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Journal Article 2006; 27(1-2): 247-252 PubMed PMID: 16648789 Citation  Keywords:  Adolescent, Adult, Exercise:physiology, Exercise Test, Humans, Testosterone:blood, Thyroid Hormones:blood, Thyrotropin:blood, Thyroxine:blood, Triiodothyronine:blood, Wrestling:physiology, Zinc:pharmacology,.   

OBJECTIVES: The present study aims to investigate how exhaustion exercise affects thyroid hormones and testosterone levels in elite athletes who are supplemented with oral zinc sulfate for 4 weeks.

METHODS: The study included 10 male wrestlers, who had been licensed wrestlers for at least 6 years. Mean age of the wrestlers who volunteered in the study was 18.70 +/- 2.4 years. All subjects were supplemented with oral zinc sulfate (3 mg/kg/day) for 4 weeks in addition to their normal diet. Thyroid hormone and testosterone levels of all subjects were determined as resting and exhaustion before and after zinc supplementation.

RESULTS: Resting TT3, TT4, FT3, FT4 and TSH levels of subjects were higher than the parameters measured after exhaustion exercise before zinc supplementation (p<0.05). Both resting and exhaustion TT3, TT4 and FT3 values after 4-week zinc supplementation were found significantly higher than both of the parameters (resting and exhaustion) measured before zinc supplementation (p<0.05). Resting total testosterone and free testosterone levels before zinc supplementation were significantly higher than exhaustion levels before zinc supplementation (p<0.05). Both resting and exhaustion total and free testosterone levels following 4-week zinc supplementation were found significantly higher than the levels (both resting and exhaustion) measured before zinc supplementation (p<0.05).

CONCLUSION: Findings of our study demonstrate that exhaustion exercise led to a significant inhibition of both thyroid hormones and testosterone concentrations, but that 4-week zinc supplementation prevented this inhibition in wrestlers. In conclusion, physiological doses of zinc administration may benefit performance....

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Journal Article 2006; 27(1-2): 231-235 PubMed PMID: 16648777 Citation  Keywords:  Adult, Alcoholism:enzymology, Alleles, Amino Acid Substitution, Catechol O-Methyltransferase:genetics, DNA:genetics, Female, Gene Frequency, Humans, Japan:epidemiology, Male, Middle Aged, Mutation:physiology, Polymorphism, Genetic:genetics, Polymorphism, .   

OBJECTIVES: The catechol-O-methyltransferase (COMT) is an enzyme involved in the metabolism of dopamine, adrenaline and noradrenaline. The Val158Met polymorphism of the COMT gene has been previously associated with a variability of the COMT activity, and alcoholism. The aim of the present association study was to examine the relationship between the Val158Met polymorphism of the COMT gene and dispositions to alcoholism.

METHODS: In our case control study we analyzed DNA samples from 799 subjects in total (279 male alcoholics and 120 female alcoholics, 151 male controls and 249 female controls). The restriction analysis for the detection of the Val158Met polymorphism was used.

RESULTS: We found a relationship between the Val158Met polymorphism of the COMT gene and alcoholism in male subjects. We found the significant difference between male alcoholics and male controls in allele and genotype frequencies (p<0,007; and p<0,04 respectively).

CONCLUSIONS: Our study confirmed the relationship between the COMT polymorphism and alcoholism in the Czech male population....

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Clinical Trial 2005; 26(6): 830-834 PubMed PMID: 16380698 Citation  Keywords:  Adult, Analysis of Variance, Energy Metabolism:physiology, Exercise:physiology, Heart Rate:physiology, Humans, Male, Physical Exertion, Reference Values, Statistics, Nonparametric, Thyrotropin:blood, Thyroxine:blood, Triiodothyronine:blood,.   

BACKGROUND: Physical activity influences energy metabolism in human subjects by increasing activity-induced energy expenditure and resting metabolic rate for several hours after exercise. Effects of exercise on circulating thyroid hormone values remain controversial. We have investigated the effect of acute aerobic exercise on thyroid hormone values.

MATERIALS/METHODS: The effect of different intensity levels of acute aerobic exercise on thyroid hormones was investigated in 60 male well-trained athletes by performing bicycle ergometer at 45% (low intensity), 70% (moderate intensity), and 90% (high intensity). These intensities were selected according to their maximum heart rate (MHR). At each intensity level, heart rate, blood lactic acid, serum total thyroxine (T4), free thyroxine (fT4), total triiodothyronine (T3), free triiodothyronine (fT3) and thyroid stimulating hormone (TSH) values were measured.

RESULTS: The results of this study show that exercise performed at the anaerobic threshold (70% of maximum heart rate, lactate level 4.59 +/- 1.75 mmol/l) caused the most prominent changes in the amount of any hormone values. While the rate of T4, fT4, and TSH continued to rise at 90% of maximum heart rate, the rate of T3 and fT3 started to fall.

CONCLUSIONS: Maximal aerobic exercise greatly affects the level of circulating thyroid hormones....

