Alterations in thyroid hormones due to increased intraabdominal pressure in rats

Abstract

Purpose: Although the effects of increased intraabdominal pressure on the abdominal organs are well known, there is a limited data regarding its effects on the thyroid hormones. The aim of this study is to investigate the changes in thyroid hormone profiles during stress endocrine response induced by increased intraabdominal pressure, which was obtained by pneumoperitoneum in rats. Materials and Methods: A hundred-fifty female wistar albino rats were divided into three main groups, according to intraabdominal pressure applied; Control (Group 1), (n:30), low pressure, 15 mmHg, (Groups 2 and 3), (n:60), and high intraabdominal pressure, 25 mmHg, (Groups 4 and 5), (n:60) groups. Groups 2, 3, 4, 5 were divided into three subgroups separately, according to duration of intraabdominal pressure. Rats in Groups 3 and 5 were decompressed at the end of times indicated (15th, 30th, and 45th min) and blood samples were obtained. Whereas blood samples from Groups 2 and 4 were drawn without decompression at the end of times indicated. Measurements included thyroid stimulating hormone, cortisole, vasopressin, adrenocorticotropic hormone, triiodotronin and thyroxin. Result: Our study revealed that blood TSH levels reduce and free T3 and T4 levels increase in case of prolonged intraabdominal pressure increase that cause abdominal compartment syndrome. The change in blood thyroid hormone levels are encountered prominently on 30th and 45th min. Conclusion: Secretion of vasopressin, adrenocorticotropic Hormone and cortisol increases with increasing intraabdominal pressure. At high pressures, thyroid stimulating hormone secretion decreases while the secretion of triiodotronin increases. The effect of this case on the clinical findings has not been fully clarified yet and it needs further studies to clarify underlying mechanism. In this perspective, the findings of this study may be used in further clinical and experimental studies.