Fatty Acid Lingual Application Activates Gustatory and Reward Brain Circuits in the Mouse

Nutrients. 2018 Sep 6;10(9):1246. doi: 10.3390/nu10091246.

Abstract

The origin of spontaneous preference for dietary lipids in humans and rodents is debated, though recent compelling evidence has shown the existence of fat taste that might be considered a sixth taste quality. We investigated the implication of gustatory and reward brain circuits, triggered by linoleic acid (LA), a long-chain fatty acid. The LA was applied onto the circumvallate papillae for 30 min in conscious C57BL/6J mice, and neuronal activation was assessed using c-Fos immunohistochemistry. By using real-time reverse transcription polymerase chain reaction (RT-qPCR), we also studied the expression of mRNA encoding brain-derived neurotrophic factor (BDNF), Zif-268, and Glut-1 in some brain areas of these animals. LA induced a significant increase in c-Fos expression in the nucleus of solitary tract (NST), parabrachial nucleus (PBN), and ventroposterior medialis parvocellularis (VPMPC) of the thalamus, which are the regions known to be activated by gustatory signals. LA also triggered c-Fos expression in the central amygdala and ventral tegmental area (VTA), involved in food reward, in conjunction with emotional traits. Interestingly, we noticed a high expression of BDNF, Zif-268, and Glut-1 mRNA in the arcuate nucleus (Arc) and hippocampus (Hipp), where neuronal activation leads to memory formation. Our study demonstrates that oral lipid taste perception might trigger the activation of canonical gustatory and reward pathways.

Keywords: BDNF; Glut-1; Zif-268; c-Fos; fat taste; gustation; hedonic; linoleic acid.

MeSH terms

  • Animals
  • Behavior, Animal*
  • Brain / metabolism
  • Brain / physiology*
  • Brain-Derived Neurotrophic Factor / genetics
  • Brain-Derived Neurotrophic Factor / metabolism
  • Early Growth Response Protein 1 / genetics
  • Early Growth Response Protein 1 / metabolism
  • Glucose Transporter Type 1 / genetics
  • Glucose Transporter Type 1 / metabolism
  • Linoleic Acid / administration & dosage*
  • Linoleic Acid / metabolism
  • Male
  • Mice, Inbred C57BL
  • Neural Pathways / physiology
  • Neuronal Plasticity
  • Proto-Oncogene Proteins c-fos / metabolism
  • Reward*
  • Taste Buds / metabolism
  • Taste Buds / physiology*
  • Taste Perception*
  • Taste*

Substances

  • Brain-Derived Neurotrophic Factor
  • Early Growth Response Protein 1
  • Egr1 protein, mouse
  • Glucose Transporter Type 1
  • Proto-Oncogene Proteins c-fos
  • Slc2a1 protein, mouse
  • Linoleic Acid