Secretory activity of isolated thyroid adenomas

Area of Science:

• Endocrinology
• Molecular Biology
• Cell Biology

Background:

• Thyroid hormone synthesis and secretion involve complex processes, including thyroglobulin (Tg) uptake and hydrolysis.
• Thyroid adenomas are common endocrine neoplasms that can affect thyroid function.

Purpose of the Study:

• To investigate the catabolic phase of thyroid secretion in various types of thyroid adenomas.
• To compare the in vitro Tg processing in adenomas with normal thyroid tissue.

Main Methods:

• Incubation of thyroid slices with labeled thyroglobulin (Tg) in vitro.
• Examination of 22 thyroid adenoma specimens (cold, hot, toxic, pretreated) and 11 normal thyroid tissues.
• Assay of Tg pinocytosis, hydrolysis, and enzymatic activity of acid hydrolases.

Main Results:

• Tg pinocytosis was significantly impaired in all non-toxic adenomas (cold or hot).
• Toxic adenomas demonstrated activated catabolic hormonogenesis, including high pinocytosis, increased Tg hydrolysis, and hormone release.
• Pretreated toxic adenomas showed a slowed-down catabolic process.
• Elevated enzymatic activity of beta-galactosidase and cathepsin was observed in all investigated nodules, especially in toxic adenomas.

Conclusions:

• Non-toxic thyroid adenomas exhibit impaired thyroglobulin processing, affecting hormone secretion.
• Toxic adenomas display an activated catabolic pathway for hormone production, with pre-treatment modulating this activity.
• Lysosomal enzyme activity is generally increased in thyroid nodules, particularly in toxic adenomas.