Cardiovascular findings and effects of caffeine in experimental hypothyroidism

Thyroid hormones are necessary for the normal functioning of many organs. The deficiencies and excesses of these hormones cause the functions of organs and systems to deteriorate. It is reported that the cardiovascular system is also affected by thyroid hormone disorders. However, studies in this area are very limited. Hypothyroidism is a common problem that affects both humans and animals. The aim of this study is to examine the cardiovascular findings that may occur with propylthiouracil (PTU) in rats with hypothyroidism and to evaluate the effect of caffeine. To examine pathologically the effect of caffeine on heart, thyroid and blood parameters in these hypothyroid rats. In the study, a total of 40 female Wistar albino rats weighing 250-300 grams were used and the rats were divided into 4 groups of 10 animals and the study was completed in 2 months. Group 1 (Control group) they were fed with normal water for 2 months as adlibitum. Group 2 (PTU induced hypothyroidism group) was administered with 10 mg / kg / day intraperitoneal injection for 2 months. Group 3 administered PTU (10mg / kg / day) intraperitoneal injection for 1 month and induced hypothyroidism, then caffeine (10 mg / kg / day) was mixed with water and given by gavage for an additional 1 month. Group 4 caffeine (10 mg / kg / day) was mixed with water and given by gavage throughout the study period (2 months). At the end of the study, the rats were decapitated under anesthesia and thyroid and heart samples were collected for histopathological examination. Blood was taken and plasma was removed for TSH, T3 and T4 analyzes. During necropsy, it was noticed that thyroid grew significantly in the group given PTU and the thyroids of the rats in the other group were normal. Heart samples were normal in all groups. In plasma samples, an increase in TSH level and a decrease in T3 and T4 levels were observed in Group 2. Hormone levels of other groups were normal. In histopathological examination, prominent proliferations were noted in thyroid epithelium in the PTU group. Hyperemia was observed in the PTU group in the histopathological examination of the heart tissues. Heart samples were evaluated immunohistochemically for troponin. It showed that troponin expressions were slightly decreased in the myocardium of rats in Group 2, and that caffeine administration for 4 weeks after the PTU was discontinued may contribute to the correction of troponin expressions. The results of this study showed that caffeine administration after the cessation of PTU administration in rats with experimental hypothyroidism can help correct changes in both thyroid and heart. Furthere studies should be conducted to investigate caffeine administration at different doses and durations on this subject.