Review for 10.1186/1471-230X-11-127 (2011)

Reviewer's report
Title:Change of nitric oxide synthase neurons in ileal myenteric plexus of rat
severe acute pancreatitis
Version: 1Date:20 April 2011
Reviewer: Colin R Anderson
Reviewer's report:
This paper presents data showing that severe acute pancreatitis in rats results in
an increase in the proportion of enteric neurons expressing NOS in the terminal
ileum. This is an interesting observation but the context in which it is discussed
could be improved. In addition, some key data needed to interpret the result are
not included. In addition, while the current version of the paper can be
understood relatively clearly, the grammar and proofing needs to be improved.
With the necessary changes, this paper should be publishable in BMC
Gastroenterology.
Major compulsory revisions
The key result of the paper should be presented as I have done in the first
sentence above. The paper only presents information on the change of NOS
neuron proportions. It does not provide evidence that the NOS neurons are
responsible for the changes in motility although this is an obvious hypothesis to
guide future work. I suggest that the abstract and discussion are rewritten to
change the emphasis in this way. Thus, rewrite the section in the abstract that
reads “The aim of this study was to explore the nervous mechanism of
pancreatitis-induced gastrointestinal dysmotility ……” as the paper provides no
evidence that the mechanism of changed motility is due to the increase in
proportion of NOS neurons in the terminal ileum. After all, the delay in transit time
is almost certainly due to changes in motility in the stomach and upper small
intestine, areas not examined in this study. In addition, it is impossible to predict
what effect an assumed increased release of NO will have on motility.
The information missing from the results is whether the total number of Hu
neurons changes or remains the same. As NOS neurons are only recorded as a
proportion of the total (Hu) neurons, an increase in the proportion of NOS
neurons could come about through an increase in the total number of neurons
expressing NOS or a decrease in the total number of neurons, i.e death of
non-NOS neurons. While the increase in NOS mRNA suggests the former, it
does not prove it. In addition, there is no information on whether the NOS
expression remains confined to the MP after SAP or whether it is also expressed
in the SMP. Finally, the size increase is only given as a mean. This information
should be shown as a size frequency plot before and after SAP, so the reader
can see how the size distribution changes. It should provide evidence on which
neurons, large or small, now express NOS after SAP.
In the discussion, large parts of the first and second paragraphs repeat
information (sometimes exactly) from the introduction and should be discarded.
The first half of the third paragraph and all of the fourth paragraph are very basic
and should be shortened to make only the relevant points. The start of the fifth
paragraph of the discussion talks about CB1 receptors and ascetic fluid, but I
have no idea how these points relate to the present study. Overall, I found the
discussion overlong and generally vague. It should be shorter and limited to the
relevant points.
Minor essential revisions
The title is not helpful. Can I suggest “Increased proportion of nitric oxide
synthase neurons in rat ileal myenteric plexus after severe acute pancreatitis”?
If errors are to be included in the abstract, state that they are SEMs. The abstract
is designed to be read alone.
The inclusion of the value for nNOS mRNA after SAP in the abstract is
meaningless unless the control value is also given.
The second last sentence of the first paragraph of the Introduction reads as a
prediction. If it is a statement of fact, it needs a reference.
In the M & M, the pancreatitits grading is listed as “modified” but no idea of how it
was modified is given. I suspect that it was carried out exactly as described in the
references, which themselves were describing a modified procedure. If this is the
case, do not refer here to the procedure as modified.
Table one lists the Hu and NOS antibodies as mouse and rabbit antibodies
respectively but list goat antibodies to visualise them.
Overall the paper needs a modest amount of attention from an English language
editor. They layout includes many additional spaces and there are issues with
font size in the references.
Discretionary revisions
An important experiment that has not been attempted but which would shed
some light on the mechanism of dysmotility would be to identify which classes of
neurons now express NOS after SAP. Both morphology (Dogiel type I vs type II
neurons) and neurochemistry (e.g. ChAT to mark excitatory motor neurons)
might identify which neurons are now expressing NOS after SAP.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests