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Impaired adiponectin-AMPK signalling in insulin-sensitive tissues of hypertensive rats

Amaia Rodríguez1, Victoria Catalán, Sara Becerril

  • 1Clínica Universitaria de Navarra, University of Navarra, Pamplona, Spain.

Life Sciences
|September 2, 2008
PubMed
Abstract

Insights

Hypertension in rats leads to increased adiponectin and its receptors, yet impaired downstream signaling causes greater fat accumulation in the liver and muscles. This suggests a defective compensatory mechanism in hypertensive rats.

Area of Science:

  • Endocrinology
  • Metabolic Syndrome
  • Cardiovascular Research

Background:

  • Adiponectin is crucial for improving insulin sensitivity by reducing lipid accumulation.
  • Its role in hypertension, particularly concerning lipid metabolism, requires further investigation.

Purpose of the Study:

  • To investigate alterations in adiponectin signaling pathways in spontaneously hypertensive rats (SHR).
  • To determine the impact of these alterations on lipid accumulation in insulin-sensitive tissues.

Main Methods:

  • Gene and protein expression of adiponectin receptors (AdipoR1, AdipoR2) and related enzymes were analyzed using real-time PCR and Western blot.
  • Intrahepatic and intramyocellular triglyceride levels were quantified enzymatically.
  • Studies were conducted on 10-week-old male spontaneously hypertensive rats (SHR).

Main Results:

  • SHR exhibited overweight, dyslipidemia, glucose intolerance, and insulin resistance.
  • Circulating adiponectin and its expression in fat depots were elevated in SHR.
  • Skeletal muscle showed increased expression of AdipoR1, AdipoR2, ACC, and CPT1, but not in the liver.
  • Despite hyperadiponectinemia, SHR displayed reduced AMPK activation and ACC phosphorylation, leading to increased intrahepatic and intramyocellular lipid accumulation.

Conclusions:

  • Dysregulation of adiponectin downstream effectors contributes to increased triglyceride deposition in SHR.
  • Elevated adiponectin and adiponectin receptors in skeletal muscle may indicate a compensatory mechanism failing to overcome adiponectin resistance in hypertension.

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