Icariin Reduces Dopaminergic Neuronal Loss and Microglia-Mediated Inflammation in Vivo and in Vitro
Authors: Guo-Qing Wang
Dai-Di Li
Chao Zhang
Shao-Yu Zhou
Jie Liu
Feng Zhang
Di-Sheng Lu
Chun Huang
Journal: Frontiers in molecular neuroscience (2018)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Parkinson’s disease; icariin; microglia; neuroinflammation; neuroprotection.
Affiliations: Joint International Research Laboratory of Ethnomedicine of Ministry of Education and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, China.

Abstract:  Parkinson's disease (PD) is one of the most common neurodegenerative diseases characterized with a gradual loss of midbrain substantia nigra (SN) dopamine (DA) neurons. An excessive evidence demonstrated that microglia-mediated inflammation might be involved in the pathogenesis of PD. Thus, inhibition of neuroinflammation might possess a promising potential for PD treatment. Icariin (ICA), a single active component extracted from the Herba Epimedii, presents amounts of pharmacological properties, such as anti-inflammation, anti-oxidant, and anti-aging. Recent studies show ICA produced neuroprotection against brain dysfunction. However, the mechanisms underlying ICA-exerted neuroprotection are fully illuminated. In the present study, two different neurotoxins of 6-hydroxydopamine (6-OHDA) and lipopolysaccharide (LPS)-induced rat midbrain DA neuronal damage were applied to investigate the neuroprotective effects of ICA. In addition, primary rat midbrain neuron-glia co-cultures were performed to explore the mechanisms underlying ICA-mediated DA neuroprotection. In vitro data showed that ICA protected DA neurons from LPS/6-OHDA-induced DA neuronal damage and inhibited microglia activation and pro-inflammatory factors production via the suppression of nuclear factor-κB (NF-κB) pathway activation. In animal results, ICA significantly reduced microglia activation and significantly attenuated LPS/6-OHDA-induced DA neuronal loss and subsequent animal behavior changes. Together, ICA could protect DA neurons against LPS- and 6-OHDA-induced neurotoxicity both in vivo and in vitro. These actions might be closely associated with the inhibition of microglia-mediated neuroinflammation. 

Retracted: No

PubPeer comments:
 There is image duplication in Figure 3A (see boxed areas in the below). ![file] There is also a duplication between Figure 3A and Figure 4A (see comment below) , 
 here is the marked up image mentioned about Fig 3A v 4A![file] , 
 An additional finding in Figure 2A. Some parts the panels appear to be covered with grey  blobs . In addition, some elements appear to be visible multiple time within the same photo. I marked these with boxes of the same color. There might be more. ![file] , 
 @Asclepias the area is a bit larger... ![file] maybe also the statistics may be checked: control should be 100%, column 4 significance ![file] , 
 The smudged areas are quite remarkable with contrast enhanced. ![file] , 
 We just saw these comments today. First, we appreciate for your concern. We right now carefully re-checked these data and seriously handle this issue. Later, we would explain this issue and make the corresponding corrections. Also, we would contact the editorial office of this joural and deal with this issue. Thank you so much again for your reminder. , 
 Fig 7: The OX-42 panel is duplicated between control and ICA. ![file] , 
 #7 Thank you so much for your concern. Regarding The OX-42 panel duplicated between control and ICA in Figure 7, the similarity was quite higher. However, after we carefully checked and compared the images, these two images indeed came from different samples. Attached file presented the difference between these two groups (marked in yellow ellipsoid).[file] , 
 #8 I agree that there are some small differences between the images, however you have clearly illustrated how closely *similar* they are. Is it more likely that these are different samples or sequential images of the same sample? , 
 #9 Thank you so much for your reminder. Although the background of these two images was almost black, they came from different samples. ,