Evaluation of possible goitrogenic and anti-thyroidal effect of nitrate, a potential environmental pollutant.
Nitrate is a wide spread contaminant of ground and surface water. The source of nitrate in the ground water may be from run off or seepage from fertilized soil, municipal or industrial waste water, land fills, septic system, urban drainage or decaying plants. Human and animal systems are affected severely on nitrate exposure. The study was to investigate the effect of dietary nitrate exposure on the thyroid status along with the state of iodine nutrition. Rats were fed diet containing 3% potassium nitrate (KNO3) for 4 weeks and then thyroid status was evaluated by thyroid gland weight, urinary iodine excretion pattern, thyroid peroxidase (TPO) activity, serum levels of total thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) concentrations. In nitrate treated animals, the weight of thyroid gland was increased significantly (P<0.001) while thyroid peroxidase activity (P<0.01), serum T4 (P<0.01) and serum T3 levels (P<0.001) were reduced; but serum TSH level was increased (P<0.001) along with slightly elevated iodine excretion level (P<0.001) in comparison to control animals. The overall results indicated the development of a relative state of functional hypothyroidism with enlarged thyroid after nitrate exposure. This study can explain a part for the persistence of residual goitre in the post-salt iodization phase.
Mukhopadhyay
Sanjukta
S
Endocrinology and Reproductive Physiology Laboratory, Department of Physiology, University of Calcutta, University College of Science and Technology, Kolkata.
Ghosh
Dishari
D
Chatterjee
Aparajita
A
Sinha
Sanchari
S
Tripathy
Smritiratan
S
Chandra
Amar K
AK
D000818:Animals; D001835:Body Weight; D004032:Diet; D004785:Environmental Pollutants / Q000633:toxicity; D006042:Goiter / Q000209:etiology*; D007037:Hypothyroidism / Q000097:blood / Q000139:chemically induced* / Q000652:urine; D007453:Iodide Peroxidase / Q000378:metabolism; D007455:Iodine / Q000502:physiology / Q000652:urine; D009566:Nitrates / Q000008:administration & dosage / Q000633:toxicity*; D009929:Organ Size; D017680:Potassium Compounds / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013961:Thyroid Gland / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014874:Water Pollutants, Chemical
D004785:Environmental Pollutants; D009566:Nitrates; D017680:Potassium Compounds; D014874:Water Pollutants, Chemical; D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D007453:Iodide Peroxidase; D013974:Thyroxine; C023844:potassium nitrate