PMID: 8594946Dec 1, 1995Paper

T4 depresses olfactory responses to L-alanine and plasma T3 and T3 production in smoltifying Atlantic salmon

The American Journal of Physiology
P P MorinJ G Eales

Abstract

During natural or induced smoltification, Atlantic salmon exhibit spring elevations in olfactory activity and plasma L-thyroxine (T4). To determine whether T4 influences olfactory activity, we administered T4 to late parr in early April and measured olfactory bulb electroencephalogram and olfactory epithelium electroolfactorogram responses to L-alanine nasal stimulation, plasma T4 and 3,5,3'-triiodo-L-thyronine (T3) levels, and hepatic and brain monodeiodination. T4 treatment raised plasma T4 to 15 ng/ml, simulating the smolt T4 surge, and depressed plasma T3 and electroencephalogram responses, without modifying electroolfactorogram responses. Decreased plasma T3 may be explained by inhibition of hepatic T4 outer-ring deiodination, generating T3, and stimulation of inner-ring deiodination, degrading T4 and T3. Brain T4 outer-ring deiodination was also strongly inhibited. In conclusion, creation of a high plasma T4 concentration simulating the natural smolt peak depressed olfactory bulb responses to L-alanine due to the high T4 concentration or the depressed T3 availability in brain induced by T4. T4 may terminate the period of heightened olfactory responsiveness during smoltification.

Citations

Nov 27, 2020·Frontiers in Endocrinology·Cole K Deal, Helene Volkoff

❮ Previous
Next ❯

Related Concepts

Related Feeds

Basal Ganglia

Basal Ganglia are a group of subcortical nuclei in the brain associated with control of voluntary motor movements, procedural and habit learning, emotion, and cognition. Here is the latest research.