ABSTRACT
The present study demonstrates that exposure of human thyroid slices obtained during planned surgery of patients with Graves' disease to thyrotropin stimulates the phospholipid metabolism as measured by an increase incorporation of 2-myo-[3H]-inositol into phosphatidylinositol and poliphosphatidylinositides and the generation of InsP3. The results indicate that adenosine, probably via the A1 type of P1 receptor, modulates these actions, both incorporation of labelled substrate into thyroid slices as well as its metabolism to active compounds which could play a role in a cell signalling system. These observations indicate the significance of the phosphatidilinositol pathway in signal transmission of both, thyrotropin as well as P1 purinergic receptors agonists in human thyroid.
Subject(s)
Adenosine/pharmacology , Graves Disease/metabolism , Phosphatidylinositols/metabolism , Thyroid Gland/drug effects , Thyrotropin/pharmacology , Adolescent , Female , Humans , Middle Aged , Thyroid Gland/metabolism , Thyroid Gland/physiopathologyABSTRACT
The present study demonstrates that exposure of human thyroid slices to thyrotropin causes an increase in phospholipid metabolism as measured by an increased incorporation of myo-2-[3H]-inositol into phosphatidylinositol, the generation of InsP3 and formation of GInsP as well as metabolism of phosphatidylcholine and phosphatidic acid. These results indicate that adenosine, probably via the A1 type of P1 receptor, modulates both incorporation of labelled substrate into thyroid slices and its metabolism to active compounds which could play a role in a cell signalling system. These observations confirmed suggestions about the physiological role of the phosphatidylinositol pathway in signalling action of thyrotropin and purinergic receptors in human thyroid.
Subject(s)
Phosphatidylinositols/metabolism , Thyroid Gland/physiology , Thyrotropin/pharmacology , Adenosine/pharmacology , Adult , Female , Goiter/metabolism , Humans , In Vitro Techniques , Inositol/metabolism , Inositol Phosphates/metabolism , Receptors, Purinergic/metabolism , Signal TransductionABSTRACT
Differences particular in phospholipid levels from pig thyroid membranes incubated in the presence of TSH were observed, but with exception of lysophosphatidylcholine, were not statistically significant. TSH evoked about a twice increase of lysophosphatidylcholine content. A slight decrease of phosphatidylcholine, phosphatidylinositol and phosphatidylserine were found, when at the same time a slight increase of phosphatidylethanolamine and sphingomyelin level was noted. There were no statistical differences in range fluctuation of individual phospholipid levels, but direction of fluctuation (i.e. decrease or increase) were identical for every single phospholipid in all experiments. An increase of lysophosphatidylcholine and a simultaneously decrease of phosphatidylcholine contents suggests the stimulation of phospholipase A2 activity.
Subject(s)
Phospholipids/analysis , Thyroid Gland/drug effects , Thyroid Gland/ultrastructure , Thyrotropin/pharmacology , Animals , Cell Membrane/chemistry , Cell Membrane/drug effects , Kinetics , Lysophosphatidylcholines/metabolism , Phosphatidylcholines/metabolism , Swine , Thyroid Gland/metabolismABSTRACT
The phospholipids from human thyroid have been identified and determined by two-dimensional chromatography. The total amount of lipid phosphorus was higher in pathological thyroids (especially in thyroid with Graves' disease) as compared to postmortem tissue. Insignificant differences in percentage distribution of phospholipids between normal tissue and from patients with Graves' disease and nodular goiter were noted. An increase of phosphatidylcholine and a decrease of phosphatidylinositol and sphingomyelin in pathological thyroids were observed. Physiological role of phospholipids in thyroid gland is discussed.
