allopurinol and Thyroid-Diseases

Free radicals, hydroxyperoxides and H(2)O(2) are all known to damage cell components. This study was designed to compare the concentrations of hydroxyperoxide and free radical scavengers in the cardiac muscles of old rats in the hyper- or hypothyroid condition, to determine whether rates of peroxidation would differ with age, thyroid status, or both. Rats were rendered hyper- or hypothyroid by administration of l-thyroxine or methimazole for 4 weeks. Among the old rats, the lipid peroxide (LPO) concentrations, measured as thiobarbituric acid (TBA) reactants, were significantly greater in the hyperthyroid than in the euthyroid state and the LPO concentrations measured as TBA+Fe(3+) reactants, which may be precursors of LPO, were significantly greater in the hyperthyroid state, whereas in young rats, the LPO concentrations measured by TBA or TBA+Fe(3+) methods did not differ significantly in the hyperthyroid state. In the euthyroid state, the concentration of LPO measured as TBA+Fe(3+) reactants was significantly reduced with age. Xanthine oxidase (XOD) activity also was markedly increased with age, being more pronounced in the hyperthyroid than in the euthyroid state. The Mn and Cu/Zn superoxide dismutase activities were greater in the hyperthyroid than in the euthyroid state. Glutathione peroxidase activity decreased with age in the euthyroid and, particularly, in the hyperthyroid state. Catalase activity was not affected in the old rats. Concentrations of alpha-tocopherol in the old rats were high in the hyperthyroid state and low in the hypothyroid state, whereas the levels of beta- and gamma-tocopherols in these rats were unchanged in both conditions as compared with the euthyroid state findings. Data suggest that the site of free radical generation differs in older rats, with additional shifts in the location of intracellular lipid peroxidation being noted during hyperthyroidism. Thus, as rats age, the reduction of the free radical scavenger system and the increase in LPO and XOD activities might induce myocardial dysfunction.

Topics: Aging; Analysis of Variance; Animals; Antithyroid Agents; Glutathione Peroxidase; Hyperthyroidism; Hypothyroidism; Lipid Peroxidation; Male; Malondialdehyde; Methimazole; Myocardium; Rats; Rats, Wistar; Superoxide Dismutase; Thyroid Diseases; Thyroid Gland; Thyroxine; Vitamin E; Xanthine Oxidase

The effect of thyroid hormones on the hepatic xanthine oxidase activity was studied in rats after the intraperitoneal injections of comthyroid (triiodotyronine:thyroxine = 1:4) at 0.3 mg/kg for 3 consecutive days. The aim of this study was to understand the precise mechanism of hyperthyroidism induced by oxidative stress. The concentration of lipid peroxides determined indirectly by the measurement of thiobarbituric acid reactants was increased in comthyroid treated rats. The hepatic glutathione content was decreased in comthyroid injected rat compared to the euthyroid state. It was also observed that the increment of xanthine oxidase activity has a profound role in oxygen radicals generation system in comthyroid treated rat. These findings suggest that the enhanced xanthine oxidase activity and depleting glutathione content in comthyroid treated rats result in pathophysiological oxidative stress including an increment of hepatic lipid peroxidation.

Topics: Animals; Body Temperature; Free Radicals; Glutathione; Lipid Peroxidation; Liver; Male; Oxidative Stress; Proteins; Rats; Rats, Sprague-Dawley; Thyroid Diseases; Thyroid Hormones; Xanthine Dehydrogenase; Xanthine Oxidase

To clarify whether the changes of free radicals and its scavengers are induced by thyroid disorders, we measured levels of free radical scavengers and checked O2 radical generating systems in the human thyroid gland. Thyroid specimens from patients with Graves' disease, follicular adenoma, and papillary and follicular carcinomas contained significantly higher concentrations of xanthine oxidase (XOD) and gluthathione peroxidase (GSH-PX), compared to those in the normal thyroid tissue. Catalase concentration was significantly lower in thyroid specimens from patients with Graves' disease and significantly lower in thyroid specimens from patients with follicular adenoma, compared to those in the normal thyroid tissue. Cu/Zn superoxide dismutase (Cu/Zn SOD) concentration was significantly lower in the specimens from follicular adenoma and papillary carcinoma and Mn SOD concentration was significantly higher in the specimens from papillary carcinoma than those in the normal thyroid tissue. The lipid peroxide concentration, expressed as malondialdehyde (MDA) concentration, was significantly higher in the specimens from papillary carcinoma than those in the normal thyroid tissue. These findings suggest that the levels of free radicals are increased and are scavenged and catalyzed in the thyroid of Graves' disease, whereas free radicals and lipid peroxide are not completely scavenged in papillary carcinoma tissues, suggesting that these substances affect some role in cell function of thyroid tumors.

Topics: Adenocarcinoma, Follicular; Adenocarcinoma, Papillary; Adenoma; Catalase; Free Radicals; Glutathione Peroxidase; Graves Disease; Humans; Lipid Peroxidation; Reactive Oxygen Species; Thyroid Diseases; Thyroid Gland; Thyroid Neoplasms; Xanthine Oxidase

A total of 2,923 elderly subjects were studied to determine the relationship between obesity, hypertension, thyroid disease, renal function, alcohol consumption, selected drugs, and the serum uric acid level. Comparison of the serum uric acid levels with indices of obesity demonstrated a strong correlation in normotensive (p less than .0001) and hypertensive (p less than .001) subjects. The serum creatinine level, when used alone, was not a reliable indicator of renal function. Of the drugs evaluated, diuretics had the most pronounced effect upon the serum uric acid level.

Topics: Aged; Allopurinol; Diuretics; Female; Humans; Hypertension; Male; Obesity; Probenecid; Thyroid Diseases; Uric Acid