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The effects of preweaning manganese exposure on spatial learning ability and p-CaMKIIα level in the hippocampus
HuanHuan Fu1, WeiWei Chen1, HongPing Yu2
1MOE-Shanghai Key Lab of Children Environmental Health, XinHua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Background:
The effects and mechanisms of preweaning Manganese (Mn) exposure on cognitive dysfunction remain unclear.
Objective:
This study evaluated the effects of preweaning Mn exposure on spatial learning and memory as well as the protein expression of CaMKIIα and p-CaMKIIα.
Methods:
We treated neonate rats with Mn(2+) doses of 0 (control group), 10, 20 and 30mg of Mn(2+) per kg body weight (Mn-exposed groups) over postnatal day (PND) 1-21 by intraperitoneal injection. The ability of spatial learning and memory was tested on PND 22 using the Morris water maze (MWM), while the protein expressions of CaMKIIα and p-CaMKIIα in the hippocampus were evaluated by Western blotting. The levels of Mn in the blood and hippocampus were measured by inductively coupled plasma-mass spectrometry (ICP-MS).
Results:
The rats in Mn-exposed groups showed a significant delay in spatial learning ability on the third day of the MWM without dose-dependent differences, but there was no effect on the spatial memory ability. p-CaMKIIα, but not CaMKIIα protein expression significantly reduced in the Mn-exposed group.
Conclusion:
These findings suggested that the inhibition of p-CaMKIIα could be one of the mechanisms involved in the occurrence of Mn-induced cognitive impairments.
Insights
Preweaning manganese exposure impairs spatial learning in rats by reducing p-CaMKIIα protein in the hippocampus, suggesting a mechanism for cognitive dysfunction.
Area of Science:
- Neuroscience
- Toxicology
- Developmental Biology
Background:
- Preweaning exposure to manganese (Mn) and its impact on cognitive function are not well understood.
- Investigating the mechanisms behind Mn-induced cognitive deficits is crucial for public health.
Purpose of the Study:
- To assess the effects of early-life manganese exposure on spatial learning and memory in rats.
- To examine the protein expression levels of CaMKIIα and its phosphorylated form (p-CaMKIIα) in the hippocampus.
Main Methods:
- Neonate rats were exposed to varying doses of manganese (Mn(2+)) from postnatal day 1-21.
- Spatial learning and memory were evaluated using the Morris water maze (MWM) test.
- Hippocampal protein expression of CaMKIIα and p-CaMKIIα was analyzed via Western blotting.
Main Results:
- Manganese exposure delayed spatial learning on the third day of MWM testing.
- No significant effect on spatial memory retrieval was observed.
- A significant reduction in p-CaMKIIα protein levels was found in manganese-exposed rats, while CaMKIIα levels remained unchanged.
Conclusions:
- Inhibition of p-CaMKIIα may be a key mechanism underlying manganese-induced cognitive impairments.
- Early-life manganese exposure can disrupt hippocampal signaling pathways critical for learning.
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