Diurnal Effect of Selenium Supplementation on Adult Female Wistar Rats made Hypothyroid by Methimazole
Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2017, Vol 1, Issue 2
Abstract
Diurnal variation in gastric emptying is known to affect the bioavailability of ingest. The present study sought to understand the effect of consumption of selenium in daytime or nighttime on some clinical features of hypothyroidism in female wistar rats. 36 adult female wistar rats weighing 120-150g were randomly divided into 6 groups: vehicle-treated, methimazole, daytime – selenium, nighttime-selenium, methimazole+ daytime-selenium and methimazole+ nighttime selenium groups. Hypothyroidism was induced through oral administration of 1.35mg/kg body weight of methimazole. 7mg/ml of Selenomethionine was administered through drinking water for two weeks. When compared with vehicletreated group, methimazole administration caused a significant (P<0.05) decrease in caudal cold tolerance (CCT) and Body Temperature (BT). Rats administered selenium during day-time showed a significantly higher (P<0.05) plasma glucose and decreased CCT. Nighttime selenium administration to hypothyroid rats resulted in a significant decrease (P<0.05) in plasma glucose. There was an insignificant change in CCT and BT in hypothyroid rats administered selenium in day-time. In conclusion, the study showed that daytime selenium consumption may exert more positive influence on hypothyroidism than nighttime selenium consumption. Selenium is one of elements of the period table. It was discovered by Jons Jacob Belzelius in 1817. It is an essential trace element obtained majorly from foods and water. It functions as a cofactor for enzymes including antioxidant enzymes most especially, glutathione peroxidase and thyroxine-metabolizing enzyme such as 5-iodothyronine deiodinase, catalyzing the conversion of thyroxine to triiodothyronine [1]. Studies have established the link between selenium deficiency and thyroid dysfunctions. For instance, Berry and Larsen [2] and Kohrle [3] reported that selenium depletion in rats resulted in decrease in triodothyronine and increases in tetraiodothyronine and reverse triiodothyronine. Depletion of selenium caused reduction in expression of type I. Selenodeiodinase, a thyroid hormone metabolizing enzyme [4]. Healthy men placed on low selenium diet exhibited high plasma triiodothyronine [5]. In Northern Zaire, selenium supplementation decreased serum tetraiodothyronine, free thyroxine index and reverse triiodothyronine [6]. Works have demonstrated that increased selenium supplementation led to a decrease in antithyroid peroxidase antibodies at three months [7] and a rise in thyrotropin in rat serum [8]. In lactating rats, hypothyroidism induced by methimazole produced hypertrophied thyroid gland and change in body weight [9]. Cerebrum and cerebellum impairments in rats were also reported in an animal model of hypothyroidism induced by methimazole [9]. Other frequently reported clinical manifestations of hypothyroidism include cold, intolerance to cold and changes in glucose metabolism. Investigators have highlighted the influences of selenium supplementation on thyroid functions in states of health and diseases but there is limited information on the diurnal effect of dietary selenium on experimentally-induced hypothyroid symptoms in female wistar rats. Therefore, this study sought to determine the diurnal effect of dietary selenium on methimazole induced hypothyroidism in female rats. Materials and Methods: Site of The Study The experiment was carried out at a research laboratory in conjunction with the Department of Physiology, University of Benin, Benin-city, Edo State. Animal Care and Management Thirty six adult female wistar rats weighing 120-150g were used for the research work. They were divided into six groups consisting of six animals each. These rats were kept in five different cages with a wire mesh covering .They were fed pelletized grower’s mash adlibitum, provided water through drinking trough and kept under 12 hour light and 12 hour darkness at room temperature. Ethical Certification The study was conducted in line with the guidelines of National Institute of Health (NIH) for the use of laboratory rats. Experimental Procedure: The rats were weighed and randomly grouped into; Group A: received distilled water for two weeks and was designated as Vehicle-treated group (VEH). Group B: received 1.35mg/kg of methimazole (P.O.) for two weeks and was designated as hypothyroid group (HYPO). Group C: received 7mg/ml of selenium supplementation in drinking water for two weeks between 6.00am and 6.00 pm and was designated as Day-Time selenium group (DTSE). Group D: received 7mg/ml of selenium supplementation in drinking water for two weeks between 6.00pm and 6.00am and was designated as Night-Time selenium group (NTSE). Group E: received 7mg/ml of selenium supplementation for two weeks between 6.00am and 6.00pm and 1.35mg/kg of methimazole (P.O.) for two weeks and was designated as hypothyroid treated group (HYPO+DTSE). Group F: received 7mg/ml of selenium supplementation for two weeks between 6.00pm and 6.00am and 1.35mg/kg of methimazole (P.O.) for two weeks and was designated as hypothyroid treated group (HYPO+NTSE).
Authors and Affiliations
MJ Adeniyi, FO Agoreyo
Keywords
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- EP ID EP567041
- DOI 10.26717/BJSTR.2017.01.000175
- Views 167
- Downloads 0
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