Reviewer's report
Title:Psychological stress decreased iron absorption in rats
Version: 1Date:10 June 2009
Reviewer: Phillip S Oates
Reviewer's report:
This is an interesting paper regarding the effect of psychological stresshas on
intestinal iron absorption. It involves providing rats 4-5 weeks of age(assumed
given the weight) with bursts of electrical shock at 30 sec intervals. I assume
ethical approval has been given for this protocol as I cannot see a statement to
this effect.
The results suggest that although dietary intake and therefore iron absorption
was the same, feacal iron absorption decreased with the length of PS and that
this was ferroportin/hepcidin dependent. Although this is the conclusion no data
is included here regarding hepcidin although a previous study indicates this
relationship.
Major issues with this study that need to be resolved:
Hepatic hepcidin expression needs to be included on these rats to confirm the
temporal pattern of iron absorption.
Spleen iron and ferroportin expression should be presented to demonstrate the
hypoferremia is not due to retention of iron by macrophages. It is likely
macrophages contribute significantly to the hypoferremia measured and be the
more potent factor than intestinal iron absorption.
Importantly, the nature of the intestinal iron measurements are indirect rather
than direct such as using isotopic measurements, the preferred method.
Moreover the experimental design also may be problematic, that is PS is likely to
increase intestinal transit. The fact that defacation was a response to PS
indicates loss of control of bowel movements. Since non haem iron absorption is
confined to the duodenum any rapid/uncontrolled gastric emptying will make iron
absorption inefficient and this may account for the decreased iron absorption
measured. This can be estimated by the period of the red coloration appearing in
the feaces (not included) but still this is not as good as measuring isotopic iron
absorption in duodenal situ gut sacs which is direct.
The way in which the protein was harvested from the duodenum appears
suboptimal. The lack of protease inhibitors in the buffers used to recover protein
from the duodenum is fraught with problems as the duodenum contains high
levels of pancreatic derived proteases which can rapidly degrade the protein.
In summary although interesting the data is not convincing in its demonstration of
PS affects on iron absorption via hepcidin/ferroportin.
Reviewer's report
Title:Psychological stress decreased iron absorption in rats
Version: 1Date:10 June 2009
Reviewer: Phillip S Oates
Reviewer's report:
This is an interesting paper regarding the effect of psychological stresshas on
intestinal iron absorption. It involves providing rats 4-5 weeks of age(assumed
given the weight) with bursts of electrical shock at 30 sec intervals. I assume
ethical approval has been given for this protocol as I cannot see a statement to
this effect.
The results suggest that although dietary intake and therefore iron absorption
was the same, feacal iron absorption decreased with the length of PS and that
this was ferroportin/hepcidin dependent. Although this is the conclusion no data
is included here regarding hepcidin although a previous study indicates this
relationship.
Major issues with this study that need to be resolved:
Hepatic hepcidin expression needs to be included on these rats to confirm the
temporal pattern of iron absorption.
Spleen iron and ferroportin expression should be presented to demonstrate the
hypoferremia is not due to retention of iron by macrophages. It is likely
macrophages contribute significantly to the hypoferremia measured and be the
more potent factor than intestinal iron absorption.
Importantly, the nature of the intestinal iron measurements are indirect rather
than direct such as using isotopic measurements, the preferred method.
Moreover the experimental design also may be problematic, that is PS is likely to
increase intestinal transit. The fact that defacation was a response to PS
indicates loss of control of bowel movements. Since non haem iron absorption is
confined to the duodenum any rapid/uncontrolled gastric emptying will make iron
absorption inefficient and this may account for the decreased iron absorption
measured. This can be estimated by the period of the red coloration appearing in
the feaces (not included) but still this is not as good as measuring isotopic iron
absorption in duodenal situ gut sacs which is direct.
The way in which the protein was harvested from the duodenum appears
suboptimal. The lack of protease inhibitors in the buffers used to recover protein
from the duodenum is fraught with problems as the duodenum contains high
levels of pancreatic derived proteases which can rapidly degrade the protein.
In summary although interesting the data is not convincing in its demonstration of
PS affects on iron absorption via hepcidin/ferroportin.
Please review this paper.
user
Reviewer's report
Title:Psychological stress decreased iron absorption in rats
Version: 1Date:10 June 2009
Reviewer: Phillip S Oates
Reviewer's report:
This is an interesting paper regarding the effect of psychological stresshas on
intestinal iron absorption. It involves providing rats 4-5 weeks of age(assumed
given the weight) with bursts of electrical shock at 30 sec intervals. I assume
ethical approval has been given for this protocol as I cannot see a statement to
this effect.
The results suggest that although dietary intake and therefore iron absorption
was the same, feacal iron absorption decreased with the length of PS and that
this was ferroportin/hepcidin dependent. Although this is the conclusion no data
is included here regarding hepcidin although a previous study indicates this
relationship.
Major issues with this study that need to be resolved:
Hepatic hepcidin expression needs to be included on these rats to confirm the
temporal pattern of iron absorption.
Spleen iron and ferroportin expression should be presented to demonstrate the
hypoferremia is not due to retention of iron by macrophages. It is likely
macrophages contribute significantly to the hypoferremia measured and be the
more potent factor than intestinal iron absorption.
Importantly, the nature of the intestinal iron measurements are indirect rather
than direct such as using isotopic measurements, the preferred method.
Moreover the experimental design also may be problematic, that is PS is likely to
increase intestinal transit. The fact that defacation was a response to PS
indicates loss of control of bowel movements. Since non haem iron absorption is
confined to the duodenum any rapid/uncontrolled gastric emptying will make iron
absorption inefficient and this may account for the decreased iron absorption
measured. This can be estimated by the period of the red coloration appearing in
the feaces (not included) but still this is not as good as measuring isotopic iron
absorption in duodenal situ gut sacs which is direct.
The way in which the protein was harvested from the duodenum appears
suboptimal. The lack of protease inhibitors in the buffers used to recover protein
from the duodenum is fraught with problems as the duodenum contains high
levels of pancreatic derived proteases which can rapidly degrade the protein.
In summary although interesting the data is not convincing in its demonstration of
PS affects on iron absorption via hepcidin/ferroportin.
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