Impact of manganese on primary hippocampal neurons from rodents

Abstract

Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful tool for in vivo tract tracing or functional imaging of the central nervous system. However Mn(2+) may be toxic at high levels. In this study, we addressed the impact of Mn(2+) on mouse hippocampal neurons (HN) and neuron-like N2a cells in culture, using several approaches. Both HN and N2a cells not exposed to exogenous MnCl2 were shown by synchrotron X-ray fluorescence to contain 5 mg/g Mn. Concentrations of Mn(2+) leading to 50% lethality (LC50) after 24 h of incubation were much higher for N2a cells (863 mM) than for HN (90 mM). The distribution of Mn(2+) in both cell types exposed to Mn(2+) concentrations below LC50 was perinuclear whereas that in cells exposed to concentrations above LC50 was more diffuse, suggesting an overloading of cell storage/detoxification capacity. In addition, Mn(2+) had a cell-type and dose-dependent impact on the total amount of intracellular P, Ca, Fe and Zn measured by synchrotron X-ray fluorescence. For HN neurons, immunofluorescence studies revealed that concentrations of Mn(2+) below LC50 shortened neuritic length and decreased mitochondria velocity after 24 h of incubation. Similar concentrations of Mn(2+) also facilitated the opening of the mitochondrial permeability transition pore in isolated mitochondria from rat brains. The sensitivity of primary HN to Mn(2+) demonstrated here supports their use as a relevant model to study Mn(2+) -induced neurotoxicity.

Manganese Exposure Aggravates β-Amyloid Pathology by Microglial Activation

“…Cell viability was calculated using the method described in the CCK-8 kit. Following the method of Daoust et al ( 2014 ), a linear fit to the cell viability data points estimated the 50% lethal concentration (LC 50 ) to be 687.0 μM MnCl 2 for N2a cells under our experimental condition, roughly similar to the reported LC 50 of 863 μM MnCl 2 for N2a cells (Daoust et al, 2014 ); at 100 μM, Mn did not induce any detectable cytotoxicity. Thus, we used 100 μM MnCl 2 in most of our experiments on cultured cells.…”

Age-related cognitive decline coincides with accelerated volume loss of the dorsal but not ventral hippocampus in mice

“…Nevertheless, we cannot rule out that age‐related structural and behavioral changes might partially result from long‐term accumulation of Mn 2+ which has been repeatedly injected as contrast agent to enable semiautomatic MRI‐based morphometry. However, the likelihood of carry‐over effects appears to be minimal given (i) the minimal toxicity of systemic as compared to intracerebral MnCl 2 treatment (Daoust et al, ) in particular in the end of a week of daily injections (Grünecker et al, ), (ii) the rather short half‐life time of Mn 2+ in the brain (5–7 days depending on the brain structure; Grünecker et al, ), and the fact that MEMRI was always performed after WCM training with a time gap of more than 5 months to the next training session.…”

Visualizing Metal Content and Intracellular Distribution in Primary Hippocampal Neurons with Synchrotron X-Ray Fluorescence

“…In hippocampal and dopaminergic neurons exposed to manganese in culture, manganese appears to accumulate in a peri-nuclear location likely to include the Golgi apparatus [ 52 , 71 , 72 ]. Because of low levels of manganese detected in the present study, a convincing peri-nuclear spatial distribution in resting primary neurons was not obtained.…”