Influence of Genetic Obesity in Mice on the Lipolytic Response of Isolated Adipocytes to Isoproterenol and ACTH-(1-24)

Abstract

The lipolytic response of isolated adipocytes from genetic obese (C57/BL/6J ob/ob) and lean (C57BL/6J +/? ) mice to ACTH-(1-24), isoproterenol and glucagon has been studied. The mean cell diameter of adipocytes from ob/ob mice was approximately twice that of lean controls. The adipocytes from obese mice contained on the average approximately six times the amount of triacylglycerol present in the smaller lean mouse adipocyte. Lipolysis was calculated both on a per cell basis (10⁵ cells) and per µ mole of triacylglycerol and when expressed on a cell number basis, the larger adipocytes from obese mice showed an ACTH-(1-24) stimulated glycerol release which was quantitatively similar to that of smaller adipocytes from lean mice. When expressed per µ mole of triacylglycerol, the smaller cells from lean animals appeared to be dramatically more responsive to either isoproterenol or ACTH-(1-24). On either basis, ACTH-(1-24) stimulated glycerol release from obese mouse cells was greater than the isoproterenol response. The obese mouse adipocyte showed selective loss of response to isoproterenol compared to its lean control. ACTH-(1-24) = corticotrophin-(1-24)-tetracosadecapeptide