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Effect of dietary iron loading on recognition memory in growing rats.

Han M, Kim J - PLoS ONE (2015)

Bottom Line: While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored.These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance.Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron loading in improved memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, United States of America.

ABSTRACT
While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored. To characterize the role of dietary iron loading in memory function in the young, weanling rats were fed iron-loading diet (10,000 mg iron/kg diet) or iron-adequate control diet (50 mg/kg) for one month, during which a battery of behavioral tests were conducted. Iron-loaded rats displayed elevated non-heme iron levels in serum and liver, indicating a condition of systemic iron overload. In the brain, non-heme iron was elevated in the prefrontal cortex of iron-loaded rats compared with controls, whereas there was no difference in iron content in other brain regions between the two diet groups. While iron loading did not alter motor coordination or anxiety-like behavior, iron-loaded rats exhibited a better recognition memory, as represented by an increased novel object recognition index (22% increase from the reference value) than control rats (12% increase; P=0.047). Western blot analysis showed an up-regulation of dopamine receptor 1 in the prefrontal cortex from iron-loaded rats (142% increase; P=0.002). Furthermore, levels of glutamate receptors (both NMDA and AMPA) and nicotinic acetylcholine receptor (nAChR) were significantly elevated in the prefrontal cortex of iron-loaded rats (62% increase in NR1; 70% increase in Glu1A; 115% increase in nAChR). Dietary iron loading also increased the expression of NMDA receptors and nAChR in the hippocampus. These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance. Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron loading in improved memory.

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Effect of dietary iron loading on motor coordination and anxiety-like behavior in growing rats.Rats fed control or iron-loading diet for one month were tested on the rotarod device to record the time to falling-off and speed of the rod (A) and on the elevated plus maze in order to determine anxiety- and impulsivity-related behavior, including time in open arms and overall velocity in the maze (B). Empty and closed bars represent control and iron-loaded rats, respectively. Data were presented as means ± SEM (n = 11 per group) and were analyzed using two-sample t-test. * P < 0.05.
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pone.0120609.g002: Effect of dietary iron loading on motor coordination and anxiety-like behavior in growing rats.Rats fed control or iron-loading diet for one month were tested on the rotarod device to record the time to falling-off and speed of the rod (A) and on the elevated plus maze in order to determine anxiety- and impulsivity-related behavior, including time in open arms and overall velocity in the maze (B). Empty and closed bars represent control and iron-loaded rats, respectively. Data were presented as means ± SEM (n = 11 per group) and were analyzed using two-sample t-test. * P < 0.05.

Mentions: Since altered brain iron is associated with deficits in motor function [31–33], we determined the effect of dietary iron loading on motor coordination by an accelerating rotarod device. Iron-loaded rats fell off the rotarod about 3 min since the start, which was similar to the performance by control rats (Fig. 2A). The peak speed attained on the rotarod by iron-loaded rats was comparable to that by control rats. Since there is a growing body of evidence that impaired iron metabolism is linked to emotional changes [39,40,52], we investigated if dietary iron overload can alter anxiety and/or impulsivity by the elevated plus maze paradigm. Time spent in open arms or overall velocity in the maze was not different between the two groups (Fig. 2B). Iron-loaded rats spent similar time entering an open arm with the number of entries to open and closed arms unchanged (data not shown). Combined, these results suggest that dietary iron loading does not alter motor coordination or emotional behavior in growing rats.


Effect of dietary iron loading on recognition memory in growing rats.

Han M, Kim J - PLoS ONE (2015)

Effect of dietary iron loading on motor coordination and anxiety-like behavior in growing rats.Rats fed control or iron-loading diet for one month were tested on the rotarod device to record the time to falling-off and speed of the rod (A) and on the elevated plus maze in order to determine anxiety- and impulsivity-related behavior, including time in open arms and overall velocity in the maze (B). Empty and closed bars represent control and iron-loaded rats, respectively. Data were presented as means ± SEM (n = 11 per group) and were analyzed using two-sample t-test. * P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352024&req=5

pone.0120609.g002: Effect of dietary iron loading on motor coordination and anxiety-like behavior in growing rats.Rats fed control or iron-loading diet for one month were tested on the rotarod device to record the time to falling-off and speed of the rod (A) and on the elevated plus maze in order to determine anxiety- and impulsivity-related behavior, including time in open arms and overall velocity in the maze (B). Empty and closed bars represent control and iron-loaded rats, respectively. Data were presented as means ± SEM (n = 11 per group) and were analyzed using two-sample t-test. * P < 0.05.
Mentions: Since altered brain iron is associated with deficits in motor function [31–33], we determined the effect of dietary iron loading on motor coordination by an accelerating rotarod device. Iron-loaded rats fell off the rotarod about 3 min since the start, which was similar to the performance by control rats (Fig. 2A). The peak speed attained on the rotarod by iron-loaded rats was comparable to that by control rats. Since there is a growing body of evidence that impaired iron metabolism is linked to emotional changes [39,40,52], we investigated if dietary iron overload can alter anxiety and/or impulsivity by the elevated plus maze paradigm. Time spent in open arms or overall velocity in the maze was not different between the two groups (Fig. 2B). Iron-loaded rats spent similar time entering an open arm with the number of entries to open and closed arms unchanged (data not shown). Combined, these results suggest that dietary iron loading does not alter motor coordination or emotional behavior in growing rats.

Bottom Line: While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored.These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance.Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron loading in improved memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, United States of America.

ABSTRACT
While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored. To characterize the role of dietary iron loading in memory function in the young, weanling rats were fed iron-loading diet (10,000 mg iron/kg diet) or iron-adequate control diet (50 mg/kg) for one month, during which a battery of behavioral tests were conducted. Iron-loaded rats displayed elevated non-heme iron levels in serum and liver, indicating a condition of systemic iron overload. In the brain, non-heme iron was elevated in the prefrontal cortex of iron-loaded rats compared with controls, whereas there was no difference in iron content in other brain regions between the two diet groups. While iron loading did not alter motor coordination or anxiety-like behavior, iron-loaded rats exhibited a better recognition memory, as represented by an increased novel object recognition index (22% increase from the reference value) than control rats (12% increase; P=0.047). Western blot analysis showed an up-regulation of dopamine receptor 1 in the prefrontal cortex from iron-loaded rats (142% increase; P=0.002). Furthermore, levels of glutamate receptors (both NMDA and AMPA) and nicotinic acetylcholine receptor (nAChR) were significantly elevated in the prefrontal cortex of iron-loaded rats (62% increase in NR1; 70% increase in Glu1A; 115% increase in nAChR). Dietary iron loading also increased the expression of NMDA receptors and nAChR in the hippocampus. These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance. Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron loading in improved memory.

Show MeSH
Related in: MedlinePlus