Possible Interaction: Leucine and Triiodothyronine

“Lysine appearance did not change during fasting or T3 supplementation, but leucine appearance decreased with T3 supplementation during fasting.”

“The uptake of leucine , mediated by the amino acid transport system L, was inhibited by T3 and T4, and the nature of inhibition was competitive.”

“Urinary excretion of 3‐methylhistidine and plasma concentrations of valine, methionine, lysine, tyrosine, phenylalanine, isoleucine, leucine , and total essential and branched chain amino acids increased following administration of T3 , probably in part reflecting accelerated muscle proteolysis.”

“Moreover, the concentrations of Leu , Phe, and Arg were higher in T2 and T3 (P < 0.05).”

“Conversely, L-T3 inhibited the transport of [3H]leucine by pituitary cells (IC50 = 2 microM), but D-T3 and 3,5,3'-triiodothyroacetic acid (Triac) did not.”

“In this paper we have shown that T3 stimulates leucine uptake and incorporation into protein in primary cell cultures of neurons.”

“The relative increase of T3 levels from comfortable to cold or hot environmental temperatures, was significantly higher in L and D animals (30 vs 12%, respectively).”

“After 6 to 48 hours, triiodothyronine induced a marked reduction in leucine uptake into the proteins of the gills, intestine, kidney, and tail.”

“ T3 (10 μM) did not significantly trans stimulate L-[3H]phenylalanine efflux, but did competitively inhibit the trans stimulatory effect of 10 μM leucine.”

“Uptake of leucine , tyrosine, and tryptophan (10 M) was inhibited by the different iodothyronines (10 M), in particular T3.”