Transient effect of melatonin treatment after neonatal hypoxic-ischemic brain injury in rats

Hester Rijkje Berger; Axel K. G. Nyman; Tora Sund Morken; Marius Widerøe

doi:10.1371/journal.pone.0225788

Peer Review History

Original SubmissionJune 14, 2019
11 Aug 2019 Decision Letter - Olivier Baud, Editor PONE-D-19-16889 Transient effect of melatonin treatment after neonatal hypoxic-ischemic brain injury in rats PLOS ONE Dear Dr. Widerøe, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. We would appreciate receiving your revised manuscript by Sep 25 2019 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. 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Or, if the data are not a core part of the research being presented in your study, we ask that you remove the phrase that refers to these data. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? 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Reviewer #1: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: Berger et al. describe the effects of melatonin (MEL) treatment in a model of hypoxia-ischemia (HI) in the P7 rat. While this is an interesting research topic (considering the safety of the molecule and clinical settings) we feel that the manuscript need several improvements before it can be accepted. - In the introduction consider more recent works on melatonin in clinical settings: Biran et al. 2019 Int J mol Sci; Colella et al., 2016, Early Hum Dev 102: 1-3; Biran et al., 2014, 56: 717-723. - Again, in the discussion, consider several papers reporting that MEL promotes myelination with oligodendroglial maturation (Olivier et al., PlosOne 2009, 4, e7128) and decreases white matter inflammation (Villapol et al., Ped Res 2011, 69:51-55) in neonatal rats after cerebral injury. - As in your study you also shown that HI induced demyelination, it could has been interesting to measure the thickness of myelin (in the corpus callosum) in the 3 groups of animals, and to evaluate whether MEL was associated to an increase in the density of mature oligodendrocytes. - WM injury is the underlying cause of motor and cognitive disability in injuried babies that suffer HI and/or ischemia. Evaluation of sensorimotor performance and motor coordination by using the pole test could have been a good test to see (or not) an effect of MEL on HI (namely in mild injured animals). - Concerning no sex-difference in this study allows to concider MEL as a broad spectrum treatment. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: Yes: Christiane CHARRIAUT-MARLANGUE [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0225788.r001
Revision 1
24 Oct 2019 Author Response Response to reviewers We would like to thank the reviewers for their time spent reviewing the manuscript and for their valuable comments. We have responded to all issues and questions raised the by the editor and reviewer and made necessary changes to the manuscript and figures to accommodate your critique. See specific answers to each point raised below. Journal Requirements: Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. We have gone over the manuscript and made sure it complies with the PLOS style requirements. 1. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. The data has been deposited in the repository and the DOI is provided in the cover letter. 2. We note that you have included the phrase “data not shown” in your manuscript. Unfortunately, this does not meet our data sharing requirements. PLOS does not permit references to inaccessible data. We require that authors provide all relevant data within the paper, Supporting Information files, or in an acceptable, public repository. Please add a citation to support this phrase or upload the data that corresponds with these findings to a stable repository (such as Figshare or Dryad) and provide and URLs, DOIs, or accession numbers that may be used to access these data. Or, if the data are not a core part of the research being presented in your study, we ask that you remove the phrase that refers to these data. We have now included the data in a supplementary table (S2 Table) and included a reference to that in the manuscript. Reviewer #1: Berger et al. describe the effects of melatonin (MEL) treatment in a model of hypoxia-ischemia (HI) in the P7 rat. While this is an interesting research topic (considering the safety of the molecule and clinical settings) we feel that the manuscript need several improvements before it can be accepted. - In the introduction consider more recent works on melatonin in clinical settings: Biran et al. 2019 Int J mol Sci; Colella et al., 2016, Early Hum Dev 102: 1-3; Biran et al., 2014, 56: 717-723. Thank you for this comment. References to the suggested work has been included in the introduction section in the manuscript. - Again, in the discussion, consider several papers reporting that MEL promotes myelination with oligodendroglial maturation (Olivier et al., PlosOne 2009, 4, e7128) and decreases