Transient receptor potential V1 modulates neuroinflammation in Parkinson’s disease dementia: Molecular implications for electroacupuncture and rivastigmine

Parkinson’s disease (PD) is a common progressive neurodegeneration disease. Its incidence increases with age and affects about 1% of people over 60. Incidentally, transient receptor potential V1 (TRPV1) and its relation with neuroinflammation in mouse brain has been widely reported. We used 6-hydroxydopamine (6-OHDA) to induce PDD in mice. We then used the Morris water maze and Bio-Plex to test learning and inflammatory mediators in mouse plasma. Western blotting and immunostaining were used to examine TRPV1 pathway in the hippocampus and medial prefrontal cortex (mPFC). On acquisition days 3 (Control = 4.40 ± 0.8 sec, PDD = 9.82 ± 1.52 sec, EA = 5.04 ± 0.58 sec, Riva = 4.75 ± 0.87 sec; P=0.001) and 4, reversal learning days 1, 2, 3 (Control = 2.86 ± 0.46 sec, PDD = 9.80 ± 1.83 sec, EA = 4.6 ± 0.82 sec, Riva = 4.6 ± 1.03 sec; P=0.001) and 4, PDD mice showed significantly longer escape latency than the other three groups. Results showed that several cytokines were up-regulated in PDD mice and reversed by EA and rivastigmine. TRPV1 and downstream molecules were up-regulated in PDD mice and further reversed by EA and rivastigmine. Interestingly, α7 nicotinic receptors and parvalbumin levels in both the hippocampus and prefrontal cortex increased in EA-treated mice, but not in rivastigmine-treated mice. Our results showed that TRPV1 played a role in the modulation of neuroinflammation of PDD, and could potentially be a new target for treatment.