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Comparative Study 2005; 26(6): 780-788 PubMed PMID: 16380692 Citation  Keywords:  Age Factors, Animals, Animals, Newborn:physiology, Body Weight:physiology, Corticosterone:blood, Female, Germ Cells:cytology, Hydroxysteroid Dehydrogenases:metabolism, Hypothyroidism:chemically induced, Luteinizing Hormone:blood, Male, Organ Size, Pregnan.   

OBJECTIVE: Effects of transient neonatal hypothyroidism (HPOT) on adult testis size and serum hormone profiles were evaluated in the Charles foster strain of rats, maintained under the temperature of 21 degrees C (HPOTL) or of 34 degrees C (HPOTH).

METHODS: Hypothyroidism was induced in suckling pups in preweanling period (1-21 days), by administering 0.1% 6-propyl-2-thiouracil in drinking water to mothers. Body mass and testis characteristics, the steroidogenic potential [measured by histochemical localization of 3alpha-, 3beta- and 17beta-hydroxysteroid dehydrogenases (HSDHs)] and serum concentrations of thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), luteinizing hormone (LH), testosterone (T) and corticosterone (Cort) were evaluated on the 35th, 45th, 60th and 90th day of age.

RESULTS: The HPOTH rats showed lower testis masses, while the HPOTL rats showed higher testis masses and lower body masses after 90 days. Histologically, the testes of the HPOTH rats demonstrated increased germ cell degeneration after 35 and 45 days and reduced tubular size, germ cell numbers and sperm density after 90 days. In contrast, the testes of the HPOTL rats showed reduced tubular diameters after 35 and 45 days, and increased tubular diameters, germ cell numbers and sperm density after 90 days. Serum TSH, T3, T4, LH and T concentrations and 3beta- and 17beta-HSDH activities were reduced in both groups of the HPOT rats after 35 and 45 days. Intratubular steroidogenesis and a prominent triangle up5 pathway were also found in the HPOT animals.

CONCLUSION: The temperature has a definite influence on the thyroid hormone action, postnatal growth and function of rat testes....

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Comparative Study 2005; 26(6): 795-798 PubMed PMID: 16380688 Citation  Keywords:  Animals, Antioxidants:metabolism, Brain:enzymology, Glutathione:metabolism, Hyperthyroidism:metabolism, Lipid Peroxidation:physiology, Liver:enzymology, Male, Malondialdehyde:metabolism, Myocardium:enzymology, Pineal Gland:physiology, Rats, Rats, Sprague-.   

OBJECTIVE: Thyroid hormones regulate energy metabolism and act on the mitochondria, which is an important source of free radicals in the cell. Reactive oxygen types play a significant role in physiological mechanisms, but in excessive amounts they can cause oxidative damage in molecules. The aim of the present study was to determine levels of lipid peroxidation caused by induced hyperthyroidism in cerebral, hepatic and cardiac tissues of pinealectomized rats.

METHODS: Experimental animals used in the study were allocated to three groups as general control group, hyperthyroidism-sham pinealectomy group and hyperthyroidism-pinealectomy group. GSH and MDA levels in cerebral, hepatic and cardiac tissues were evaluated at the end of the 3-week study period.

RESULTS: It was found that MDA levels in cerebral, hepatic and cardiac tissues were the highest in hyperthyroidism and pinealectomy group and that these values were higher in hyperthyroidism-sham pinealectomy group than in the control group (p<0.001). It was seen that tissue GSH levels significantly increased in hyperthyroidism-sham pinealectomy group (p<0.001) and that the increase in hyperthyroidism and pinealectomy group was higher than the increase in the control group only (p<0.001).

CONCLUSION: Results of our study show that MDA and GSH levels in cerebral, hepatic and cardiac tissues increased due to hyperthyroidism and that the increase in MDA levels became more evident and GSH levels were significantly suppressed after pinealectomy....

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Comparative Study 2005; 26(6): 806-810 PubMed PMID: 16380687 Citation  Keywords:  Animals, Glutathione:metabolism, Hyperthyroidism:chemically induced, Kidney:metabolism, Lipid Peroxidation, Male, Malondialdehyde:metabolism, Melatonin:metabolism, Oxidative Stress:physiology, Rats, Rats, Sprague-Dawley, Testis:metabolism, Thyroxine,.   

OBJECTIVE: The present study aimed at determining how 3-week intraperitoneal melatonin administration affected oxidative stress caused by experimental hyperthyroidism.

MATERIALS AND METHODS: The study was conducted on 30 male rats of Sprague-Dawley species. The experimental animals were divided to 3 groups (control, hyperthyroidism and hyperthyroidism+melatonin). The supplementation was continued for 3 weeks after which the animals were sacrificed and tissue malondyaldehyde (MDA) and glutathione (GSH) levels were determined.

RESULTS: MDA levels in kidney and testis tissues in hyperthyroidism group were higher than those in control and hyperthyroidism+melatonin administered groups (p<0.001) and levels in hyperthyroidism+melatonin administered group were higher than those in the control group (p<0.001). The highest GSH levels were obtained in hyperthyroidism+melatonin-administered group (p<0.001) and GSH levels in hyperthyroidism group were higher than those in the control group (p<0.001).

