The effects of Leptin and Adiponectin on Pdx1, Foxm1, and PPARγ Transcription in Rat Islets of Langerhans

BACKGROUND: Leptin and adiponectin are two hormones, which are released from adipocytes in order to control energy expenditure. Both hormones are also involved in glucose homeostasis through control of insulin secretion from pancreatic islets. Since Pdx1, PPARγ, and foxm1 play important roles in islets function, it is essential to understand how these genes are regulated in the islets of Langerhans. OBJECTIVES: We have designed an experiment to identify the effect of leptin and adiponectin treatment on Pdx1, PPARγ, and foxm1 transcription. MATERIALS AND METHODS: Islets were isolated from adult male rats by collagenase and incubated with different concentrations of leptin and adiponectin for 24 hours. Next, by means of real time PCR, we evaluated the gene transcription related to a housekeeping gene. The effect of leptin and adiponectin on insulin secretion was evaluated by ELISA. RESULTS: Leptin decreased PPARγ transcription and insulin secretion, while adiponectin significantly increased Pdx1 and PPARγ transcription and insulin secretion in rat islets. The transcription of foxm1 did not change in the islet cells treated with leptin or adiponectin. CONCLUSIONS: These findings indicate the possibility that Pdx1 and PPARγ transcription is a mediator of leptin and adiponectin function in control of insulin secretion and glucose homeostasis in pancreatic islets.