Endocrine Abstracts

Oxidative stress is regarded as a pathogenic factor in hyperthyroidism. IL6 has been described as acting as a protective intrahepatocellular against oxidative stress and mitochondrial dysfunction. On the opposite way leptin has been shown to increase oxidative stress. The impact of thyroid hormones on circulating cytokines levels has been demonstrated with conflicting results both in human and rats. Most of the studies concerned hyperthyroidism showed increased levels of IL6 compared either with controls. Our purpose was to determine the effect of hyperthyroidism and hypothyroidism on the concentration of IL6 in different tissues and leptin serum concentration. Male Wistar rats (60 days of age) were randomly distributed into three different groups: C – control group that received daily i.p. injection of vehicle; Hyper – hyperthyroid rats group that received daily i.p. injection of T₄ (50 μg/rat); Hypo- hypothyroid rats group that received daily i.p. injection of propylthiouracil (50 μg/rat). 21 days after treatment, the animals were killed and serum, retroperitoneal adipose tissue, EDL and soleum muscles, and liver were collected. Tissues IL6 level, body weight gain, serum lipid profile, leptin and insulin were determined. The serum lipid profile and body weight gain and food consumption were similar among groups. All analysed parameters were similar between Hypo and C. However, the Hyper showed: increase in liver and EDL IL6 level; decrease in serum leptin levels; and elevation in insulin and glucose serum concentration. These results demonstrated that 21 days of propylthiouracil treatment did not affect the analysed parameters. However, the increase in tissues IL6 content and decrease leptin levels in T₄ treated group could be a compensatory modulation of the oxidative stress caused by hyperthyroidism state.