Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2005
Publication Date: 4/1/2005
Citation: D'Eon, T.M., Souza, S.C., Greenberg, A.S. 2005. Estrogen regulates lipolysis and perilipin expression by decreasing adiposity and adipocyte size in pairfed ovariectomized mice [abstract]. Journal of Federation of American Societies for Experimental Biology. Paper No. A131.3.
Technical Abstract: Menopause is associated with increased adiposity and greater risk of metabolic disease. Declining estrogen (E2) levels likely contribute to the changes. Animal studies show E2 reduces body fat however it also acts centrally to decrease food intake making it difficult to determine the peripheral effects of E2. We hypothesized that E2 treatment in pairfed ovariectomized (OVX) mice will result in decreased adiposity, higher in vivo lipolysis, smaller adipocytes and increased expression of perilipin, an intracellular lipid-droplet associated protein that regulates lipolysis. C57 Bl6/J mice were ovariectomized and randomized to E2 (OVX-E2) or control (OVX-C) pellets. For 40 days, OVX-C were pairfed to OVX-E2 mice. Results showed that there was no difference in body weight (OVX-C 19.55+/-.86g(SD), OVX-E2 19.15+/-1.04g (SD)). Total adiposity and adipocyte diameter were lower in OVX-E2 mice (OVX-C 0.850+/-0.089g, OVX-E2 0.537g+/-0.083g*; OVX-C 56.7+/-1.2 microm, OVX-E2 49.6+/-2.1microm*, respectively). E2 increased fasting plasma free fatty acids (FFA) (OVX-C 0.288+/-0.018 meq/L, OVXE2 0.501+/-.074 meq/L). Isolated adipocytes from OVX-E2 mice had lower lipolysis in the absence of hormonal stimuli (micromol glycerol /10-6 cells/3hrs) (OVX-C 4.59+/-0.69, OVXE2 1.23+/-0.11**) and higher epinephrine-stimulated lipolysis (OVX-C 40.18+/-1.2, OVX-E2 86.1+/-11.1*). Perilipin expression was higher in OVX-E2 mice (AU/mg protein) (OVX-C 19.2+/-1.2, OVX-E2 53.5+/-9.8*) and was inversely related to adipocyte size (R=-.84**). We concluded that estrogen decreases adiposity by altering peripheral metabolism. Smaller adipocytes and increased perilipin expression result in enhanced physiologic regulation of lipolysis which may facilitate the efflux of fatty acid to peripheral tissues for oxidation. (*p<.05, **p<0.01).