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Ciliary neurotrophic factor suppresses hypothalamic AMP-kinase signaling in leptin-resistant obese mice

Gregory R Steinberg1, Matthew J Watt, Barbara C Fam

  • 1St. Vincent's Institute, 9 Princes Street, Fitzroy, Victoria 3065, Australia. gsteinberg@svi.edu.au

Endocrinology
|May 6, 2006
PubMed

Insights

Ciliary neurotrophic factor analog (CNTF(Ax15)) reduces food intake by decreasing hypothalamic AMP-activated protein kinase (AMPK) activity. This effect bypasses diet-induced leptin resistance in obese mice.

Area of Science:

  • Neuroscience
  • Metabolism
  • Endocrinology

Background:

  • Leptin is a key regulator of food intake, but its effectiveness is compromised in diet-induced obesity due to leptin resistance.
  • AMP-activated protein kinase (AMPK) is a critical signaling molecule involved in regulating energy balance and food consumption.
  • Ciliary neurotrophic factor (CNTF) analogs represent a potential therapeutic strategy for obesity.

Purpose of the Study:

  • To investigate the effects of a second-generation CNTF analog, CNTF(Ax15), on AMPK signaling and food intake.
  • To compare the efficacy of CNTF(Ax15) and leptin in reducing food intake and modulating AMPK activity in diet-induced obesity models.
  • To determine if CNTF(Ax15) can overcome leptin resistance.

Main Methods:

  • Administration of CNTF(Ax15) via intraperitoneal injection and intracerebroventricular infusion in rodents.
  • Measurement of hypothalamic AMPKalpha2 activity, phosphorylation of AMPKalpha2Thr172, and acetyl-CoA carboxylase phosphorylation.
  • Assessment of food intake and signaling pathways (STAT3 phosphorylation, AMPK signaling) in specific brain regions (ARC, PVN) in control and high-fat diet-fed mice.

Main Results:

  • Acute CNTF(Ax15) injection reduced hypothalamic AMPK activity and phosphorylation.
  • Central CNTF(Ax15) administration reduced food intake and hypothalamic AMPK signaling, specifically in the arcuate nucleus.
  • In diet-induced obesity, CNTF(Ax15) reduced food intake and hypothalamic AMPK activity in both control and high-fat diet-fed mice, whereas leptin lost efficacy.
  • CNTF(Ax15) effects on AMPK signaling in the ARC and PVN were not blunted by a high-fat diet, unlike leptin's effects.

Conclusions:

  • CNTF(Ax15) effectively reduces food intake and hypothalamic AMPK activity.
  • CNTF(Ax15) bypasses diet-induced leptin resistance, suggesting its potential as an anti-obesity therapeutic.
  • Targeting hypothalamic AMPK signaling with CNTF analogs offers a promising strategy for managing obesity, even in the presence of leptin resistance.

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