The mechanism of thyrotrophin action in relation to lipid metabolism in thyroid tissue |
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| Authors: | T. W. Scott S. C. Mills N. Freinkel |
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| Affiliation: | Thorndike Memorial Laboratory and Second and Fourth (Harvard) Medical Services, Boston City Hospital and Department of Medicine, Harvard Medical School, Boston, Mass. 02118, U.S.A., and the Commonwealth Scientific and Industrial Research Organization, Division of Animal Physiology, The Ian Clunies Ross Animal Research Laboratory, Prospect, N.S.W., Australia, and the Department of Medicine, Northwestern University, Chicago, Ill. 60611, U.S.A. |
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| Abstract: | 1. The effects of thyrotrophin in vitro on the incorporation of [(14)C]-glucose, -glycerol, -palmitate and -oleate into the lipids of thyroid tissue were examined. 2. Thyrotrophin increased the incorporation of these (14)C-labelled precursors into phosphatidylinositol specifically. 3. Thyrotrophin also increased the proportion of (14)C radioactivity from labelled glucose, glycerol, palmitate and oleate incorporated into the 1,2-diglycerides. 4. The addition of thyrotrophin to thyroid slices for 10min., after 2hr. of prelabelling with [(14)C]glycerol, also increased the proportion of (14)C radioactivity incorporated into the 1,2-diglyceride fraction. 5. After incubation of thyroid tissue with [1-(14)C]palmitate, thyrotrophin caused a two- to three-fold increase in the specific radioactivity of palmitate isolated from phosphatidylinositol and 1,2-diglycerides. In contrast, the specific radioactivity of palmitate isolated from the choline and ethanolamine phosphoglycerides, 1,3-diglycerides and triglycerides was not increased by thyrotrophin. |
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