Differentiationin vitroof omental and subcutaneous pre-adipocytes from Spanish Lacha and Rasa Aragonesa sheep

Abstract

AbstractFactors responsible for breed- and depot-specific differences in the development of lipogenic enzymes, and hence lipogenic capacity of adipocytes, in sheep adipose tissue have been investigated using a serum-free cell culture system. Effects of insulin, tri-iodothyronine and exogenous lipid on the development in vitro of the lipogenic enzymes glycerol 3-phosphate dehydrogenase (G3PDH), fatty acid synthetase (FAS), NADP-malate dehydrogenase (ME), glucose 6-phosphate dehydrogenase (G6PDH), and isocitrate dehydrogenase (ICDH) in omental and subcutaneous pre-adipocytes from Lacha and Rasa Aragonesa lambs were investigated. Addition of insulin plus tri-iodothyronine caused pre-adipocyte differentiation, which was enhanced by addition of a lipid supplement. G3PDH activities achieved by differentiation of pre-adipocytes in vitro were similar to those found in vivo; furthermore after differentiation in vitro adipocytes from Rasa Aragonesa lambs had a greater G3PDH activity than adipocytes from Lacha lambs, as found in vivo. In contrast activities of FAS, G6PDH and ME achieved by differentiation in vitro were much greater than those found previously in vivo. While breed- and depot-specific changes in G6PDH observed after differentiation in vitro were similar to those observed in vivo, changes in FAS induced in vitro differed from those found during development in vivo. The study shows that pre-adipocytes from Rasa Aragonesa and Lacha lambs have intrinsic depot- and breed-specific differences in their ability to differentiate and express lipogenic enzymes. The combination of insulin, tri-iodothyronine and a lipid supplement appears to be sufficient to account for in vivo G3PDH activities but other factors are required to explain activities of FAS, G6PDH and ME found in vivo.