Effects of Meteorin-Like Protein to Rats on Hypothalamus-Pituitary-Thyroid Axisand Peripheral Uncoupling Proteins

Aim: Metrnl secreted from adipose tissue is defined recently discovered peptide hormone. Metrnl in the brain tissue has been determined, its level in serum increases in cold exposure and obesity, causing UCP1 activation in white adipose tissue. This study was conducted to investigate the effects of icv Metrnl application on HHT axis and peripheral UCPs. Material and Method: Forty male Spraque Dawley rats were used in the study. Rats; control was divided sham 10 and 100 nM Metrnl applied group (n = 10). 5µl / hour / 14 days (yBOS in sham group, 10 and 100 nM Metrnl in treatment groups) infusion was performed to the rats except the control group with the osmotic mini pumps. At the end of the experiment, rats were decapitated and blood, hypothalamus, muscle, and white and brown adipose tissue samples were collected. Serum TSH, T3 and T4 levels were determined from the taken blood tissue using ELISA method. The protein levels of TRH from hypothalamus tissue, UCP1 from white and brown adipose tissue; UCP3 from muscle tissue were determined using Western Blot method. Results: It was observed Metrn1 infused intravenously increased serum TSH, T3 and T4 hormone levels compared to the control and sham groups (p <0.05). In addition to, it was found that Metrnl , increased TRH in the hypothalamus, UCP1 in white and brown adipose tissue, UCP3 in muscle tissue (p <0.05). Conclusion: The results of this study show that Metrnl activates peripheral UCPs with hormones plays role in the HHT axis. Key Words: Metrnl, TSH, T3, T4, TRH, UCP1,UCP3