Hamster costovertebral organ lipogenesis in vitro and in vivo: effects of cerulenin.

An assay for lipid synthesis by hamster costovertebral organ (CVO) in vivo is described. When sodium [1-14C]acetate is injected intraperitoneally into male hamsters, maximum labeling of CVO lipids occurs after 5 min and remains constant for more than 40 min following injection. The major products of in vivo labeling are polar lipids, triglycerides, and sterols. The distribution of radiolabeled lipid products in vivo is similar to that obtained from incubation of CVO punch biopsy specimens with [1-14C]acetate in vitro. Castration results in an greater than 80% inhibition of CVO lipid synthesis as measured using in vitro or in vivo techniques. Cerulenin inhibited de novo fatty acid synthesis by the 100,000 X g supernatant of a CVO homogenate and the incorporation of [1-14C]acetate into fatty acids by CVO biopsies in vitro. Topical application of cerulenin to the CVO did not inhibit synthesis of radiolabelled lipids from [1-14C]acetate in vivo. The in vivo assay provides a necessary means of determining the physiological significance of in vitro results obtained when assaying for inhibitors of sebaceous gland lipogenesis.