Effects of Moderate- and High-Intensity Chronic Exercise on the Adiponectin Levels in Slow-Twitch and Fast-Twitch Muscles in Rats

Round 1

Reviewer 1 Report

"Dear Authors,

thank you for your interesting manuscript.

Although the adipose tissue is believed the main source of adiponectine, other tissues are able to secrete it, as you stated in your paper. Not very much can be found in literature about this topic. Therefore, your paper about the adiponectin expression in skeletal muscle is interesting and could be published, in my opinion.

The methods about exercise protocols are described in details and are related to previous results in literature.

You should improve English language. At least, try to change the “slow” and “fast” terminology for muscles. It is difficult to understand: “smooth” muscle in the abstract session? Slow-twitch or fast-twitch? Obviously, the difference between plantaris and soleus is based on contraction and metabolic functions, but try to better elucidate this concept for the readers.

Your results are in contrast with some results in humans.

In a recent meta-analysis, (Effects of Physical Exercise on Adiponectin, Leptin, and Inflammatory Markers in Childhood Obesity: Systematic Review and Meta-Analysis. Sirico F, Bianco A, D'Alicandro G, Castaldo C, Montagnani S, Spera R, Di Meglio F, Nurzynska D. Child Obes. 2018 May/Jun;14(4):207-217. doi: 10.1089/chi.2017.0269.) the adiponectin serum levels significantly increase in obese children included in a physical exercise protocol. Moreover, this meta-analysis cited several papers demonstrating lower level of adiponectin in obese children compared to normal weight. Again, several doubts remain about sex differences and pubertal stage about adiponectin, leptin and other pro-inflammatory citochynes.

The adiponectin levels in human are also negatively related to the BMI (and also this point is in contrast with your results).

Probably, you could elucidate better this points in the discussion (as you have done in part in your conclusion session).

These contrasts are normal in my opinion, due to the recent knowledge about this topic. The Table 2 of this recent review (J Exerc Rehabil. 2014 Apr 30;10(2):60-8. doi: 10.12965/jer.140104. eCollection 2014 Apr. Effects of interventions on adiponectin and adiponectin receptors. Lee S, Kwak HB) summarizes several results in human and animal studies, underling these discrepancies.   More consistent results are available about leptin.

In any case, these differences justify your final conclusion about the need to avoid generalizability of these molecules as markers of disease.

Thank you"

Author Response

Reviewer 1

We are really very grateful to your comments that made us to improve the

 MS.

The title was changed and know reads: Effects of moderate- and high-intensity chronic exercise on the adiponectin levels in slow-twitch and fast -twitch muscles in rats.

 

You should improve English language. At least try to change the slow and fast terminology for muscles.

R: Yes you are right, and as you will see we have improved the language in all the text, specially Results, Discussion, and Conclusion sections.   We also changed the ”slow” and  ”fast”  muscles for slow-twitch and fast twitch  all over the text. Professor Arturo Alvarez-Buylla   at San Francisco University helped us with the English language.

 

R.: Yes, you are right, we have tried to respond this matter in Discussion section.

 

R: As you mark “The adiponectin levels in human are also negatively related to the BMI (and also this point is in contrast with your results)”.  We also argued some of the studies and discussed the bibliography you recomended in Discussion section.

R:  I agree with your opinion, this topic is yet new, we need to continue with more experiments.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Journal : Medicina

Title: Effects of moderate-and high-intensity chronic exercise on the adiponectin levels in slow and fast muscles in rats.

 

Reviewer' Comments:

In this manuscript, the authors explored the effect of training intensity on adiponectin expression in slow and fast muscles in male Wistar rats. 
The results showed Groups MIT and HIT reduced the adiponectin protein levels in plasma and plantaris  muscle, an effect that was muscle phenotype-dependent, but did not modify the adiponectin and AdipoR1 receptor gene expression in both muscles. 


The manuscript is well written, easy to read and provides some new findings on this area. Hence some issues must be taken into account.

Main concern: In the current study the effects of the two training modes HIT vs. MIT are not measured and discussed to better appreciate the results. This must be discussed and added to the limitation part in the discussion.

In the abstract, Line 16 replace ca by can.

In the introduction some paragraphs must address what and why we need to know this and what the question you are addressing is and is it really that important. Clearly, the introduction must demonstrate what the current study may add to our knowledge in this area? What is the rationality to choose HIT vs. MIT for example ?

Please discuss the link between exercise and adiponectin in the introduction.

Why the authors choose to study study the effect of training intensity on adiponectin.

Specify in the introduction that the study is conducted in animals. 


Methods:

The authors have provided a detailed, yet concise, account of their study methods and experimental design. However some precisions must be addressed:

-       What was the final number of rats in each group ?

-       How many days the rats trained per week ?

-       Please provide the ICC and CV for all the measurements.