white matter inflammation (Villapol et al., Ped Res 2011, 69:51-55) in neonatal rats after cerebral injury. Thank you for bringing our attention to these papers. A reference to Villapol et al has been added to the discussion regarding short term effects. The study by Olivier et al provides compelling evidence of mechanisms of melatoninergic neuroprotection. We feel, however, that the choice of animal model (e17 uterine artery ligation) makes the result more relevant to a slightly different clinical problem (diffuse white matter injury in very preterm infants) than we attempt to address (perinatal hypoxia-ischemia). - As in your study you also shown that HI induced demyelination, it could has been interesting to measure the thickness of myelin (in the corpus callosum) in the 3 groups of animals, and to evaluate whether MEL was associated to an increase in the density of mature oligodendrocytes. Thank you for this suggestion. We have now included the measurements of corpus callosum in all three groups in the results (Figure 4, and results section under white mater injury development in cc) and commented on this in the discussion. The results indicate a slight tendency towards better preservation of the cc among MEL animals, but the difference was not near statistical significance and cc thickness was foremost correlated with the overall brain injury. Unfortunately, we are not able to perform further immunohistochemistry to investigate further the oligodendrocyte density and maturity. - WM injury is the underlying cause of motor and cognitive disability in injuried babies that suffer HI and/or ischemia. Evaluation of sensorimotor performance and motor coordination by using the pole test could have been a good test to see (or not) an effect of MEL on HI (namely in mild injured animals). Thank you for this suggestion. We chose to evaluate sensorimotor performance using the cylinder rearing test based on extensive use of this test in previous neonatal HI research and ease of comparison to previous work. The test is sensitive to unilateral lesions in all parts of the corticospinal tract (Schallert T, Fleming SM, Leasure JL, Tillerson JL, Bland ST Neuropharmacology. 2000;39:777–87.). Normalization of test performance follows restoration of corticospinal tract function in the neonatal mouse (van Velthoven CTJ, van de Looij Y, Kavelaars A, Zijlstra J, van Bel F, Huppi PS, et al Ann Neurol. 2012;71:785–96.). A disadvantage of this test is that it depends on lateralization of sensorimotor function, but since the Vannucci model is (mostly) unilateral, the test is well suited to this model in our opinion. The addition of a less specific test such as the pole test could perhaps increase the chance of discovering non-lateralized sensorimotor dysfunction. We will keep this in mind when designing experiments in the future. - Concerning no sex-difference in this study allows to concider MEL as a broad spectrum treatment. Thank you for this comment. We agree that this study does not provide evidence against recommending melatonin to either males or females. However, as discussed under “Sex differences in melatoninergic neuroprotection”, we do not feel that our study can answer the question of sex-dependent effects with a high degree of confidence, due to the skewed grouping of males and females in the treatment groups. A sentence addressing this has been added to the discussion. Attachments Attachment Submitted filename: Response to reviewers.docx https://doi.org/10.1371/journal.pone.0225788.r002
13 Nov 2019 Decision Letter - Olivier Baud, Editor Transient effect of melatonin treatment after neonatal hypoxic-ischemic brain injury in rats PONE-D-19-16889R1 Dear Dr. Widerøe, We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements. Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication. Shortly after the formal acceptance letter is sent, an invoice for payment will follow. To ensure an efficient production and billing process, please log into Editorial Manager at https://www.editorialmanager.com/pone/, click the "Update My Information" link at the top of the page, and update your user information. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, you must inform our press team as soon as possible and no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. With kind regards, Olivier Baud, MD, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0225788.r003
Formally Accepted
3 Dec 2019 Acceptance Letter - Olivier Baud, Editor PONE-D-19-16889R1 Transient effect of melatonin treatment after neonatal hypoxic-ischemic brain injury in rats Dear Dr. Widerøe: I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. For any other questions or concerns, please email plosone@plos.org. Thank you for submitting your work to PLOS ONE. With kind regards, PLOS ONE Editorial Office Staff on behalf of Pr. Olivier Baud Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0225788.r004

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