A novel tetramethylpyrazine bis-nitrone (TN-2) protects against 6-hydroxyldopamine-induced neurotoxicity via modulation of the NF-κB and the PKCα/PI3-K/Akt pathways

• Published in: Neurochemistry international 2014-12, Vol.78, p.76-85
• Main Authors: Xu, Da-Ping, Zhang, Kun, Zhang, Zai-Jun, Sun, Ye-Wei, Guo, Bao-Jian, Wang, Yu-Qiang, Hoi, Pui-Man, Han, Yi-Fan, Lee, Simon Ming-Yuen
• Format: Article
• Language: English
• Subjects: 6-Hydroxydopamine; Animals; Danio rerio; Male; Neuroinflammation; Neuroprotection; Neuroprotective Agents - pharmacology; NF-kappa B - physiology; Oxidopamine - toxicity; PC12 Cells; Phosphatidylinositol 3-Kinases - physiology; Protein Kinase C-alpha - physiology; Proto-Oncogene Proteins c-akt - physiology; Pyrazines - chemistry; Pyrazines - pharmacology; Rats; Rats, Sprague-Dawley; Signal Transduction - drug effects; Signal Transduction - physiology; Tetramethylpyrazine derivative; Zebrafish
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/j.neuint.2014.09.001

•We synthesized a derivative of natural product tetramethylpyrazine (TMP), namely TN-2.•TN-2 exerted neuroprotection against 6-OHDA induced toxicity in vitro and in vivo.•TN-2 activated PKCα/PI3-K/Akt pathway and suppressed neuroinflammation.•The study implied new potential treatment for Parkinson's disease. The natural product tetramethylpyrazine (TMP) has a variety of biologic activities, including neuroprotection. Nitrones are powerful free radical scavengers. We have designed and synthesized a TMP derivative, TN-2, which is armed with two nitrone moieties. In this study, we investigated the neuroprotective effect of TN-2 against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in vitro and in zebrafish. PC12 cells, zebrafish and rats were exposed to 6-OHDA challenge. MTT assay, LDH release, Hoechst staining, DAF-FM staining, luciferase reporter construct transfection, and western blotting were applied to detect cell viability, apoptosis, intracellular nitric oxide (NO), NF-κB transcriptional activity and proteins expression. In zebrafish, whole-mount staining and real-time PCR were performed to quantify dopaminergic neurons and mRNA expression. Hematoxylin and eosin staining and immunohistochemistry for glial fibrillary acidic protein were used to detect the astrocyte activation in the unilateral 6-OHDA rat model. TN-2 but not TMP exhibited potent neuroprotective effect against 6-OHDA-induced apoptosis in PC12 cells. Moreover, TN-2 prevented dopaminergic neuron loss and suppressed mRNA expression of pro-inflammatory genes, including IL-1β, TNF-α and COX-2, in 6-OHDA-treated zebrafish. TN-2 remarkably attenuated microglial/astrocyte activation in the unilateral 6-OHDA rat model. The mechanistic study demonstrated that TN-2 inhibited over-production of intracellular NO and protein expression of inducible nitric oxide synthase through down-regulating NF-κB activity. Additionally, the PKCα/PI3-K/Akt pathway was also involved in the neuroprotection of TN-2. These results suggest that TN-2 protected against 6-OHDA-induced neurotoxicity via modulating the NF-κB-medicated neuroinflammation and PKCα/PI3-K/Akt pathways.