Increased response to peroxisomal proliferators in starved rats

Area of Science:

• Biochemistry
• Toxicology
• Metabolism

Background:

• Liver peroxisomal beta-oxidation is crucial for fatty acid metabolism.
• Peroxisome proliferator-activated receptors (PPARs) regulate these activities.
• Nutritional status can influence metabolic enzyme responses.

Purpose of the Study:

• To investigate the effect of starvation on the induction of liver peroxisomal beta-oxidation by PPAR agonists.
• To explore the role of carnitine acyltransferase I in this phenomenon.
• To assess the impact of diabetes on peroxisomal responses.

Main Methods:

• Administration of bezafibrate or Wy 14,643 to fed, starved, and streptozotocin-diabetic rats.
• Oral and intraperitoneal administration routes were tested.
• Inhibition of carnitine acyltransferase I was employed.

Main Results:

• Starvation significantly increased the induction of peroxisomal beta-oxidation activities (2-4 fold) compared to fed rats.
• This enhanced response was independent of the administration route.
• Carnitine acyltransferase I inhibitors blocked induction in starved rats but not fed rats.
• Diabetic rats showed no susceptibility to bezafibrate-induced peroxisomal activity.

Conclusions:

• Starvation potentiates the liver's response to peroxisomal proliferators.
• Carnitine acyltransferase I plays a critical role in mediating this starvation-induced enhancement.
• This heightened sensitivity may offer a method for detecting weakly potent xenobiotic peroxisomal proliferators.