Hepatic-portal oleic acid inhibits feeding more potently than hepatic-portal caprylic acid in rats.
In several human and animal studies, medium-chain triglycerides decreased food intake more than did long-chain triglycerides. It is possible that faster uptake and metabolism of medium-chain fatty acids in the liver is responsible for this difference. To test this hypothesis we compared the feeding effects of hepatic portal vein (HPV) infusion of the medium-chain fatty acid caprylic acid (CA) with those of the long-chain fatty acid oleic acid (OA). Contrary to our expectation, six-h HPV infusion of 14 microg/min (50 nmol/min) OA robustly inhibited feeding, whereas infusion of 22 or 220 microg/min (150 and 1500 nmol/min) CA failed to have any effect on feeding. Only a much larger dose of CA, 1100 microg/min (7500 nmol/min) inhibited feeding similarly to 14 microg/min OA. The increased feeding-inhibitory potency of OA did not appear to be due to differences in stimulation of hepatic fatty acid oxidation because equimolar (50 nmol/min) doses of OA (14 microg/min) and CA (7 microg/min) did not differentially affect post-infusion levels of beta-hydroxybutyrate. Stress, inflammation, acute hepatotoxicity or oxidative stress also do not appear to account for the increased feeding-inhibitory potency of HPV OA because plasma concentrations of the stress hormones corticosterone and epinephrine, the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha, the liver enzymes gamma-glutamyl transferase and alanine aminotransferase and as well as hepatic levels of malondialdehyde and glutathione were all similar after HPV infusion of saline or of 50 nmol/min OA or CA.
Jambor de Sousa
Ulrike L
UL
Institute of Animal Sciences, ETH Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
Benthem
Lambertus
L
Arsenijevic
Denis
D
Scheurink
Anton J W
AJ
Langhans
Wolfgang
W
Geary
Nori
N
Leonhardt
Monika
M
D000818:Animals; D001067:Appetite Depressants / Q000008:administration & dosage*; D001522:Behavior, Animal; D002210:Caprylates / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005978:Glutathione / Q000378:metabolism; D008099:Liver; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D019301:Oleic Acid / Q000008:administration & dosage*; D011169:Portal Vein / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D001067:Appetite Depressants; D002210:Caprylates; D019301:Oleic Acid; D008315:Malondialdehyde; D005978:Glutathione; C031492:octanoic acid