Can aquatic pollutants cause specific endocrinological and metabolic responses in salmon (Salmo salar m. sebago) embryos? - A direct calorimetry study

摘要

Aquatic wildlife has been identified to be at risk of adverse effects from endocrine disrupting chemicals (EDC). The major concern has been in chemicals that mimic or block the action of hormones at their receptor molecules in association with reproductive endocrine function (e.g. Cambpell Hutchinson 1998). However, chemicals can affect also other vertebrate target organs and endocrine functions. For example, the thyroid is of concern because its hormones regulate many metabolic processes. In teleost fish, these hormones are critical for normal development, growth and reproduction, and thyroid disruption could compromise fitness and survival (Brown et al. 2004 and references therein). Interestingly, thyroid hormones (TH) in fish eggs are known to be of maternal origin during the earliest phases of development (Kobuke et al. 1987). The levels of thyroid hormones decrease gradually during the development until the embryonic hormone production initiates (Raine Leatherland 1999). Earlier studies have shown that external administration or blocking of thyroid hormones may have effects on processes such as hatching, survival, growth and yolk absorption in fish embryos (Reddy Lam 1992). These observations indicate that the thyroid hormones are important in embryos even though their exact role in development is not fully understood. The function of thyroid hormones also suggests that thyroid-disrupting toxicants may have energetic consequences by affecting regulation of metabolic rate. In fish eggs, metabolic rate increases throughout the early development and therefore associations, if any, of the metabolic rate with thyroid hormones and pollutants required study.