Effect of Ascorbic Acid on Long-Term Cold Exposure Induced Changes in Thyroid Activity in Sprague Dawley Rats

Objective: To determine the effect of ascorbic acid supplementation on long-term cold exposure induced changes in thyroid activity in Sprague-Dawley rats. Study Design: Experimental study. Place and Duration of Study: Physiology Department of Islamic International Medical College, Rawalpindi, National Institute of Health, Islamabad and Railway Hospital, Rawalpindi, from January to December 2009. Methodology: Ninety Sprague-Dawley rats were randomly divided into three groups of control, cold exposed and cold exposed along with ascorbic acid supplementation. After one month, their thyroid levels were analyzed by using chemiluminescent immunometric Assay on Siemens lmmulite 2000 Analyzer. Results: After 4 weeks of cold exposure to experimental animals, the thyroid activity was raised significantly in the cold exposed group as compared to the control group (p-value for T-3 difference = 0.004, T-4 difference = 0.002 and TSH difference < 0.001). Supplementation with ascorbic acid in the third group normalized the thyroid hormone activity with p-value for difference in levels of T-3 being 0.6661, T-4 = 0.027 and TSH = 0.0028. Conclusion: Ascorbic acid prevented the cold induced changes in thyroid hormone levels in rodents.