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Starvation induced hypothyroidism involves perturbations in thyroid superoxide‐sod system in pigeons
Author(s) -
Prakash Prem,
Laloraya Malini,
Kumar G Pradeep
Publication year - 1998
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549800202442
Subject(s) - medicine , endocrinology , thyroid , superoxide dismutase , oxidative stress , superoxide , triiodothyronine , hormone , chemistry , iodine , reactive oxygen species , antioxidant , glutathione peroxidase , biology , biochemistry , enzyme , organic chemistry
This study investigated the influence of starvation over seven days on avian thyroidal superoxide radical levels and superoxide dismutase activity profiles in the Indian rock pigeon Columba fivia intermeida, in relation with iodine metabolism. The serum thyroid hormone profile was assayed to correlate the thyroidal redox status with the circulating thyroid hormone levels. The spin‐trapping results suggest a role for thyroidal superoxide anion (O2‐) in causing a hypothyroid state in pigeons during long term energy withdrawal. Pigeons starved for 1 day generated superoxide and iodide free radicals in their thyroids, with a significant decrease in SOD activity. Regain of SOD activity in 2nd‐ and 3rd‐day starved birds is marked by complete scavenging of radicals in the thyroid, suggesting the significance of SOD in thyroid glands as a potential antioxidant sink against reactive oxygen species, O2‐. Resurgence of 02‐ radicals with a parallel decrease in SOD activity in the thyroid gland on 5th‐ and 7th‐day of starvation provides evidence of disruption of homeostasis between pro‐oxidant and antioxidant states, leading to oxidative stress in avian thyroid during long‐term calorie crisis. Following starvation both thyroid hormones thyroxine (T4) and triiodothyronine (T3) decreased, putting pigeons in a hypothyroidstate. We argue that oxidative inactivation of thyroid peroxidase and other thyroid proteins by radical attack during starvation invoked oxidative stress, which could be one of the factors responsible for the hypothyroid state in pigeons.