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Updated: Jun 3, 2026
Measurement of Total Calcium in Neurons by Electron Probe X-ray Microanalysis
Published on: November 20, 2013
The effect of exogenous melamine on rat hippocampal neurons
Yan Wang1, Fei Liu, Yuejiao Wei
1Key Laboratory of Animal Resistance, College of Life Science, Shandong Normal University, Jinan, China.
Abstract:
Rat hippocampal neurons in culture medium were exposed to different concentrations of melamine. By examining the morphology of cells detected with acridine orange staining, different changes of fluorescences of Ca²⁺ observed with Fluo3, and caspase-3 activity assayed with optical density by enzyme linked immunosorbent assay kit, we found the effect of melamine on hippocampal neurons. Pathologic changes happened in hippocampal neurons, and there seemed to be insoluble metabolites in most of the cells with 312 µg/mL melamine stimulated for 12 hours. Then, we tested the Ca²⁺ fluorescences of the cells above. The free intracellular Ca²⁺ concentrations were measured using the fluorescent dye Fluo3. The average fluorescence of Ca²⁺ in hippocampal neurons stimulated by 312 µg/mL melamine (55.43 ± 3.54) was higher than the normal ones (6.94 ± 0.14). Besides, caspase-3 activity of hippocampal neurons after being challenged with melamine was higher than that of normal ones in the mass. From the above conclusions, melamine did induce damnification to hippocampal neurons, probably in the way of inducing cells to undergo apoptotic processes and disrupting the homeostasis of Ca²⁺. Our experimental results disproved some viewpoints that not melamine alone, but melamine and cyanuric acid in combination could cause damage in toxicological studies and provided compelling evidence that low levels of melamine exposure may also represent a health risk to nerves, in opposition to the idea that damage of melamine and cyanuric acid in combination were limited to the kidneys.
Insights
Melamine exposure causes nerve damage in rat hippocampal neurons by disrupting calcium homeostasis and inducing apoptosis. This study provides evidence that even low levels of melamine pose a health risk to the nervous system.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Melamine's toxicological effects are debated, with some studies suggesting it primarily damages kidneys when combined with cyanuric acid.
- Previous research has not conclusively determined if melamine alone poses a risk to neural tissues.
Purpose of the Study:
- To investigate the direct impact of melamine on rat hippocampal neurons.
- To elucidate the mechanisms underlying melamine-induced neuronal damage, focusing on calcium homeostasis and apoptosis.
Main Methods:
- Rat hippocampal neurons were exposed to varying melamine concentrations.
- Cell morphology was assessed using acridine orange staining.
- Intracellular calcium (Ca²⁺) levels were measured with Fluo3 fluorescence.
- Caspase-3 activity was quantified using an enzyme-linked immunosorbent assay (ELISA).
Main Results:
- Melamine exposure induced pathological changes and insoluble metabolite formation in hippocampal neurons.
- A significant increase in intracellular Ca²⁺ fluorescence was observed in melamine-treated neurons (55.43 ± 3.54) compared to controls (6.94 ± 0.14).
- Caspase-3 activity, an indicator of apoptosis, was elevated in neurons exposed to melamine.
Conclusions:
- Melamine directly damages hippocampal neurons, likely by disrupting Ca²⁺ homeostasis and triggering apoptotic pathways.
- These findings challenge the notion that melamine's toxicity is limited to kidney damage and only occurs in combination with cyanuric acid.
- Low-level melamine exposure represents a potential health risk to the nervous system.
