Dopamine D2 receptors regulate leptin and IL-6 in 3T3 L1 adipocytes (1107.5)

Leptin, secreted by adipose tissue and regulates energy homeostasis, is a pro-inflammatory cytokine that also regulates the production of other pro-inflammatory factors. Mouse and human adipocytes express dopamine D2 receptors (D2R). We tested the hypothesis that the D2R regulates the expression of leptin and other adipokines/cytokines in adipocytes. Stimulation of the D2R with quinpirole (1μM, 24h) increased leptin (+23±8%, P<0.05,n=4 western blot) in adipocytes and in the media (+78±19%,n=4,P<0.05, ELISA) and IL-6 (+49±7%,n=4,P<0.05, western blot). D2R stimulation also increased, leptin (1.50±0.03-fold,n=5,P<0.05) and IL-6 (2.44±0.08-fold,n=5,P<0.05) gene expression (qRT-PCR). These effects were prevented by a D2R selective antagonist (L741,626, 1μM, 24h). Conversely silencing D2R expression with siRNA decreased the D2R protein (-51.7±9.6%,n=4, P<0.05; western blot) and leptin protein (-51.7±9.6%,n=4 P<0.05) and mRNA (-0.38±0.01-fold,n=5 P<0.05), decreased leptin in the media (-26.2±3.9% pg/mg protein, ...