The adipocyte: a secretory and endocrine cell

The concept that adipocytes are secretory cells has emerged over the past few years. Adipocytes synthetize and release a variety of peptide and non-peptide compounds, in addition to their ability to store and mobilize triglycerides, retinoids and cholesterol. These properties allow a cross-talk of white adipose tissue with other organs as well as within adipose tissue. The important finding that adipocytes secrete leptin as the product of ob gene has established adipose tissue as an endocrine organ which communicates with the central nervous system. Tumor necrosis factor-alpha secreted from adipocytes appears as an important component of insulin resistance in adipose tissue by decreasing the insulin receptor-signalling pathway. In vit ro data on the secretion of mitogenic factors (IGF-I and lysophosphatidates) and adipogenic factors (eicosanoids) and their effect on the proliferation and differentiation of preadipocytes to adipocytes suggest in vivo a cross-talk implicated in the hyperplastic development of adipose tissue.