De novo fatty acid synthesis and NADPH generation in equine adipose and liver tissue

The lipogenic capacities of equine liver and adipose tissue explants were investigated in vitro. Preference for glucose or acetate as the primary carbon source for de novo fatty acid synthesis was determined using 14C labeled substrates. Additional aims included determining the relative contribution of NADPH generating pathways to reducing equivalent generation and comparing the lipogenic activity of two adipose depots, mesenteric and subcutaneous harvested from the crest region of the neck. Mesenteric adipose tissue had greater lipogenic activity than subcutaneous adipose tissue, and liver tissue showed minimal 14C incorporation into fatty acids, indicating a low hepatic lipogenic capacity. Acetate was found to be the primary carbon source for fatty acid synthesis due to both the appearance of the 14C label in the lipid fraction and the low activity of ATP-citrate lyase. Finally, the pentose phosphate and isocitrate dehydrogenase enzymes contributed to NADPH production in equine adipose tissue.