Primary culture of adipoblasts from obese and lean Zucker rat adipose tissue.

Adipocyte precursors derived from the epididymal fat pads of young adult lean (FaFa) and obese (fafa) Zucker rats were established in primary culture. The two types of culture were used to assess intrinsic cellular differences in proliferative capacity, lipoprotein lipase (LPL) activity and triglyceride (TG) accumulation related to genotype. Proliferative capacity was similar over seven days in vitro in lean- and obese-derived cultures. Heparin-releasable LPL activity was significantly greater in lean- than in obese-derived cultures grown in media supplemented with penicillin and streptomycin (pen-strep). However, when grown in media supplemented with cephalothin, heparin-releasable and total LPL activity increased significantly in obese-derived cultures and equalled LPL activity in lean-derived cultures. Substantial LPL activity was measurable in both types of culture at confluence, before exposure to media that promoted lipid-filling. TG accumulation was significantly greater in lean-than in obese-derived cultures in the presence of pen-strep but was similar in both culture types grown in cephalothin. These data support our hypothesis that the fa gene may affect mechanisms of protein turnover regulation, since pen-strep, but not cephalothin, has inhibitory effects on mammalian protein synthesis and degradation. The substantial LPL activity present in confluent, but unconverted cultures, suggests that some percentage of cells in the confluent monolayers are adipoblasts.