Primary Differences in Lipolysis between Human Omental and Subcutaneous Adipose Tissue Observed Using In Vitro Differentiated Adipocytes

Abstract

Catecholamine-induced lipolysis is elevated in omental as compared to subcutaneous adipocytes due to primary differences between the two cell types (i.e., they have different progenitor cells). Whether there is regional variation in atrial natriuretic peptide (ANP)-induced lipolysis is unknown. We studied whether β-adrenoceptor signaling to lipolysis and ANP-induced lipolysis are involved in the primary differences in lipolysis. In vitro experiments on differentiated preadipocytes from human subcutaneous and omental adipose tissue were performed. The cells were kept in culture for a relative long duration, so any influence of local environment and circulation in the various adipose tissue depots could be excluded. Using β1-, β2-, and β3-adenoceptor agonists, lipolysis was found to be significantly higher in omental as compared to subcutaneous differentiated preadipocytes. Forskolin and dibutyryl cAMP, which act at post-adrenoceptor levels, did not show any regional difference. There was no regional difference in ANP-induced lipolysis. Gene expression of β1- and β3-adrenoceptors was higher and β2-adrenoceptor expression was lower in the omental cells. Omental fat cells have an increased β-adrenoceptor-mediated lipolysis principally due to primary differences in the early event that couples β-adrenoceptor subtypes to G-proteins. ANP-induced lipolysis is not subject to primary regional variation.

visceral - adipocytes - lipolysis - atrial natriuretic peptide - β-adrenoceptors

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