نقش پپتيدهاي اپيوئيدي در ميانجي گري اثرگرلين بر هورمون‌هاي تيروئيدي موش صحرايي

Opioid peptides role in mediating Ghrelin effect on thyroid hormones secretion in Rats

Recent studies suggested that Ghrelin have important role on various metabolic functions, particularly regulation of thyroid hormones secretion and it results in reduction of thyroid hormones level. Other studies revealed that endogenous opioids have similar effect on T3 and T4 secretions. This study was undertaken to determine the mediating effect of endogenous opioids on ghrelin metabolic pathway and thyroid secretions. For this purpose, male Wistar rats divided into four groups: Normal Saline (control group), Ghrelin (12nmol/kg, ICV), Naloxone and finally Naloxone + Ghrelin. l.C.V injection of drugs was taken for three days and blood samples were collected 30 minutes before and 2 hours after injection. The average contents of T3 and T4 in plasma were measured using the radioimmunoassay methods. Results showed that l.C.V injection of Ghrelin reduce T3, but have no significant effect on T4 level in plasma. T3 and T4 level in plasma were not significantly altered after l.C.V administration of Naloxone. Pretreatment with both Naloxone and Ghrelin can not affected T3 and T4 concentration in plasma. This data provide evidence that opioids have a role in mediating Ghrelin effect on thyroid hormones secretion.