Related Experiment Video
Updated: May 5, 2026

Author Spotlight: In Vivo Assessment of Thyroid Hormone Disruption Using the THAI Mouse Model
Published on: October 6, 2023
Responses upon multiple administration of L-thyroxine in hens
H Majewska1, A M Konecka, A Witowski
1Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzebiec, Poland.
Abstract:
Studies on the influence of repeated injections of L-thyroxine on enzyme activity and total protein level in the blood plasma of White Rock and Sussex hens have shown that: 1. The total protein level in both races decreased significantly. 2. Activity of aldolase increased in White Rock hens while in Sussex hens it increased considerably only after the last injection. 3. Activity of alanine aminotransferase did not change in White Rock hens and increased in the blood plasma of Sussex hens. 4. In both races, the activity of aspartate aminotransferase increased initially and changed after L-thyroxine injection. 5. Activity of alkaline phosphatase increased in White Rock hens, while in Sussex hens it decreased. 6. Statistically significant differences between activities of examined enzymes in both races after L-thyroxine administration were found.
Related Concept Videos
Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The...
Hyperthyroidism I: Introduction
Functions of Thyroid Hormones
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Hyperthyroidism II: Pathophysiology
Hypothyroidism II: Pathophysiology
Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...

