Auricular acupuncture plays a neuroprotective role in 6-hydroxydopamine-induced Parkinson's disease in rats

Parkinson's disease (PD) is the second-most common neurodegenerative disease. Currently, PD treatment is symptomatic and involves the use of dopamine-based therapies. This study investigated auricular acupuncture on motor and cognitive abilities in rats with 6-OHDA-induced PD. A PD rat model was established by bilaterally injecting 6-OHDA into the lateral dorsal striatum. Then, 2- or 15-Hz auricular electroacupuncture (EA) was applied to the auricular CO15 and CO12 points bilaterally for 20 min three times a week for four consecutive weeks. Both the latency to fall and rest time of the open field test in the EA15 group were greater than in the 6-OHDA group (p < 0.001 and p < 0.05). The time spent on the two-object recognition task was greater in the EA15 group and EA2 group than in the 6-OHDA group (p < 0.01 and p < 0.05). More tyrosine hydroxylase (TH)-positive neurons and fibers were noted in the dorsolateral striatum and substantia nigra (SN) (all p < 0.05). TH expression in the SN was greater in the EA15 group than that in the 6-OHDA group (p < 0.05), while α-synuclein expression in the SN was stronger in the 6-OHDA group than in the EA15 group (p < 0.05). The l-DOPA level in the striatum was higher in the EA15 group than in the 6-OHDA group (p < 0.05). According to the results, rats with 6-OHDA-induced PD may benefit from auricular EA in terms of motor and cognitive behavior as well as neuroprotection.