Effect of Transient Thyrotoxicosis and Hypothyroidism on the Rheoreaction of Zebrafish Danio rerio (Cyprinidae)

Abstract The effect of transient thyrotoxicosis and hypothyroidism on the metabolism and rheoreaction of zebrafish Danio rerio has been studied. Thyrotoxicosis was induced by administrating triiodothyronine (T 3 ) at a concentration of 10 ng/mL in aquarium water. Hypothyroidism was provoked by suppressing the thyroid activity with goitrogen, 0.05% thiourea. It has been found that thyrotoxicosis leads to an increase in the standard metabolic rate, whereas hypothyroidism causes its decrease, as well as a decrease in the swimming performance of the experimental fish. The concentration of T 3 affects the locomotor activity and characteristics of the motivational component of the zebrafish rheoreaction. The higher the concentrations of T 3 , the greater the probability of the positive type of rheoreaction (fish movements against the current).