Cellular and Molecular Characterization of the Adipose Phenotype of the Aromatase-Deficient Mouse

• DOI: 10.1210/en.2002-221123
• Publication Date: 2003-03-15T13:56:18Z
• Authors: Marie L. Misso; Yoko Murata; Wah Chin Boon; Margaret E. E. Jones; Kara L. Britt; Evan R. Simpson
• Keywords: Leptin; Male; Mice, Knockout; 2. Zero hunger; 0301 basic medicine; 0303 health sciences; Estradiol; Lipolysis; Fatty Acids; Gene Expression; Cell Count; Lipid Metabolism; DNA-Binding Proteins; Lipoprotein Lipase; Mice; 03 medical and health sciences; Aromatase; Adipose Tissue; Adipocytes; CCAAT-Enhancer-Binding Proteins; Animals; Female; Fatty Acid Synthases; Cell Size

Estrogen deficiency in the aromatase knockout (ArKO) mouse leads to the development of obesity by as early as 3 months of age, which is characterized by a marked increase in the weights of gonadal and infrarenal fat pads. Humans with natural mutations of the aromatase gene also develop a metabolic syndrome. In the present study cellular and molecular parameters were investigated in gonadal adipose tissue from 10-wk-old wild-type (WT) and ArKO female mice treated with 17beta-estradiol or placebo to identify the basis for the increase in intraabdominal obesity. Stereological examination revealed that adipocytes isolated from ArKO mice were significantly larger and more abundant than adipocytes isolated from WT mice. Upon treatment with estrogen, the volume of these adipocytes was greatly reduced, whereas the reduction in the number of adipocytes was much less pronounced. Transcriptional analysis using real-time PCR revealed concomitant changes with adipocyte volume in the levels of transcripts encoding leptin and lipoprotein lipase, whereas peroxisome proliferator-activated receptor gamma levels followed a pattern closer to that of adipocyte number. Little change was observed in levels of transcripts for factors involved in de novo fatty acid synthesis, beta-oxidation, and lipolysis, suggesting that changes in the uptake of lipids from the circulation are the main mechanisms by which estrogen regulates lipid metabolism in these mice.