Prasad C, Edwards R M
Endocrinology. 1984 Mar;114(3):941-5. doi: 10.1210/endo-114-3-941.
Synthesis of phosphatidylcholine (PC) by S-adenosylmethionine-dependent methylation of phosphatidylethanolamine has previously been associated with receptor-mediated histamine and pituitary hormone secretion. We investigated stimulation of phospholipid methylation by TSH and its possible role in thyroid hormone secretion. Rat hemithyroids were incubated in Krebs-Henseleit-glucose-BSA buffer and the effect of various treatments on the incorporation of [3H-methyl]L-methionine into PC and T4/T3 secretion was studied. TSH treatment elevated thyroid phosphatidylethanolamine methyltransferase activity, the incorporation of [3H-methyl]methionine into PC, and T4/T3 secretion. The increase in PC synthesis was linear up to 6 h in a dose-dependent fashion (half-maximal stimulation at 2.5 micrograms TSH/ml). Stimulation required protein synthesis, because cycloheximide inhibited the increase in PC synthesis by 77%. Inhibitors of phospholipid methylation (100 microM adenosine + 10 microM L-homocysteine thiolactone + 10 microM erythro-9[2-hydroxy-3-nonyl]adenine) significantly decreased TSH-stimulation of phospholipid methylation but not T3/T4 secretion. In conclusion, stimulation of thyroid phospholipid methylation by TSH is not required for stimulated secretion of thyroid hormones.
通过磷脂酰乙醇胺的S-腺苷甲硫氨酸依赖性甲基化合成磷脂酰胆碱（PC），此前已被认为与受体介导的组胺和垂体激素分泌有关。我们研究了促甲状腺激素（TSH）对磷脂甲基化的刺激作用及其在甲状腺激素分泌中的可能作用。将大鼠半甲状腺在Krebs-Henseleit-葡萄糖-牛血清白蛋白缓冲液中孵育，研究了各种处理对[3H-甲基]L-甲硫氨酸掺入PC以及T4/T3分泌的影响。TSH处理提高了甲状腺磷脂酰乙醇胺甲基转移酶活性、[3H-甲基]甲硫氨酸掺入PC的量以及T4/T3分泌。PC合成的增加在长达6小时内呈剂量依赖性线性增加（2.5微克TSH/毫升时达到半数最大刺激）。刺激需要蛋白质合成，因为放线菌酮将PC合成的增加抑制了77%。磷脂甲基化抑制剂（100微摩尔腺苷 + 10微摩尔L-同型半胱氨酸硫内酯 + 10微摩尔erythro-9[2-羟基-3-壬基]腺嘌呤）显著降低了TSH对磷脂甲基化的刺激，但不影响T3/T4分泌。总之，TSH刺激甲状腺磷脂甲基化并非甲状腺激素刺激分泌所必需。
