Palmitic acid triggers inflammatory responses in N42 cultured hypothalamic cells partially via ceramide synthesis but not via TLR4

Nutr Neurosci. 2020 Apr;23(4):321-334. doi: 10.1080/1028415X.2018.1501533. Epub 2018 Jul 21.


A high-fat diet induces hypothalamic inflammation in rodents which, in turn, contributes to the development of obesity by eliciting both insulin and leptin resistance. However, the mechanism by which long-chain saturated fatty acids trigger inflammation is still contentious. To elucidate this mechanism, the effect of fatty acids on the expression of the pro-inflammatory cytokines IL-6 and TNFα was investigated in the mHypoE-N42 hypothalamic cell line (N42). N42 cells were treated with lauric acid (LA) and palmitic acid (PA). PA challenge was carried out in the presence of either a TLR4 inhibitor, a ceramide synthesis inhibitor (L-cycloserine), oleic acid (OA) or eicosapentaenoic acid (EPA). Intracellular ceramide accumulation was quantified using LC-ESI-MS/MS. PA but not LA upregulated IL-6 and TNFα. L-cycloserine, OA and EPA all counteracted PA-induced intracellular ceramide accumulation leading to a downregulation of IL-6 and TNFα. However, a TLR4 inhibitor failed to inhibit PA-induced upregulation of pro-inflammatory cytokines.In conclusion, PA induced the expression of IL-6 and TNFα in N42 neuronal cells independently of TLR4 but, partially, via ceramide synthesis with OA and EPA being anti-inflammatory by decreasing PA-induced intracellular ceramide build-up. Thus, ceramide accumulation represents one on the mechanisms by which PA induces inflammation in neurons.

Keywords: Ceramide; Fatty acids; Hypothalamic inflammation; Hypothalamic neurons; Toll-like receptor 4.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Cell Line
  • Ceramides / biosynthesis*
  • Encephalitis / chemically induced
  • Encephalitis / metabolism*
  • Hypothalamus / drug effects
  • Hypothalamus / metabolism*
  • Inflammation Mediators / metabolism
  • Neurons / drug effects
  • Neurons / metabolism
  • Palmitic Acid / administration & dosage*
  • Palmitic Acid / metabolism*
  • Rats, Sprague-Dawley
  • Toll-Like Receptor 4 / metabolism*


  • Ceramides
  • Inflammation Mediators
  • Tlr4 protein, rat
  • Toll-Like Receptor 4
  • Palmitic Acid