Identification of main lipid components of mole rat Harderian gland

The Harderian gland of the mole rat has been demonstrated to have appeasement qualities on conspecifics. In this study total lipid content of the Harderian gland of the mole rat was evaluated and analyzed by means of thin-layer chromatography (TLC), densitometry, gas chromatography-mass spectrometry (GC-MS), FAB-MS, and NMR. More than 50% of the gland's fresh weight is composed of lipids, making it the highest Harderian gland lipid content ever found in rodents. Male and female lipid components differ considerably. Both have wax esters as the main lipid component, but in females the alcohol components were usually chains of 12 carbons, while in males they were mostly chains of 16 carbons. In addition, while in females the fatty acid residues were usually saturated, in males there was a double bond in the middle of the chain. As many as 25 different esters were found in females, and only seven in males. However, in the male an unusual volatile compound identified as 1-(3')-hexenyl-benzene was found. This sexual dimorphism may show that the gland function is sex-specific, and gives support to our earlier reports that the mole rat Harderian gland may be a source of pheromones.