title: Influence of a melatonin implant on the free radical load in avian thyroid and its relation with thyroid hormonogenesis.
abstract: The primary aim of this study was to evaluate the effect of melatonin on the oxiradical load in avian thyroid. The superoxide free radicals have been spin trapped by EPR spectroscopy in the thyroid gland of Indian rock pigeon Columbia livia following melatonin implantation for two weeks. Melatonin implantation resulted in augmentation in the levels of superoxide radical in the thyroid gland of pigeons with a concomitant decrease in the levels of the total superoxide dismutase activity. This was also associated with increased lipid peroxidation. Melatonin implantation caused a significant increase in plasma levels of glucose. Plasma levels of thyroxine (T4) and triiodothyronine (T3) were lower in the melatonin-treated pigeons. However, the T3/T4 ratio was higher following melatonin implantation. Since iodination of tyrosine is an H2O2-dependent phenomenon, the inhibition in the activity of SOD could lead to impaired thyroid hormone synthesis.
authors.affiliation: School of Life Sciences, Devi Ahilya University, Indore, India.
authors.forename: P
authors.initials: P
authors.lastname: Prakash
authors.forename: M
authors.initials: M
authors.lastname: Laloraya
authors.forename: P
authors.initials: P
authors.lastname: Kumar
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D010856:Columbidae; D004343:Drug Implants; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D013961:Thyroid Gland / Q000187:drug effects / Q000502:physiology*; D013974:Thyroxine / Q000097:blood*; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D001786:Blood Glucose; D004343:Drug Implants; D005609:Free Radicals; D014284:Triiodothyronine; D013481:Superoxides; D013482:Superoxide Dismutase; D008550:Melatonin; D013974:Thyroxine