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Thyroid hormones, their importance and exposure to cold
Špínová, Šárka ; Žurmanová, Jitka (advisor) ; Krulová, Magdaléna (referee)
Thyroid hormones are essential mainly for prenatal development and they maintain the homeostasis of many organs and body processes in adulthood. Therefore, the correct function of the regulatory axis between the hypothalamus, pituitary gland and thyroid gland is very important. Lack of these hormones is manifested, for example, by the formation of goiter, cretenism and bradycardia, excess in weight loss, ophthalmopathy, excessive sweating, tachycardia and also goiter formation. A serious problem is also the mutation of thyroid hormone receptors in target tissues. It causes nervous system disorders, hearing, vision, digestive system, incorrect cardiac function, delayed growth and mental development. Thyroid hormones are essential for the formation and activation of brown adipose tissue. This, together with the shivering thermogenesis of skeletal muscle, is involved in facultative thermogenesis, helping homoeothermic mammals to maintain a constant body core temperature. In addition, brown adipose tissue is an important endocrine organ that secretes active substances called batokines upon cold activation. Batokines have beneficial effects in the treatment of obesity, diabetes and cardiovascular disease. So we can assume that cold adaptation could effectively help in the treatment of civilization...
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The effect of iodine on functional parameters of ewes.
DUŠOVÁ, Hana
The aim of this work was to assess the long-term effect of excessive iodine intake on thyroid activity and selected immunological, haematological and biochemical parameters in blood of ewes and their lambs. The experiment was conducted from August 2009 to February 2010 in an experimental barn of Faculty of Agriculture, University of South Bohemia in České Budějovice. Into the experiment were used Šumava sheep breed ewes and their born lambs. Group A (control) consisted of 6 ewes after lambing was extended to 7 born lambs, group B (experimental) 6 of 6 ewes and lambs. Lambs were put into the experiment from the 1st to the 60th day after birth and received iodine in the milk of their mothers. Iodine supplementation to the diet of ewes was launched during the first to second months of pregnancy and finished 60 days after birth. During the experiment, a group of ewes A received 3,1 and group B 5,1 mg iodine per kg of dietary dry matter in the form of calcium iodate. During the experiment was regularly collected blood of ewes (before lambing and 1st, 10th, 30th and 60th day after birth) and lambs (1st, 3rd, 10th, 30th and 60th day after birth) to determine the concentration of thyroid stimulating hormone and immunoglobulin G (ELISA) in blood serum, thyroid hormones (RIA), total protein, urea and alkaline phosphatase activity in the blood plasma (biochemical analyser), the content of haemoglobin, white blood cell´s and red blood cell´s counts and haematocrit values in blood (haematological analyser), percentage of albumin, -1-globulins, -2-globulins, -globulins, and -globulins in blood serum (electrophoresis) and the content of iodine in the blood plasma, urine and milk of ewes (colorimetric method Sandell-Kolthoff). During the experiment were not observed in ewes and lambs clinical symptoms associated with an excessive intake of iodine. In experimental group of ewes with iodine intake 5,1 mg/kg of dietary dry matter were found higher values of thyroid stimulating hormone, lower values of free triiodothyronine, free thyroxine, IgG, white blood cells, -1-globulins, -2-globulin and -globulin, significantly lower values of -globulins after parturition, significantly higher values of urea and alkaline phosphatase activity. The iodine content in blood plasma, milk and urine of ewes is increased in direct proportion to its concentration in diet. Lambs of mothers with iodine intake of 5,1 mg/kg of dietary dry matter were significantly higher values of thyroid stimulating hormone from the 10th day after birth, significantly lower values of free triiodothyronine and free thyroxine first day after birth, immunoglobulin G and -globulins in 30th day after birth, lower (statistically significant in middle samples) values of total protein and white blood cells, higher values of urea and alkaline phosphatase activity. The weight gains of lambs were not significantly affected by iodine supplementation. These results in ewes with iodine intake of 5,1 mg/kg dietary dry matter and especially their lambs drawn to risk of reduce the activity of the thyroid gland and the negative impact of parameters of humoral immunity, mainly IgG and -globulins.
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