Antagonistic effects of chronic low frequency stimulation and thyroid hormone on myosin expression in rat fast-twitch muscle.
Antagonistic effects of chronic low frequency stimulation and thyroid hormone on myosin expression in rat fast-twitch muscle.
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DOI：
10.1016/s0021-9258(18)77444-9
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发表时间：
1990-08
期刊：
影响因子：
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通讯作者：
B. Kirschbaum;H. Kucher;A. Termin;A. Kelly;D. Pette
中科院分区：
文献类型：
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作者：
B. Kirschbaum;H. Kucher;A. Termin;A. Kelly;D. Pette
本研究探讨慢性低频刺激（CLFS）对甲状腺功能减退、甲状腺功能正常和甲状腺功能亢进大鼠快收缩肌中肌球蛋白重链（MHC）和轻链（MLC）表达的影响。在mRNA和蛋白水平的变化表明甲状腺激素和CLFS的拮抗作用：在甲状腺功能正常的条件下，CLFS主要引起MHCIIb-MCHIId-MHCIIa转换。虽然CLFS在甲状腺功能正常状态下不会诱导缓慢的MHCI，但这种亚型在甲状腺功能减退状态下存在，并且在CLFS下进一步增强，表明甲状腺激素的抑制作用强于CLFS的诱导作用。甲状腺功能亢进单独抑制MHCIIa的表达，并增强MHCIId到MHCIIb的转换。这种向更快的MHC同种型的转变仅被CLFS部分抵消。因此，似乎甲状腺激素对MHC亚型的表达具有分级抑制作用，顺序为MHCIId小于MHCIIa小于MHCI。升高的神经肌肉活动部分抵消了这些激素的作用。MLC mRNA的变化与MHC模式的变化一致，即MHCIIb的增加或减少导致MLC 3f表达的相应变化。慢MHCI和慢MLC亚型存在类似的关系。
This study investigates effects of chronic low frequency stimulation (CLFS) on myosin heavy (MHC) and light chain (MLC) expression in fast-twitch muscles in hypothyroid, euthyroid, and hyperthyroid rats. The changes at both the mRNA and protein level indicated antagonistic effects of thyroid hormone and CLFS: under euthyroid conditions, CLFS mainly elicited a MHCIIb—-MCHIId—-MHCIIa transition. Whereas CLFS did not induce the slow MHCI in the euthyroid state, this isoform was present in the hypothyroid state and was further enhanced with CLFS indicating the suppressive effect of thyroid hormone to be stronger than the inductive influence of CLFS. Hyperthyroidism alone suppressed the expression MHCIIa and enhanced a MHCIId to MHCIIb transition. This shift to the faster MHC isoforms was only partially counteracted by CLFS. Thus, it appeared that thyroid hormone had a graded suppressive effect on the expression of MHC isoforms in the order MHCIId less than MHCIIa less than MHCI. Elevated neuromuscular activity partially counteracted these hormone effects. Changes in MLC mRNAs were consistent with those in the MHC pattern, i.e. increases or decreases in MHCIIb led to corresponding changes in the expression of MLC3f. A similar relationship existed for the slow MHCI and the slow MLC isoforms.