Endocrine disorders and body fat distribution

To evaluate the role of hormones in formation of regional fat distribution, the ratios of visceral fat (V) to subcutaneous fat (S) in the abdomen of rats with various endocrine disorders were determined by computer tomography. Abdominal fat index (AFI), which was obtained by ultrasonography, correlated with V/S. In Cushing's syndrome, seven out of nine patients showed visceral type and V/S ratio positively correlated with cortisol levels. In acromegaly, three out of four patients showed visceral type and V/S ratio correlated not only with growth hormone level, but also with insulin level. All three insulinoma patients showed visceral type. During pregnancy, AFI decreased at the late stage of pregnancy. These results suggest that in visceral fat formation, insulin is the most important factor, and estrogen is an important factor for subcutaneous formation. In vitro experiments showed that visceral fat was much more sensitive to insulin in terms of glucose uptake and triglyceride synthesis than visceral fat. Fibroblast-like cells derived from adipose tissue were cultured. Estrone enhanced cell growth of fibroblast-like cells derived from subcutaneous fat tissue more than that from visceral fat tissue. The results suggested that hyperinsulinism primarily promotes visceral fat tissue enlargement and that estrogen might promote subcutaneous fat tissue enlargement.