Kaempferol Regulates Lipid Homeostasis, Endocannabinoid System, and PPARα in Rat Cerebral Cortex Following BCCAO/R

TL;DR

Kaempferol, a dietary flavonoid, reduces brain inflammation in rats by regulating lipid metabolism and anti-inflammatory pathways.

Contribution

This study reveals a dual anti-inflammatory mechanism of kaempferol involving COX-2 inhibition and PPARα activation in a brain hypoperfusion model.

Findings

Kaempferol increased anti-inflammatory N-acylethanolamines and reduced oxidized arachidonic acid metabolites in the frontal cortex.

Kaempferol downregulated COX-2 and 2-AG while upregulating PPARα, CB1R, and CB2R, indicating anti-inflammatory pathway activation.

Plasma levels of DHAEA increased, but PEA and OEA rises were observed only in sham-operated animals, suggesting central redistribution.

Abstract

Previous research has demonstrated that the transient bilateral common carotid artery occlusion and reperfusion (BCCAO/R) effectively models early brain inflammation resulting from sudden hypoperfusion and subsequent reperfusion. According to studies showing that diet and nutrition strongly influence brain neuroplasticity, in this study we evaluated whether kaempferol (KAM), a dietary flavonoid, offers neuroprotection in a rat BCCAO/R model. Adult Wistar rats were gavage fed a single dose of KAM (40 mg) six hours before surgery. Comprehensive lipidomic and molecular analyses were conducted on samples from the frontal and temporal-occipital cortices, as well as the plasma. In the frontal cortex, KAM elevated anti-inflammatory N-acylethanolamines palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and docosahexaenoylethanolamide (DHAEA) and reduced oxidized arachidonic acid metabolites. KAM also downregulated cyclooxygenase- 2 (COX-2) protein and selectively decreased the endocannabinoid 2-arachidonoylglycerol (2-AG), showing a shift in AA metabolism. These molecular changes correlated with increased levels of peroxisome proliferator-activated receptor alpha (PPARα) and cannabinoid receptors CB1R and CB2R, supporting activation of both nuclear and membrane-bound anti-inflammatory pathways. No significant changes were observed in the temporal-occipital cortex. In plasma, DHAEA levels increased similarly to those in the cortex. However, rises in PEA and OEA were detected only in sham-operated KAM-treated animals, suggesting possible central redistribution under hypoperfusion/reperfusion stress. In summary, these findings demonstrate that KAM exerts dual anti-inflammatory effects by inhibiting COX-2-mediated prostanoid synthesis and promoting PPARα-driven lipid signaling. This dual mechanism highlights the potential of KAM as a dietary intervention to reduce neuroinflammation associated with hypoperfusion–reperfusion challenges.

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