Caprylic acid infusion acts in the liver to decrease food intake in rats

Physiol Behav. 2006 Feb 28;87(2):388-95. doi: 10.1016/j.physbeh.2005.11.004. Epub 2005 Dec 20.


Hepatic portal vein (HPV) infusion of the medium chain fatty acid caprylic acid (CA; 2.3 mg/min, 40 microl/min) for 90 min beginning at dark onset in 18-h food-deprived male rats reduced the size of the first nocturnal meal about 40% (P < 0.01) and reduced 24-h food intake by about 15% (P < 0.001). Identical infusions into the vena cava affected neither initial meal size nor food intake. HPV CA infusion attenuated the postprandial decreases in plasma free fatty acids (P < 0.01) and beta-hydroxybutyrate (P < 0.01). HPV CA infusions did not significantly reduce nocturnal saccharine intake in a two-bottle conditioned taste aversion test, and there was no association between the saccharine intake on the test day and the feeding-inhibitory effect of CA on the conditioning day. HPV CA infusion did not affect plasma concentrations of corticosterone or of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha. HPV CA infusion did not increase plasma concentration of the liver enzyme alanine aminotransferase, but did increase plasma concentration of gamma-glutamyl transferase, although not into the pathophysiological range. These data indicate that CA acts in the liver to produce a signal that inhibits feeding and that this inhibitory effect may be related to increases in hepatic fatty acid oxidation rather than be the result of aversion or toxicity.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • 3-Hydroxybutyric Acid / blood
  • Animals
  • Appetite Depressants*
  • Caprylates / administration & dosage
  • Caprylates / pharmacology*
  • Catheterization, Peripheral
  • Corticosterone / blood
  • Data Interpretation, Statistical
  • Eating / drug effects*
  • Fatty Acids / metabolism
  • Gastric Emptying / drug effects
  • Inflammation / blood
  • Inflammation / metabolism
  • Infusions, Intravenous
  • Interleukin-6 / blood
  • Jugular Veins
  • Ketones / metabolism
  • Liver / drug effects*
  • Male
  • Oxidation-Reduction
  • Portal Vein
  • Rats
  • Rats, Sprague-Dawley
  • Stress, Psychological / metabolism
  • Taste / drug effects
  • Tumor Necrosis Factor-alpha / metabolism
  • Venae Cavae


  • Appetite Depressants
  • Caprylates
  • Fatty Acids
  • Interleukin-6
  • Ketones
  • Tumor Necrosis Factor-alpha
  • octanoic acid
  • 3-Hydroxybutyric Acid
  • Corticosterone