1-Alkyl-2, 3-Diacylglycerol Synthesis in Primary Culture Cells of Guinea Pig Harderian Gland

Abstract

Using a primary culture system of guinea pig Harderian gland cells, we investigated the metabolism of a unique lipid: 1-alkyl-2, 3-diacylglycerol containing methyl-branched fatty acids. The cells were obtained by collagenase digestion, and cells with lipid-droplets were collected by two-step centrifugation. We cultured these cells, and examined their lipid and fatty acid compositions. The de novo synthesis of lipids in these cells was studied as to the incorporation of [1 (2)-¹⁴C] acetate and [U-¹⁴C]glucose. The major lipid proved to be 1-alkyl-2, 3-diacylglycerol, as in tissue, and it contained a large amount of methylbranched fatty acids specific to this gland. The incorporation of [¹⁴C] acetate and [¹⁴C] glucose into 1-alkyl-2, 3-diacylglycerol in the cultured cells amounted to 79.7 and 88.2% of the total incorporation into the lipid fraction, respectively. The incorporation of [¹⁴C] acetate into fatty acids in the cultured cells was detected for the chain lengths of C 14 to C 25. The activities of glycerol-3-phosphate dehydrogenase in the cultured cells and Harderian gland were lower than that in adipose tissue. These results confirm that cultured cells reflect the lipid metabolism originating in the Harderian gland and show that this culture system can serve as one part of the armamentarium for further study of this unique lipid metabolism.