Selecting In the present study silver nanoparticles were exposed to fish Cyprinus carpio and the changes in the hormonal level were observed. Silver nanoparticles and silver-containing compounds cause adverse effects in human and animals. Environmental pollutants cause an impairment of fish internal function and a characteristic elevation of plasma thyroid hormones. In fish, hormones are critical towards maintaining proper physiological function and amongst the hormones found in fish the thyroid hormones, thyroxine (T4) and triiodothyronine (T3) are known to play an important role in fish growth. Disruption of thyroid axis due to silver nanoparticles may seriously affect normal development, differentiation, growth and reproduction in many fishes. Silver nanoparticles in triiodothyronine (T3) and Thyroxine (T4) level exhibited a significant decrease throughout the study period. Thyroid hormones regulate a wide range of biological processes associated with development, somatic growth, metabolism, energy provision. Thyroid hormone axis poses a significant hazard to human and wildlife health from interference of exogenous salts. The need for development and valid, ion of an in vivo assay for detection of thyroid system disrupting nanoparticles arises from concern that a considerable number of compounds have the potential to interact with different species of thyroid function and thyroid hormone action. The majority of studies on endocrine control functions have concentrated on the suppression of immune response by decreased secretion of thyroid hormone in response to environmental pollution.
