Phospholipids Of Thyroid-Gland

Total phospholipids in the thyroid of human females: 214 ± 27.8 μ g lipid phosphorus per g fresh weight were found higher than those in males: 142 ± 12 μ g lipid phosphorus per g fresh weight (mean ± S.E.). The corresponding values in pig thyroid were 333 ± 24.5 for females and 136 ± 12 for males. Thyroid phospholipids have been identified and determined by two-dimensional thin-layer chromatography. Percentage distribution of phospholipids is similar for the thyroids of both sexes and species and does not differ from those of other mammalian organs. Plasmalogens have been identified in the phosphatidyl ethanolamine fraction of normal human and pig thyroid. The mean ratio of C 16:0 dimethyl acetal (DMA)/C 16:0 for this fraction was 0.51 for 4 human males and 0.24 for 4 human females. The above ratio was higher for pig thyroids. Attempts to determine plasmalogens in the PE fractions of surgical thyroid specimens from a patient with cold nodules have indicated that these lipids were almost absent from the nodules, while paranodular tissue had increased ratio of C 16:0 DMA/C 16:0 as compared to normal thyroids of the same sex. All cold nodules of human thyroids contain a phospholipid tentatively identified as lysophosphatidyl ethanolamine accounted for 5 to 10 per cent of total phospholipids. The high content of a lysophospholipid in an abnormal human tissue is discussed in relation to the development of the disease. The composition of acyl-bound fatty acids is similar to that found in other mammalian organs and does not comprise nervonic acid.