Up-regulation of apolipoprotein E by leptin in the hypothalamus of mice and rats

Ling Shen, Patrick Tso, David Q.H. Wang, Stephen C. Woods, W. Sean Davidson, Randall Sakai, Min Liu

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Apolipoprotein E (apoE) is a satiation factor, playing an important role in the regulation of food intake and body weight. We previously reported that apoE was present in the hypothalamus, but it is unclear which type of the cells in this brain area expressing apoE. In addition, hypothalamic apoE mRNA levels were significantly reduced in both genetically obese ob/ob (leptin deficient) mice and high-fat diet-induced obese (leptin resistant) rats, raising the possibility that deficient leptin signaling might be related to the change in apoE gene expression. In the present studies, using double-staining immunohistochemistry, we demonstrated that apoE is mainly present in astrocytes. To characterize the effect of leptin on apoE gene expression, ob/ob and db/db mice were treated with recombinant mouse leptin (3 μg/g daily, i.p.) or vehicle for 5 days. We found that the increased hypothalamic apoE mRNA levels occurred only in leptin-treated ob/ob, but not in pair-fed ob/ob, or db/db, mice, indicating that leptin up-regulated hypothalamic apoE gene expression depends upon an intact leptin receptor, and this effect is not related to the changes in food intake and body weight. The reduced apoE gene expression caused by fasting, which also results in relatively lower leptin level, is restored by intracerebroventricular administration of leptin. In addition, leptin was significantly less efficacious in apoE KO mice because these animals consumed more food and lost less weight following leptin treatment, compared with wild-type controls. These observations imply that apoE signaling, at least partially, mediates the inhibitory effects of leptin on feeding.

Original languageEnglish (US)
Pages (from-to)223-228
Number of pages6
JournalPhysiology and Behavior
Volume98
Issue number1-2
DOIs
StatePublished - Aug 4 2009
Externally publishedYes

Keywords

  • Apolipoprotein
  • Food intake
  • Obesity

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience

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