ISTA13‐catecholamine toxicity and metabolism in the ciliated protozoan, Tetrahymena pyriformis

Abstract

A high throughput culture methodology of unicellular eukaryote Tetrahymena pyriformis, strain GL were used for the determination of catecholamines toxicity and their metabolism. Catecholamines exhibited acute toxicity to Tetrahymena cells where dopamine and L-DOPA showed higher toxic potential of EC(10) (0.39 and 0.63 mg/L, respectively) and EC(20) (1.1 and 1.0 mg/L, respectively). All the testing catecholamines were highly degradable in the PPY-medium due to the oxidizing environment during incubation. They were also naturally synthesized and released by Tetrahymena cells into the culture medium and increasingly accumulated with time where as noradrenalin demonstrated significant results. Cells were exposed with physiological concentration (0.12 mg/L) and one higher concentration (8.0 mg/L) of catecholamines, resulting noradrenalin depletion and in vivo generation of a metabolite in response to dopamine with higher concentration treatment. This dopamine metabolite was relatively nonpolar compared with the catecholamines and was eluted later from the reverse phase C-18 column.

The hormonal system of the unicellular Tetrahymena: A review with evolutionary aspects

“…In addition to dopamine, epinephrine and kinurenine are synthesized and secreted by the cells [25]. Arteficially added dopamine or L-DOPA is toxic to the cells and decreases norepinephrine synthesis in a very low physiological concentration [26,27].…”