Subacute toxicity of p,pa super(2)-DDT on rat thyroid: Hormonal and histopathological changes

• Published in: Environmental toxicology and pharmacology 2010-05, Vol.29 (3), p.271-279
• Main Authors: Tebourbi, Olfa, Hallegue, Dorsaf, Yacoubi, Mohamed Tahar, Sakly, Mohsen, Rhouma, Khemais Ben
• Format: Article
• Language: English
• ISSN: 1382-6689
• DOI: 10.1016/j.etap.2010.03.002

The purpose of this study is to assess the effect of p,pa super(2)-DDT on thyroid activity of male Wistar rats. Pesticide was administered intraperitoneally (i.p.) for 10 consecutive days at doses of 50 and 100mg/kg/day. At the end of the treatment, the endpoints examined included serum total levels of triiodothyronine (T3), total thyroxine (T4), and thyroid stimulating hormone (TSH). Thyroid gland histopathology and tissue metabolism of thyroid hormone (T4 UDP-glucuronyltransferase UDP-GT and 5a super(2)-deiodinases) were determined. DDT treatment altered thyroid function namely by increasing hepatic excretion of T4 glucuronide. At the dose of 50mg/kg it decreased T4 circulating levels and increased thyroid 5a super(2)-deiodinase type I (5a super(2)-D-I) and brown adipose tissue (BAT) 5a super(2)-deiodinase type II (5a super(2)-D-II) activities but it did not affect liver 5a super(2)-D-I activity which might contribute to the maintenance of the serum T3 level. Treatment with 100mgDDT/kg decreased serum thyroid hormone concentration and tissue 5a super(2)-D-I activity without affecting BAT 5a super(2)-D-II activity. Gland histomorphological analysis showed hyperplasia and squamous metaplasia with abundant colloid. These observations associated to the elevated serum TSH levels and gland hypertrophy suggest that DDT exposure induced an hypothyroidism state with a colloid goiter in rats.