title: Mechanisms Involved in Guiding the Preference for Fat Emulsion Differ Depending on the Concentration.
abstract: High-fat foods tend to be palatable and can cause addiction in mice via a reinforcing effect. However, mice showed preference for low fat concentrations that do not elicit a reinforcing effect in a two-bottle choice test with water as the alternative. This behavior indicates the possibility that the mechanism underlying fat palatability may differ depending on the dietary fat content. To address this issue, we examined the influences of the opioid system and olfactory and gustatory transductions on the intake and reinforcing effects of various concentrations of a dietary fat emulsion (Intralipid). We found that the intake and reinforcing effects of fat emulsion were reduced by the administration of an opioid receptor antagonist (naltrexone). Furthermore, the action of naltrexone was only observed at higher concentrations of fat emulsion. The intake and the reinforcing effects of fat emulsion were also reduced by olfactory and glossopharyngeal nerve transections (designated ONX and GLX, respectively). In contrast to naltrexone, the effects of ONX and GLX were mainly observed at lower concentrations of fat emulsion. These results imply that the opioid system seems to have a greater role in determining the palatability of high-fat foods unlike the contribution of olfactory and glossopharyngeal nerves.
authors.affiliation: Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Matsumura
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okafuji
authors.forename: Ai
authors.initials: A
authors.lastname: Eguchi
authors.forename: Shinhye
authors.initials: S
authors.lastname: Lee
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Adachi
authors.forename: Mina
authors.initials: M
authors.lastname: Fujitani
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Inoue
authors.forename: Tohru
authors.initials: T
authors.lastname: Fushiki
mesh_terms: D000818:Animals; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism*; D004655:Emulsions / Q000008:administration & dosage / Q000378:metabolism; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage / Q000378:metabolism; D005518:Food Preferences / Q000502:physiology*; D061287:Glossopharyngeal Nerve Injuries / Q000139:chemically induced; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D061219:Olfactory Nerve Injuries / Q000139:chemically induced; D010743:Phospholipids / Q000008:administration & dosage / Q000378:metabolism; D012054:Reinforcement, Psychology; D013024:Soybean Oil / Q000008:administration & dosage / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D009292:Narcotic Antagonists; D010743:Phospholipids; C545823:soybean oil, phospholipid emulsion; D009271:Naltrexone; D013024:Soybean Oil