Neuroprotective effect of phosphocreatine on oxidative stress and mitochondrial dysfunction induced apoptosis in vitro and in vivo: Involvement of dual PI3K/Akt and Nrf2/HO-1 pathways
Authors: Yanlin Song
Xiaodong Ma
Hailong Li
Bin Sun
Zhongyuan Tang
Mengyue Niu
Min Hu
Zeyao Tang
Guozhu Han
Peng Chu
Jinyong Peng
Abdullah Shopit
Eskandar Qaed
Ying Yang
Journal: Free Radical Biology and Medicine (2018)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: Mitochondrial respiration; Neuroprotection; Oxidative stress; Phosphocreatine.
Affiliations: Department of Pharmacology, Dalian Medical University, Dalian, Liaoning 116044, PR China., Department of Orthodontics, School of Stomatology, Jilin University, 1500 Qinghua Road, Changchun 130021, PR China., Dalian Medical University, Affiliated Hosp 2, Neurological Intensive Care Un¬†it, Dalian 116027, PR China., Department of Orthodontics, School of Stomatology, Jilin University, 1500 Qinghua Road, Changchun 130021, PR China. Electronic address: ., Department of Pharmacology, Dalian Medical University, Dalian, Liaoning 116044, PR China. Electronic address: .

Abstract:  Methylglyoxal (MGO), an active metabolite of glucose, is observed in high levels in the tissues and blood of diabetic patients. Phosphocreatine (PCr), a high-energy phosphate compound, exhibits a range of pharmacological actions but little is well known of its neuroprotective action. The aim of the present study was to investigate the neuroprotective effects and the possible mechanisms of PCr. Diabetes is closely associated with neurodegenerative diseases, leading not only to the peripheral nervous system (PNS) and but also to central nervous system (CNS) damage. Therefore, we established two rat models of diabetes in vivo induced by MGO and streptozocin (STZ) respectively, while utilized differentiated PC-12 cells in vitro. Treatment of PC-12 cells with PCr markedly attenuated MGO-induced change of viability, apoptosis, accompanied by decreased levels of caspase-3, casapse-9 and Bcl-2/Bax protein ratio. Determination of cellular respiratory function was performed with intact PC-12 cells and homogenized hippocampal neuron tissue of rat. Reactive oxygen species (ROS) generation was assessed by membrane permeable fluorescent probe DCFH-DA. The expressions of Akt, Nrf2 and HO-1 were examined by Western blot. PCr pretreatment significantly reduced oxidative stress-induced high LDH, MDA level, and ROS production of PC-12 cells. PCr pretreatment also significantly decreased mitochondrial dysfunction in vitro and in vivo. In addition, PCr pretreatment increased the expression of p-Akt, Nrf2 and HO-1, and reduced the apoptosis. Moreover, the expression of Cleaved caspase3 was partially increased and the p-Akt, Nrf2 and HO-1 was partially reduced by a PI3K inhibitor (LY294002). While, compared with LY294002 groups, pre-treatment with PCr at the concentrations of 20 mM significantly reduced the expression of Cleaved caspase3 and increased the expression of p-Akt, Nrf2 and HO-1. Molecular docking assay showed that PCr possessed powerful affinity towards to Akt with lower binding energy. In conclusion, the neuroprotective effects of PCr in vitro and in vivo rely on normalizing mitochondrial function and reducing oxidative stress via Akt mediated Nrf2/HO-1 pathway, suggesting that PCr may be a novel therapeutic candidate for the treatment of diabetes-associated neurodegenerative diseases. 

Retracted: No

PubPeer comments:
 Fig. 6A, Fig. 6D and Fig. 7B. Two sets of WB bands appear more similar than expected.  , 
 #1 Thank you very much for your correction. We rechecked the original data and found that there was indeed an inadvertence error in clipping, but this error would not affect the correctness of the results of our paper. We have contacted the editorial department to request correction of this error. We apologise for these errors and any inconvenience this may have caused. , 
 Could the authors please provide the update about the correcrion? , 
 #3  This is the modified Fig.6A and Fig.6D.We have filled in the errata template provided by the magazine and sent it back to the magazine , 
 #3 Thank you very much for point out the mistake. After self - examination, the journal agreed to our corrigendum publication. The email is as follows. Dear Dr. Li, Thank you for checking with me. The Editor-in-chief has approved the corrigendum and we will be sending the typeset proofs to you soon. Please let me know if I can be of any further assistance. Kind regards, Rajashri Ravindranathan Journal Manager Tel: +91 44 42994880 , 
 #5 Could the authors please post the original scans? , 
 #5 Thank you for your reply, and the effort to correct the scientific records. , 
 #6 The original scan is shown below   , 
 #1 The HO-1 band identified in blue from Figure 6A also appears unexpectedly similar to the P-Akt band for the Rat2 gel. The last lane appears different, although the shape and position is also similar. Could the authors please post the original scans for these as well? ***  , 
 #8 If I understand correctly, the scans posted in #8 show (in order): the HO-1 scan from A (posted in #4), and the Beta-Actin plot in D (posted in #4). When looking at the second figure posted in #8, I can t see any noise in the plot aside from a small fraction on the edge of the blot, has the image been modified to remove the noise in some way? ,