Cold Exposure Differentially Stimulates Angiogenesis in BAT and WAT of Mice: Implication in Adrenergic Activation

BACKGROUND/AIMS: To characterize the temporal profile of cold-induced angiogenesis in brown and white adipose tissues of mice in vivo and the temporal changes of angiogenic factors in primary mice brown (BA) and white adipocytes (WA) treated with β3-adrenoceptor agonist (CL316,243) in vitro. METHODS: 8-week old male C57BL/6J mice were individually housed in conventional cages under cold exposure (4°C) for 1, 2, 3, 4 and 5 days. Interscapular brown adipose tissue (iBAT), inguinal subcutaneous (sWAT) and epididymal white adipose tissues (eWAT) were harvested for immunohistochemical and gene expression analysis. In vitro, primary mice BA and WA treated with or without CL316,243 were harvested for gene expression and protein secretion analysis. RESULTS: A combination of morphological and genetic (Vegfa, Vegfr2, Hif-1α, Pai1 and Pedf) analyses demonstrated depot-specific angiogenesis in response to cold exposure. Upon CL316,243 treatment, angiogenic factors (Vegfa, Vegfr2, Hif-1α, Pai1 and Pedf) and secreted protein VEGFA were transiently increased in both BA and WA. CONCLUSION: Our results show that iBAT is highly responsive to cold-induced angiogenesis that is mainly supported by sWAT with a lesser extent by eWAT. Moreover, the angiogenesis is a transient process with the angiogenic factors may work in an autocrine/paracrine manner.