Leptin increases adipose triglyceride lipase in bovine primary adipocytes

Abstract

Proper leptin signaling is critical for energy homeostasis. Although, leptin induces a small but significant increase in lipolysis, mechanisms leading to leptin mediated lipolysis remain unclear. Our objective was to test the hypothesis that leptin alters adipose triglyceride lipase (ATGL) abundance via signal transducer and activator of transcription 3 (STAT3) signaling to regulate lipolysis. Bovine adipocytes were exposed to 0, 10, 100 or 200 ng/mL of bovine leptin for 2 hours to characterize the lipolytic response. Glycerol concentration in the media increased with 100 ng/mL of leptin compared to control adipocytes (P<0.02), but free fatty acid concentrations were similar between control and treated adipocytes (P>;0.80). Total protein abundance and phosphorylation of hormone sensitive lipase and perilipin were similar between control and treated adipocytes (P>;0.05). However, ATGL protein increased with 100 and 200 ng/mL of leptin (P<0.01). Bovine adipocytes were then pre‐treated with 0, 1, 1.25, 1.5, 1.75, or 2 μM of a STAT3 inhibitor, STATTIC, prior to treatment with 100 ng/ml of bovine leptin. Glycerol concentration and ATGL abundance were reduced to control levels with STATTIC concentrations greater than 1 μM. Results from this study suggest that leptin regulates lipolysis via a STAT3 mediated increase in ATGL abundance. Supported by USDA‐CSREES, NRI project 2009–35206–05222.