The effects of high dose of iodine on the anatomical and histological features of the thyroid glands in rabbits during the prenatal and postnatal periods

Soran Mustafa Karim


Background and objectives: Iodine is an essential nutrient for optimal thyroid function, the major health effects of concern with excess iodine ingestion are thyroid disorders. The purpose of this study was to investigate the effects of the toxic dose of iodine on the anatomical and histological features of the thyroid glands in rabbits during prenatal and postnatal periods.
Methods: Thirty two adult female rabbits were selected. Only sixteen female rabbits were given oral dose of iodine (11 mg/kg of body weight dissolved in 1ml of distilled water) twice daily for a period of one and a half month, then rabbit offspring’s thyroid glands were studied anatomically and histologically.
Results: The study group showed significantly higher rate of thyroid glands developmental disturbances (p<0.05), significant in- crease in thyroid glands weight in the postnatal period only (p<0.05), and in the thyroid gland volume in the prenatal period at 21th day of gestation and postnatal periods (p<0.05). Histological analysis showed significant decrease in heights and increase in widths of follicular cells (p<0.05) in the study group at postnatal periods. The thyroid tissues at 21 th day of gestation in the control and study embryos were nearly similar in the diameter of the follicles, but the number of the follicles in the study group was significantly less than the control group (p<0.05). The study group in postnatal periods showed significantly lesser number of follicles but with larger diameter and the colloid showed cracking. A significant decrease in the blood vessels density was also seen (p<0.05).
Conclusion: High dose of iodine causes goitrogenic effect which may induces the blockade of hormone biosynthesis.


Iodine, thyroid gland, rabbit.

Full Text:



Longo D, Fauci A, Kasper D, Hauser S .Harrisons Principles of Internal Medicine. 18th ed. New York, McGraw Hill. 2011; p.


Konno N, Makita H, Yuri K, et al. Association between dietary iodine intake and prevalence of subclinical hypothyroidism the coastal regions of Japan. J Clin Endocrinol Metab. 1994; 78:393–97.

Zhao JK, Chen ZP, Maberly GF. Iodine-rich drinking water of natural origin in China. Lancet. 1998; 352: 60.

Martino E, Bartalena L, Bogazzi F, Braverman LE. The effects of amiodarone on the thyroid. Endocr Rev. 2001; 22:240–54.

Wolff J. Physiology and pharmacology of iodized oil in goiter prophylaxis. Medicine. 2001; 80:20–36.

Michael B. Iodine: Its role in health and disease. J Hlth and Wellbeing. 2010; 10: 89-98.

Baker HJ, Lindsey JR. Equine goiter due to excess dietary iodide. J Am Vet Med Assoc. 2004; 153:1618-30.

Delange F. Optimal iodine nutrition during pregnancy, lactation and neonatal period. Endocrine In J. 2004; 2: 1-12.

Arthur C. John E .Text book of Medical Physiology.11th ed. New York, Elsevier-Saunders; 2009.p. 903-39.

Fabian H , Harald B , Axel K , Gerald M , Gerd G. Prospective study to determine the penetration of io- dide following preoperative application of topical 1.25% povidone-iodine. J Clin Exp Opthalmol. 2008;245 : 789-93.

Roberto M, Mirko D, Marco F. Thyroid volumetric quantification, comparative evaluation between con- ventional and volumetric ultrasonography. J Ultrason Med .2008; 27 :1727-33.

Hu F, Sharma B, Mukhi S, Patin ̃o R, Carr JA. The colloidal thyroxine (T4) ring as a novel biomarker of perchlorate exposure in the african clawed frog xenopus laevis. Toxicological sciences. 2006; 93, 268–77.

Nishiyama S, Mikeda T, Okada T, Nakamura K, Kotani T, Hishinuma A.Transient hypothyroidism or persistent hyperthyrotropinemia in neonates born to mothers with excessive iodine intake. Thy J. 2004 ; 14:1077–83.

Xue F,Yang X F, Jian X, et al. Developmental toxic effects of chronic exposure to high dose of iodine in the mouse. Repro

Toxicol J. 2006;22:725-30.

Guo Z, Narbaitz R, Fryer JN. Effects of excess iodine in chick emberyo thyroid follicles,initial inhibition and subsequent

hypertrophy. J Anat. 1991; 176:157-67.

Zimmermann MB, Ito Y, Hess SY, et al. High thyroid volume in children with excess dietary iodine in- takes. Am J Clin Nutr.

; 81:840- 44.

Castillo V, Lalia J, Junco M. Changes in Thyroid Function in Puppies Fed a High Iodine Commercial Diet. Colombian Vet J

. 2003; 161: 80 - 4.



  • There are currently no refbacks.


Copyright by Iraqi Dental Journal

ISSN (Print): 2307-4779 | ISSN (Online): 2411-9741