RETRACTED: Icariin Reduces Dopaminergic Neuronal Loss and Microglia-Mediated Inflammation in Vivo and in Vitro

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.

Combination Treatment of Icariin and L-DOPA Against 6-OHDA-Lesioned Dopamine Neurotoxicity

“…Recent studies demonstrate ICA evoked neuroprotection against brain ischemic injury and neurodegenerative diseases (Xiao et al, 2016 ). In our previous work, ICA attenuated DA neuronal damage and microglia-induced neuroinflammation both in vivo and in vitro (Wang et al, 2018 ). Besides, ICA showed synergistic effects combined with methylprednisolone to attenuate experimental autoimmune encephalomyelitis (EAE) through enhancing anti-apoptotic actions (Wei et al, 2015 ).…”

“…It has been evaluated that ICA protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced DA neuronal damage through the regulation of phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MEK) signaling pathway (Chen et al, 2017 ). Our previous study found that ICA attenuated 6-OHDA and lipopolysaccharide (LPS)-induced DA neuronal death and thereby improved motor dysfunction (Wang et al, 2018 ). In this study, ICA enhanced L-DOPA-mediated DA neuroprotection and ameliorated L-DOPA-induced motor dysfunction without interfering with the therapeutic efficacy of L-DOPA, suggesting that the use of the potential neuroprotective agent in combination with available drugs might serve as promising therapeutic potential for PD treatment.…”

Icariin Protects Hippocampal Neurons From Endoplasmic Reticulum Stress and NF-κB Mediated Apoptosis in Fetal Rat Hippocampal Neurons and Asthma Rats

“…Icariin is a major bioactive monomer belonging to flavonoid glycosides attracted from Epimedium, being a classic tonic agent in traditional Chinese medicine. More pharmacological studies indicating that icariin possesses various therapeutic capabilities, especially for neuro-protective (Wang et al, 2017), cardio-protective (Ke et al, 2015), anti-FIGURE 6 | Icariin decreased airway hyperresponsiveness (AHR) to elevating doses of methacholine (Mch) by decreasing airway resistance (RL) and increasing dynamic compliance (Cdyn) in asthmatic rats. The diagram illustrated changes of RL (A) and Cdyn (B) among different groups.…”

Icariin-Functionalized Nanodiamonds to Enhance Osteogenic Capacity In Vitro

“…Horny goat weed, also known as Epimedii herba or Ying Yang Huo , is extensively used to treat various diseases, including heart disease, osteoporosis, and rheumatism [ 16 , 17 ]. Icariin (ICA), one of the pharmacologically dynamic ingredients extracted from horny goat weed, possesses various therapeutic abilities, including neuroprotective, cardioprotective, anti-inflammatory, and anticancer actions [ 18 , 19 , 20 ]. Researchers have also shown an interest in the osteoinductive effects of ICA for bone tissue regeneration and the treatment of postmenopausal osteoporosis.…”