Endocrine Abstracts

Background: Integration between fat tissue, gastrointestinal tract, and the brain has attracted scientific interest in recent years. Thyroid hormones influence carbohydrate mechanisms via its interaction with adipocytokines and gut hormones. Adiponectin, ghrelin and obestatin play important roles in metabolism regulation. TSH receptors have been reported to be present in adipose tissue. Moreover, gut peptides signal to their functional cognate receptors on adipocytes. Nonetheless, the limited number of studies assessing the link between thyroid, gut hormones and adipokines have yielded conflicting results.

Aim: The objective of this study was to examine the associations between adiponectin, ghrelin and obestatin in patients with thyroid dysfunction. Furthermore, there might be a cross talk between them.

Methods: This study was performed on 72 subclinical hypo- and hyperthyroids, and 33 healthy euthyroid subjects. Serum concentrations of adiponectin, ghrelin, obestatin, TSH, free T₃ and free T₄ were measured by ELISA, ECLIA, IRMA and RIA methods.

Results: Serum levels of adiponectin were decreased in hypothyroids and increased in hyperthyroids (11.91±5.02 and 15.13±5.88 ng/ml, respectively) than the controls (12.73±5.19 ng/ml, P<0.05). Ghrelin and obestatin values were lower in hypothyroids (320±81 and 44.3±11.7 ng/l respectively), and higher in hyperthyroids (750±289 and 71.1±27.3ng/l, respectively), compared to the controls (487±110 and 58.5±10.3 ng/l respectively, P<0.05). We found a negative correlation between TSH and adiponectin (r=−0.42, P<0.05). In addition, ghrelin and obestatin showed strong correlations with TSH (r_gr=−0.53, r_ob=−0.59; P<0.001). Also, strong correlations were observed between adiponetin and gut hormones (r_gr=0.75, r_ob=0.69; P<0.001).

Conclusion: Our findings show adiponectin and gut hormones are significantly affected by thyroid dysfunction. Additionally, these hormones are noticeably correlated with each other. Hence, we would like to consider a new regulatory concept, as a novel axis (Pituitary-Fat-Gut axis).