Profound weight loss induces reactive astrogliosis in the arcuate nucleus of obese mice

Mol Metab. 2019 Jun;24:149-155. doi: 10.1016/j.molmet.2019.03.009. Epub 2019 Apr 3.

Abstract

Objective: Obesity has been linked to an inflammation like state in the hypothalamus, mainly characterized by reactive gliosis (RG) of astrocytes and microglia. Here, using two diet models or pharmacological treatment, we assessed the effects of mild and drastic weight loss on RG, in the context of high-fat diet (HFD) induced obesity.

Methods: We subjected HFD-induced obese (DIO) male C57BL/6J mice to a weight loss intervention with a switch to standard chow, calorie restriction (CR), or treatment with the Glp1 receptor agonist Exendin-4 (EX4). The severity of RG was estimated by an ordinal scoring system based on fluorescence intensities of glial fibrillary acidic protein, ionized calcium-binding adapter molecule 1 positive (Iba1), cell numbers, and morphological characteristics.

Results: In contrast to previous reports, DIO mice fed chronically with HFD showed no differences in microglial or astrocytic RG, compared to chow controls. Moreover, mild or profound weight loss had no impact on microglial RG. However, astrocyte RG was increased in CR and EX4 groups compared to chow fed animals and strongly correlated to body weight loss. Profound weight loss by either CR or EX4 was further linked to increased levels of circulating non-esterified free fatty acids.

Conclusions: Overall, our data demonstrate that in a chronically obese state, astrocyte and microglial RG is indifferent from that observed in age-matched chow controls. Nonetheless, profound acute weight loss can induce astrocyte RG in the hypothalamic arcuate nucleus, possibly due to increased circulating NEFAs. This suggests that astrocytes may sense acute changes to both the dietary environment and body weight.

Keywords: Astrocyte; Hypothalamus; Inflammation; Obesity; Reactive gliosis; Weight loss.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Obesity Agents / adverse effects
  • Anti-Obesity Agents / therapeutic use
  • Arcuate Nucleus of Hypothalamus / metabolism*
  • Arcuate Nucleus of Hypothalamus / pathology
  • Astrocytes / metabolism
  • Astrocytes / pathology
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Caloric Restriction / adverse effects
  • Exenatide / adverse effects
  • Exenatide / therapeutic use
  • Glial Fibrillary Acidic Protein / genetics
  • Glial Fibrillary Acidic Protein / metabolism
  • Gliosis / etiology*
  • Gliosis / metabolism
  • Gliosis / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism
  • Obesity / diet therapy
  • Obesity / drug therapy*
  • Weight Loss*

Substances

  • Aif1 protein, mouse
  • Anti-Obesity Agents
  • Calcium-Binding Proteins
  • Glial Fibrillary Acidic Protein
  • Microfilament Proteins
  • Exenatide