Adipocyte Leptin Signaling Regulates Glycemia and Cardiovascular Function via Enhancing Brown Adipose Tissue...

While leptin control of metabolism is primarily viewed as centrally mediated, leptin has also been shown to directly regulate adipocyte function. However, the impact of the peripheral effects of leptin on systemic metabolism, especially in the context of obesity, remains unclear. To address this question, we selectively restored adipocyte leptin receptor (LEPR) expression in obese male and female LEPR conditional KO mice. Adipocyte LEPR restoration did not affect body weight but selectively increased brown adipose tissue (BAT) mass in male mice. This was associated with increased energy expenditure, smaller BAT adipocytes, lower triglycerides content, and increased markers of browning and lipolysis exclusively in males. Additionally, adipocyte LEPR restoration enhanced the expression of markers of endothelial cell and angiogenesis in male BAT, supporting increased local vascularization. Improved BAT function in males was also associated with lower HbA1c, better insulin sensitivity, reduced systolic blood pressure, decreased arterial stiffness and improved endothelial function. Lastly, adipocyte LEPR restoration lowered circulating pro-inflammatory cytokines and reduced tissue inflammation in the aorta and the heart, again in males only. These findings reveal a critical role for adipocyte leptin signaling in regulating BAT function and emphasize its importance in maintaining glycemic and cardiovascular health in males with obesity.

Leptin is known to enhance BAT activity through sympathetic stimulation. However, in vitro studies suggest leptin could also act directly on adipocytes to promote lipolysis. Whether these peripheral effects of leptin are relevant to systemic metabolic control, in obesity, remain ill-defined. We addressed this question by selectively restoring leptin receptor (LEPR) in adipocytes of obese LEPR conditional KO mice. LEPR restoration selectively enhanced BAT activity in male mice, which led to improved glycemic control and cardiovascular function. These findings revealed a crucial role for BAT leptin signaling in regulating energy expenditure, glycemic and cardiovascular health, primarily in males.