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Dopamine D2 receptors regulate leptin and IL‐6 in 3T3 L1 adipocytes (1107.5)
Author(s) -
Cuevas Santiago,
Yang Yu,
Upadhyay Kiran,
Armando Ines,
Jose Pedro
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1107.5
Subject(s) - leptin , medicine , endocrinology , leptin receptor , adipokine , dopamine receptor d2 , chemistry , western blot , adipose tissue , receptor , stimulation , cytokine , biology , obesity , gene , biochemistry
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, P<0.05, ELISA), and decreased IL‐6 protein (‐24.7±5.2%, n=4, P<0.05) and mRNA (0.58±0.01‐fold,n=5,P<0.05) in adipocytes. The D2R‐mediated increase in leptin was prevented by a PI3K inhibitor (LY294002, 10μM, 24h), suggesting that the D2R regulates leptin through the PI3K‐Akt pathway. The effect of the D2R agonist was blunted in adipocytes cultured in insulin‐free media but was restored by the addition of insulin (1μg/ml, 24h). We suggest that the effect of D2R on cytokines and chemokines is tissue‐specific but the mechanism is known. We also studied human adipocytes primary cells culture from subcutaneous and visceral adipocytes tissue; D2R protein was 10‐fold greater in adipocytes from visceral than subcutaneous tissue. Our results suggest that the D2R may play a significant role in the regulation of leptin and IL‐6 expression, especially in visceral adipocytes in the presence of insulin, and may modulate the role adipose tissue in energy homeostasis.