The morphological features and mitochondrial oxidative stress mechanism of the retinal neurons apoptosis in early diabetic rats
Authors: Maonian Zhang
Xiaoyan Li
Huanfen Zhou
Journal: Journal of Diabetes Research (2014)
Discipline: CLINICAL MEDICINE
Keywords: retinal neuron apoptosis; manganese superoxidase dismutase (MnSOD); diabetic retinopathy; Sprague-Dawley rats; TdT-mediated dUTP nick end label (TUNEL)
Affiliations: Department of Ophthalmology, The First Affiliated Hospital of Chinese PLA General Hospital, 51 Fucheng Road, Haidian District, Beijing 100048, China., Department of Ophthalmology, PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing 100853, China.

Abstract:  This paper aims to explore the relationship of retinal neuron apoptosis and manganese superoxidase dismutase (MnSOD) at early phase of diabetic retinopathy. Sprague-Dawley rats were grouped into normal controls and diabetics. Data were collected after 4, 8, and 12 weeks (n = 12). The pathological changes and ultrastructure of the retina, the apoptosis rate of retinal neurons by TdT-mediated dUTP nick end label (TUNEL), mRNA expressions of MnSOD and copper-zinc superoxide dismutase (Cu-Zn SOD), and the activities of total SOD (T-SOD) and subtypes of SOD were tested. For the controls, there was no abnormal structure or apoptosis of retinal neurons at any time. There was no change of structure for rats with diabetes at 4 or 8 weeks, but there was a decrease of retinal ganglion cells (RGCs) number and thinner inner nuclear layer (INL) at 12 weeks. The apoptosis ratio of RGCs was higher than that of the controls at 8 and 12 weeks (P &lt; 0.001). The activity and mRNA levels of MnSOD were lower in diabetics at 4, 8, and 12 weeks (P &lt; 0.05). In summary, the apoptosis of the retinal neurons occurred at 8 weeks after the onset of diabetes. Retinal neuron apoptosis in early diabetic rats may be associated with the decreased activity and mRNA of MnSOD. 

Retracted: No

PubPeer comments:
 Dear Authors, We have read your paper u201cDynamics of Virus-Specific Memory B Cells and Plasmablasts following Viral Infection of the Central Nervous Systemu201d with great interest during our weekly literature meeting. However, as we have spotted a few things that we would have liked to see explained (or corrected) in future publications, we permit ourselves to present some suggestions for improvements: General comments: 1. The overall flow of the text is hard to follow. The paper is well written, but there are certain writing tricks that could make text more accessible. For example: - avoid using too many abbreviations (unless necessary), especially if they are not generally accepted. Recalling abbreviations slows down and disrupts the flow of reading. - create a self-revealing narrative. By doing that, you can make the reader anticipate next results and grasp the readeru2019s attention. It is especially important to provide a smooth connection between paragraphs. - create a schematic summary of the results, which visually depicts your main points. This will help the reader grasp your message. - use words to describe the results instead of numbers (which can easily be found in the figures anyway). - try to be concise and do not elaborate on less important data. Less important data can be placed as supplementary information so it does not divert the attention from the major findings. 2. Providing a scheme of the mouse model and related experiments would additionally help the reader. 3. Showing data as mean with SEM is not wrong, but it is not a really honest way of data presentation either. It would be better for the reader to judge results by seeing all the data points. Presenting medians with range would have been better. 4. Referring to u201cdata not shownu201d is not transparent enough. Such data should have been shown in supplementary files. 5. Y-axis scales should be standardized. When presenting data in %, the scale should, as a default, span from 0-100%, using breaks for smaller values. When presenting other values, it is helpful to use the same scale range between figures panels to facilitate comparison. However, we are aware that sometimes it can be difficult (as in fig. 3 and 5). It might be helpful to use a logarithmic scale, although it may disturb % presentation in fig. 3 and 5. 6. We really like how the authors included both cell number and percentage in one graph (as in fig. 3 and 5). It would be very helpful if data was presented in a similar manner in all of the figures. Especially due to the fact that the paper is based mostly on one kind of data. Similarly, color coding should be consistent throughout the paper. For example, tdTomato+ should always be red and other repetitive distinctions should have their own consistent color-coding. Specific comments: 1. Fig. 1.E u2013 Why is only one column presented as a cumulative? Symbol u201c u201d in the Y-axis title means u201cperu201d or u201cdivided byu201d. We assume that authors meant to use either brackets or u201cxu201d 2. Fig. 2 u2013 tdTomato+ cells are missing CD19+ gating in the name u2013 for example instead of being called tdTomato+ GL7+, they should be called tdTomato+ GL7+ CD19+. 3. Fig. 4 u2013 Why are AID+ cells not staining with B220? It is impossible to tell, if the white arrows are pointing at red-stained cells. It might have been more helpful if all the different channels were also presented as separated images, and not only as a merged one. 4. Fig. 5 u2013 u201cBrainu201d and u201cSpinal cordu201d should have been placed on top of the panel A, as it applies to the whole figure. 5. Is it possible that tdTomato signal spreading in the brain and spinal cord is caused by the viral particles spread and not by cellular migration? 6. Fig. 7 u2013 As only two images are presented, the cluster formation should have been quantified. 7. Fig. 8 u2013 Logarithmic scale on the Y-axis could have been used in order to keep standardized scales between all the graphs. There seems to be a mistake in the figure description: u201cdifferences between the results for wild-type and CD19- - mice are denotedu201d. The comparison is between day 0 and other days, and WT and CD19- - mice were not used in the study. 8. Fig. 9 u2013 The population % presented in the last row of graphs is not consistent between all the samples. All samples should have been shown with GL7+ and IgD-CD138- populations. If the populations were 0%, it still should have been denoted. ,