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Thyroid function and polyamines. II. Thyrotropin stimulation of polyamine biosynthesis in the rat thyroid
Endocrinologia Japonica
|August 1, 1975
Summary
Thyrotropin (TSH) and TSH-releasing hormone (TRH) stimulate thyroid growth by increasing polyamine biosynthesis. These hormones activate key enzymes, influencing thyroid enlargement and nucleic acid metabolism.
Area of Science:
- Endocrinology
- Molecular Biology
- Biochemistry
Background:
- Thyroid growth is regulated by hormones like thyrotropin (TSH).
- Polyamines are crucial for cell growth and nucleic acid metabolism.
- The role of polyamines in TSH-mediated thyroid growth requires further elucidation.
Purpose of the Study:
- To investigate the effect of TSH and TRH on polyamine metabolism in the rat thyroid.
- To determine the role of polyamines in TSH-induced thyroid growth and nucleic acid metabolism.
Main Methods:
- TSH and TRH were administered to rats.
- Activity of L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase was measured.
- Intracellular polyamine levels (putrescine, spermidine, spermine) and RNA/DNA ratios were analyzed.
Main Results:
- TSH and TRH significantly increased thyroid L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase activity.
- Methylthiouracil treatment led to increased enzyme activity and thyroid enlargement.
- Putrescine and spermidine levels rose during thyroid growth, while spermine remained constant.
- The RNA/DNA ratio correlated with the spermidine/spermine ratio.
Conclusions:
- TSH stimulates polyamine biosynthesis in the thyroid by upregulating decarboxylase activity.
- Polyamines likely play a significant role in regulating thyroid growth and nucleic acid metabolism.