CONCLUSION: Results of the study demonstrate that hyperthyroidism induced by 3-week L-thyroxine administration increased oxidative stress in kidney and testis tissues and that although melatonin administration inhibited this stress to a certain extent, it could not bring the stress down to the level in controls....

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Comparative Study 2005; 26(6): 704-708 PubMed PMID: 16380675 Citation  Keywords:  Analysis of Variance, Animals, Antioxidants:pharmacology, Antithyroid Agents:pharmacology, Brain:metabolism, Hydrocarbons:metabolism, Lipid Peroxidation:physiology, Male, Malondialdehyde:metabolism, Melatonin:metabolism, Neuroprotective Agents:metabolism,.   

OBJECTIVE: It is known that thyrotoxicosis induces lipid peroxidation (LPO). In contrast, propylthiouracil (PTU), a thyrostatic drug is a well-known antioxidant. Also melatonin has been shown to protect against free radical-induced neuronal destruction. At the same time, it is generally accepted that the brain is the most vulnerable tissue to oxidative stress.

METHODS: The goal of the study was to examine the components of LPO, i.e., conjugated dienes (CD), malondialdehyde (MDA) and Schiff's bases (SB), in the brain of male Wistar rats. Two experiments were performed, with two control groups created for each experiment: Group 1--intact animals and Group 2--animals injected with 0.9% NaCl. In Experiment I, the animals received L-thyroxine (L-T4) in a dose of 100 microg/kg BW, i.p., daily, for two weeks (Groups 3-5). After one week of L-T4 treatment, the following agents were added during a subsequent week: Group 4--PTU in drinking water (45 mg/kg BW/day); Group 5--melatonin (5 mg/kg BW, daily). In Experiment II, lasting 7 days, the animals were divided into the following groups: Group 1--intact animals; Group 2--animals injected with 0.9% NaCl; Group 3--PTU in drinking water (45 mg/kg BW/day); Group 4--melatonin (5 mg/kg BW, daily).

RESULTS: In Experiment I, we observed a significantly higher SB level in saline treated animals and a significant increase in both CD and SB levels in rats treated with L-T4, compared to those in non treated control. CD levels were also elevated in rats treated with L-T4, compared to values in the saline only treated animals. Melatonin and PTU reduced CD levels and melatonin diminished SB levels, as compared to those in L-T4-treated rats. In Experiment II, we observed significantly higher CD, SB and MDA levels in saline treated rats, when compared to respective values in non treated control. Melatonin decreased CD levels, when compared to CD levels in both the non treated and saline injected controls. Additionally, melatonin reduced SB levels relative to change in the brains of saline treated rats. Furthermore, PTU decreased CD levels in brain homogenates compared to non-treated animals.

CONCLUSIONS: (1) L-thyroxine administration stimulates LPO in the rat brain; (2) All the examined antioxidants decrease LPO in L-T4-administered animals; (3) All the examined antioxidants reduce the basal LPO; 4) Stress, when induced by handling, intensifies oxidative processes in the organism....

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Journal Article 2005; 26(5): 536-540 PubMed PMID: 16264404 Citation  Keywords:  Animals, Antithyroid Agents, Cholesterol:blood, Folic Acid:blood, Homocysteine:blood, Hyperthyroidism:blood, Hypothyroidism:blood, Lipids:blood, Male, Propylthiouracil, Rats, Rats, Wistar, Thyroid Function Tests, Thyroxine, Vitamin B 12:blood,.   

INTRODUCTION: It is claimed in a limited number of studies carried out on human beings that plasma homocysteine levels increased in hypothyroid patients and decreased in hyperthyroid patients.

OBJECTIVE: The aim of this study is to determine total plasma homocysteine, thyroid function tests, vitamin B12, folic acid and lipid levels and to explore the relations among them in rat models with induced hypothyroidism and hyperthyroidism with a view to investigating whether hypothyroid and hyperthyroid rat models could represent human hypothyroidism and hyperthyroidism models.

MATERIAL AND METHOD: The study included 30 male Wistar Albino species rats with a mean weight of 200 - 250 g. Rats were randomly divided into 3 groups as 1) hypothyroid group, 2) hyperthyroid group and 3) control group. Hypothyroidism was induced by adding 10 mg/kg/day propylthiouracil to rats' drinking water for 30 days. In order to induce hyperthyroidism, rats were administered 10 microg/100 g L-thyroxin ampule via intraperitoneal route for 10 days.

RESULTS: We found that total plasma homocysteine level of the hypothyroid group was significantly lower than those of the control group (p<0.05) and the hyperthyroid group (p<0.001). Total plasma homocysteine level of the hypothyroid group was found insignificantly higher than that of the control group (p>0.05) and significantly higher than that of the hyperthyroid group (p<0.001). We established a significant and positive correlation between total plasma homocysteine level and thyroid hormone levels. We did not identify a significant relation between total plasma homocysteine level and serum folic acid and serum vitamin B12 levels.

CONCLUSION: Our findings are different from the findings reported in human hypothyroidism and hyperthyroidism studies. We believe that hypothyroid and hyperthyroid rat models cannot represent human hypothyroidism and hyperthyroidism models....

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