Effects of waterborne cadmium on thyroid hormone levels and related gene expression in Chinese rare minnow larvae

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 161; pp. 53 - 57
• Main Authors: Li, Zhi-Hua, Chen, Lu, Wu, Yan-Hua, Li, Ping, Li, Yun-Feng, Ni, Zhao-Hui
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2014
• Subjects: Animals; Cadmium; Cadmium - adverse effects; Cadmium Poisoning; Chinese rare minnow; Down-Regulation - drug effects; Down-Regulation - genetics; Environmental Exposure; Fishes - metabolism; Freshwater; Gene expression; Gene Expression - drug effects; Gobiocypris rarus; Hypothalamic–pituitary–thyroid axis; Hypothalamo-Hypophyseal System - drug effects; Hypothalamo-Hypophyseal System - metabolism; Larva - drug effects; Larva - genetics; Larva - metabolism; RNA, Messenger - genetics; Thyroid Gland - drug effects; Thyroid Gland - metabolism; Thyroid hormone; Thyroid Hormones - metabolism; Thyroxine - metabolism; Up-Regulation - drug effects; Up-Regulation - genetics; Water Pollutants, Chemical - poisoning; Cadmium; Hypothalamic–pituitary–thyroid axis; Thyroid hormone; Chinese rare minnow; Gene expression
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2014.02.001

Cadmium is a heavy metal abundant in the environment that can induce endocrine disorder and toxicity in aquatic organisms at low levels. However, its effects on the thyroid system in fish are still unclear. In this study, the thyroid hormone (TH) levels and the expression profiles of genes related to hypothalamic– pituitary–thyroid (HPT) axis, including corticotropin-releasing hormone (crh), thyroid stimulating hormone beta (tshβ), solute carrier family 5 (sodium iodide symporter) member 5 (slc5a5), thyroglobulin (tg), thyroid hormone receptor alpha (trα) and thyroid hormone receptor beta (trβ), were determined in whole body of Chinese rare minnow (Gobiocypris rarus) larvae after exposure to different levels of Cd2+ (0, 0.5 and 2.5mg/L) for 4days. And the 96-h lethal concentration of Cd2+ on rare minnow larvae was determined as 2.59mg/L. The results showed that crh, slc5a5, tg and tshβ mRNA levels were significantly up-regulated in the larvae, but the gene expression of trα and trβ was down-regulated in a concentration-dependent manner. Besides, the THs levels decreased in the whole-body of fish, especially the thyroxine (T4) level. The above results indicated that Cd2+ could alter gene expression in the HPT axis that might subsequently contribute to thyroid disruption.