Background and Objective:The brain α7 nicotinic acetylcholine receptor (α7 nAChR)
has a critical role in the pathophysiology of Major Depressive Disorder (MDD) involving neuroinflammation.
The α7 nAChR stimulation has been shown to modulate the anti-inflammatory effects
of nuclear peroxisome proliferator-activated receptor-α (PPAR-α) via its endogenous ligands in the
brain. The present study determined the effects of α7 nAChR modulator PNU120596 on PPAR-α,
an inhibitor of κB (IκB) and nuclear factor-κB (NF-κB) expression and interleukin-1β (IL-1β)
level in the hippocampus and prefrontal cortex (PFC) in an inflammatory mouse model of MDD
induced by lipopolysaccharide (LPS). We also evaluated the combined effects of PNU120596 and
GW6471, a PPAR-α antagonist, on depressive-like and cognitive deficit-like behaviors in mice.Materials and Methods:Male C57BL/6J mice were treated with PNU120596, followed by systemic
LPS (1 mg/kg, i.p.) administration. The effects of PNU120596 on the mRNA expression of
PPAR-α and IκB were assessed in the hippocampus and PFC using qRT-PCR following LPS administration.
Similarly, the effects of PNU120596 on the immunoreactivity of PPAR-α and NF-κB
were measured in the hippocampus and PFC using an immunofluorescence assay. Furthermore, the
effects of PNU120596 on pro-inflammatory cytokine IL-1β levels were measured in the hippocampus
and PFC using ELISA. The combined effects of PNU120596 and GW6471 were also assessed
against LPS-induced depressive-like and cognitive deficit-like behaviors using the Tail Suspension
Test (TST), Forced Swim Test (FST), and Y-maze test.Results:PNU120596 (4 mg/kg) significantly prevented LPS-induced dysregulation of PPAR-α,
IκB, p-NF-κB p65, and IL-1β in the hippocampus and PFC. Pretreatment with PNU120596 showed
significant antidepressant-like effects by reducing immobility time in the TST and FST. Similarly,
pretreatment with PNU120596 significantly reduced cognitive deficit-like behavior in the Y-maze
test. The antidepressant and pro-cognitive-like effects of PNU120596 were reversed by PPAR-α
antagonist GW6471 (2 mg/kg).Conclusion:These results suggest that PNU120596 prevented LPS-induced MDD and cognitivelike
behavior by regulating α7 nAChR/PPAR-α signaling pathway in the hippocampus and PFC.