Interactions between thyreostimulin and PAF-acether on thyroid cell metabolism.
1-O-Alkyl, 2-acetyl sn-glycerylphosphorylcholine (platelet activating factor (PAF)-acether) originally described as a platelet activating factor, is effective on various parameters in different cells. It seemed interesting to us to test it on porcine thyroid cells cultured for 1 to 5 days in the absence (control cells) or in the presence of 0.1 mU/ml thyreostimulin (TSH cells). At concentrations ranging from 0.5 to 2.5 microM, PAF-acether inhibited significantly the accumulation of cyclic AMP resulting from a 5 min incubation of the cells with TSH (40 mU/ml) or forskolin (0.1 mM). PAF-acether alone did not affect basal cyclic AMP accumulation. The maximal inhibition was obtained on a 3 day culture and amounted to 40-50%. The inhibition was transient and vanished after a 30 min incubation. The effects of PAF-acether (0.5 microM) on phospholipid metabolism depended closely upon the physiological state of the cells and upon the age of the culture. When PAF-acether was incubated for 2 h with [32P]phosphate, it mimicked the effects of TSH, i.e. it increased phosphatidylinositol (PI) labelling on 1 day control cells (expected effect) and decreased it with 1 day TSH cells (reverse effects). The PAF-acether effect was rapid in onset. After cell prelabelling for 2 h in the presence of TSH, PAF-acether added for 15 min completely counteracted the hormone effects on PI and phosphatidylcholine (PC) but increased the phosphatidic acid (PA) labelling. The effect of PAF- acether on PI labelling was partially antagonized by forskolin.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin; D000242:Cyclic AMP / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology; D007457:Iodine Radioisotopes; D010716:Phosphatidylinositols / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology*
D004224:Diterpenes; D007457:Iodine Radioisotopes; D010716:Phosphatidylinositols; D010743:Phospholipids; D010972:Platelet Activating Factor; D011506:Proteins; D005576:Colforsin; D013972:Thyrotropin; D000242:Cyclic AMP