INTERFERON ALPHA BETA-INDUCED ABNORMALITIES IN ADIPOCYTES OF SUCKLINGMICE/

The modification induced by interferon (IFN) in brown adipose tissue ( BAT) was studied by high spatial resolution magnetic resonance imaging (MRI), histology, and transmission electron microscopy (TEM). In IFN- treated mice, at MRI, the interscapular BAT was slightly enlarged and showed non-homogeneous areas of lipid accumulation. The thickness of t he subcutaneous white adipose tissue was reduced with respect to contr ol mice. In the liver, MRI showed a lipid accumulation. In IFN-treated mice, by light microscopy, brown adipocytes showed a larger lipid dep osit with respect to control mice. At TEM, in BAT, the mitochondria we re reduced in number, smaller and the number of cristae was also signi ficantly reduced with respect to the controls (9.1 +/- 1.5 vs 20.1 +/- 1.9, P < 0.01). The inclusions in the mitochondrial matrix were signi ficantly less numerous in IFN-treated than in control animals (1.9 +/- 0.7 vs 0.9 +/- 0.7 for mitochondrial section, P < 0.01). Abnormalitie s of endoplasmic reticulum described in hepatocytes were not found in brown adipocytes of IFN-treated mice. The present work demonstrates th at, in the BAT of sucking mice, IFN-treatment induces morphologic alte rations and that brown adipocytes have MRI and TEM features resembling those found in the lipid laden BAT of aged animals.