Brown Adipose Tissue Metabolism in Streptozotocin-Diabetic Rats

Defects of both diet-induced thermogenesis and cold tolerance have been reported for streptozotocin-diabetic rats. Since brown adipose tissue (BAT) is a major effector of both diet- and cold-induced thermogenesis in the rat, the possible cause of these defects was investigated by comparing BAT metabolism under basal conditions and during activation bynerve stimulation, norepinephrine (NE), or octanoate addition i n both streptozotocin-diabetic rats and in controls. The following metabolic indices were measured in rat inter-scapular BAT (IBAT): 1) tissue composition, 2) heat production rate as measured by direct microcalorimetry, 3) redox state of flavoproteins linked to the acyl-coenzyme A dehydrogenase pathway as measured by reflection spectrometry, 4) redox state of NAD (P) as measured by surface-emitted fluorescence, and 5) fatty acid activation and β-oxidation activities in IBAT homogenate. In streptozotocin-diabetic rats, IBAT was atrophied (DNA content unmodified, protein and lipid content decreased...