LPL activity occur in overfed Pekin ducks, which can favour the extrahepatic fattening to the detriment of the liver steatosis, and conversely in overfed Muscovy and Mule ducks. Full Latin names of the species used: Pekin ducks (Anas plathyrhynchos); Muscovy ducks (Cairina moschat); Mule ducks are hybrids of male Muscovy ducks and female Pekin ducks