Statistical analysis:

Why authors choose one-way ANOVA? Statistics must be more detailed. The statistical analysis must be more consistent and need to mirror the design and hypothesis to be tested (see: Hopkins, W. G. (2000). A new view of statistics. Internet Society for Sport Science: http://www.sportsci.org/resource/stats/).

In the result paragraph please provide the exact values of P and not only >0.05 or >0.001…

The discussion reflect what the authors found, how it relates to the literature. However there is a lack of what it means physiologically and there are several speculations.

Start the discussion with the main results and not presenting again the objectives of the study.

The body weight changes are not well discussed… the authors must explain why these changes and the differences between gains in MIT and HIT.

The authors stated « …we assume that in our trained rats there was also a decrease in the adipose tissue, that could partially 
explain the lower adiponectin levels, as occur in a previous study… ». This part must be clearly discussed and explained.  


Please provide the limitations of the study.

 

Author Response

Reviewer 2

We are really very grateful with your comments that made us to improve the

 MS.

The title was changed and know reads: Effects of moderate- and high-intensity chronic exercise on the adiponectin levels in slow-twitch and fast -twitch muscles in rats.

 

Main concern: In the current study the effects of the two training modes HIT and MIT are not measured and discussed to better appreciate the results This must be discussed and added to the limitation part in the discussion.

R. Completely agree:  First of all we have changed our English all over the text, after sending the MS to Dr. Arturo Alvarez-Buylla from San Francisco University. As you will see, we also have changed the text in:  Introduction, Discussion and Conclusion sections. I think that now our results are more clear.

In the abstract, line 6 replace ca by can.

R: it is done.

In the introduction some paragraphs must address what and why we need to know this and what the question you are addressing is and is it really that important. Clearly, the introduction must demonstrate what the current study may add to our knowledge in this area? What is the rationality to choose HIT vs MIT for example?

R: We choose whether different exercise intensities could modify adiponectin secretion.

Please discuss the link between exercise and adiponectin in the introduction

R: We already discussed.

 

Why the authors choose to study the effect of training intensity on adiponectin?

R: Because the literature shows that adiponectin increase after exercise is more intense.

Specify in the Introduction that the study is conducted in animals.

R: It is done in the title and all over the text

Methods:

Some precisions must be addressed

What was the final number of rats in each group:

R: It is done in method section

How many days rats trained per week?

R: It is done in method section

Please provide the ICC and CV for all measurements

R: We think CV is the important value for this study, and we have added it in all the measures, see Result section

 

Statistical analysis

Why authors choose on-way ANOVA? Statistics most be more

 Because ANOVA is used to determine whether there are any statistically significant differences between the means of two or more independent (unrelated) groups, and it is used when the work has at least 3 groups.

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authirs respond to all my comments. Congratulations.

Author Response

Dear Dr. Marko Kozlina       

We are sending our revised manuscript number 495284 entitled "Effects of moderate-and high-intensity chronic exercise on the adiponectin levels in slow-twitch and fast-twitch muscles in rats" by Alberto Jiménez-Maldonado, PhD,  Adolfo Virgen-Ortiz, PhD, Mónica Lemus, PhD,  Elena Castro-Rodríguez, PhD, Joel Cerna-Cortés, PhD,  JesúsMuñiz, PhD, Sergio Montero, PhD, and Elena Roces, Biol. for publication in Medicina. Please, note that the title has been changed.

 

As you will see, we have included all your suggestions:

1.- -Introduction, 1st paragraph: Correct "Adipoq is an adipocyte-derived factor1" to "Adipoq is an adipocyte-derived factor [1]" Now it is “[1]”.

2.- The next reference is cited in Discussion:
Martinez-Huenchullan SF, Maharjan BR1, Williams PF, Tam CS, Mclennan SV, Twigg SM. Skeletal muscle adiponectin induction depends on diet, muscle type/activity, and exercise modality in C57BL/6 mice. Physiol Rep. 2018 Oct; 6(20):e13848. doi: 10.14814/phy2.13848. It corresponds to the number 31.

3.- -The following sentence in Conclusion is now replaced as the first paragraph in Discussion:
" It is widely generalized in the literature that a reduction in adiponectin levels is associated with pathologic conditions, such as obesity [19, 20], or diabetes [21, 22]. Furthermore, some authors have suggested that exercise could have a beneficial effect by increasing adiponectin levels [23, 24]. We think that rats doing intense or moderate exercise for 8 weeks have reduced adiponectin protein levels in serum and plantaris muscle. In slow-twitch muscle (Soleus), adiponectin concentration was not altered by moderate or high intensity training”.

4.- The total number of references is now 33, due to the reference 31 in discussion section, and we renumbered references from 19 to 33.

We want to thank you for your help.

Yours sincerely,

 

Elena Roces and Sergio Montero

Corresponding authors

Author Response File: Author Response.docx