English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Type II deiodinase (D2) plays a key role in regulating thyroid hormone-dependent processes in, among others, the central nervous system (CNS) by accelerating the intracellular conversion of T4 into active T3. Just like the well-known daily rhythm of the hormones of the hypothalamo-pituitary-thyroid axis, D2 activity also appears to show daily variations. However, the mechanisms involved in generating these daily variations, especially in the CNS, are not known. Therefore, we decided to investigate the role the master biological clock, located in the hypothalamus, plays with respect to D2 activity in the rat CNS as well as the role of one of its main hormonal outputs, i.e. plasma corticosterone. D2 activity showed a significant daily rhythm in the pineal and pituitary gland as well as hypothalamic and cortical brain tissue, albeit with a different timing of its acrophase in the different tissues. Ablation of the biological clock abolished the daily variations of D2 activity in all four tissues studied. The main effect of the knockout of the suprachiasmatic nuclei (SCN) was a reduction of nocturnal peak levels in D2 activity. Moreover, contrary to previous observations in SCN-intact animals, in SCN-lesioned animals, the decreased levels of D2 activity are accompanied by decreased plasma levels of the thyroid hormones, suggesting that the SCN separately stimulates D2 activity as well as the hypothalamo-pituitary-thyroid axis.

Daily Variations in Type II Iodothyronine Deiodinase Activity in the Rat Brain as Controlled by the Biological Clock