Fig. 1.

Effects of n-3 PUFAs on sterol-regulatory element binding protein-1 (SREBP-1) abundance in primary hepatocytes. Primary hepatocytes were incubated overnight in Williams E medium + 20 mM lactate + 10 nM DEX with no insulin or serum. The next day, cells were treated with 10 nM insulin and 25 mM glucose in the absence and presence of n-3 PUFAs with BSA (fatty acid/BSA = 5). A: Primary hepatocytes were treated with and without varying concentrations of 22:6,n-3. Cells were harvested after 24 h for isolation of microsomal and nuclear proteins for the measurement of precursor SREBP-1 (pSREBP-1; solid line) and nuclear SREBP-1 (nSREBP-1; dashed line) by immunoblotting (see Materials and Methods). The antibody recognizes both SREBP-1a and SREBP-1c. Results are presented as percentage of control after treatment with fatty acids and are representative of two separate experiments. B: Cells were treated with or without 100 μM 20:5,n-3 or 22:6,n-3 for 24 h. Microsomal and nuclear protein was extracted for measurement of pSREBP-1 and nSREBP-1 by immunoblotting (see Materials and Methods). Veh, vehicle. C: Results of five separate experiments were quantified, presented as arbitrary density units (means ± SD), and evaluated using ANOVA plus post hoc Tukey’s honestly significant difference test (http://faculty.vassar.edu/lowry/VassarStats.html). * P < 0.05, vehicle versus 22:6,n-3. DEX, dexamethasone.