Estradiol may limit lipid oxidation via Cpt 1 expression and hormonal mechanisms.

Academic Article

Abstract

  • OBJECTIVE: Evidence indicates that estrogen depresses hepatic lipid oxidation. We tested the hypothesis that estradiol (E(2)) treatment depresses transcription of carnitine palmitoyltransferase-1 (Cpt 1) mRNA and increases adiposity. RESEARCH METHODS AND PROCEDURES: Six ovariectomized female rats were given a subcutaneous pellet of E(2) (5 mg/d), and six were given placebo. Rats were pair-fed by group for 18 days. Body composition was assessed chemically: mRNA for liver Cpt 1, adipose tissue uncoupling protein-2 (Ucp 2), and quadriceps Ucp 3 by Northern analysis; serum glucose, triglycerides (TGs), and free fatty acids by standard techniques; and serum insulin and glucagon by radioimmunoassay. RESULTS: E(2)-treated rats lost more weight than placebo-treated rats (37.3 +/- 6.0 vs. 16.2 +/- 2.6 g, p < 0.01), but did not differ in final carcass composition (adjusted for eviscerated body mass). E(2)-treated rats had lower liver Cpt 1 (p < 0.001) and skeletal muscle Ucp 3 (p < 0.05) mRNA and lower concentrations of glucose, glucagon, and free fatty acids (p < 0.05). E(2)-treated rats tended to have higher insulin (p = -0.067) and TG (p = 0.097). TG tended to be correlated with Cpt 1 mRNA (r = -0.56 and p = 0.07). DISCUSSION: These results suggest that, although E(2) is likely to suppress lipid oxidation and promote TG synthesis, these effects are not manifested in a relative increase in carcass adiposity after 18 days of treatment, at least under conditions of negative energy balance. The possible role of E(2)-mediated changes in insulin and glucagon secretion on hepatic substrate metabolism warrants further study.
  • Published In

  • Obesity Research  Journal
  • Keywords

  • Animals, Blotting, Northern, Body Composition, Carnitine O-Palmitoyltransferase, Carrier Proteins, Eating, Estradiol, Female, Glucagon, Insulin, Ion Channels, Lipid Metabolism, Membrane Proteins, Mitochondrial Proteins, Oxidation-Reduction, RNA, Messenger, Rats, Rats, Wistar, Triglycerides, Uncoupling Protein 1
  • Digital Object Identifier (doi)

    Pubmed Id

  • 23506716
  • Author List

  • Gower BA; Nagy TR; Blaylock ML; Wang C; Nyman L
  • Start Page

  • 167
  • End Page

  • 172
  • Volume

  • 10
  • Issue

  • 3