Iodine indirect effect on thyroid gland: structure and hormone receptor (TRα) in common sole, Solea solea larvae

Abstract

The effect of feeding Solea solea with Artemia enriched in iodine during metamorphosis was evaluated. In the present study, three treatment groups were used; i) control fish fed with untreated Artemia, ii) low dose (TLow), in which sole were fed with instar Ӏ Artemia exposed to potassium iodate® (0.1g IKO3/L) for 3 hours and iii) high dose (Thigh), in which sole were fed with instar Ӏ Artemia exposed to potassium iodate® (0.2 g IKO3/L,). Growth performance, thyroid follicles (localization and morphometric analysis), and thyroid hormone receptor (TRα) were measured. A significant increase in the expression of thyroid hormone receptor type 1 (TRα) occurred in the iodine supplemented larvae and was 3.55±1.13 fold higher than the control. The thyroid gland was not significantly modified in the group fed on Artemia supplemented with iodine; indicating that iodine-supplementation for sole post-larvae is unnecessary in open circuit seawater systems.