The neurotoxic effects of exposure of primary cultured hippocampal neurons to a 50 Hz magnetic field and the protective effects of lotus seedpod procyanidins should be investigated.
Lotus seedpod procyanidins (LSPCs) possess a broad spectrum of biological, pharmacological and chemoprotective properties against free radicals and oxidative stress. In a previous study by the authors (Duan et al. 2013), it was found that LSPCs had a protective effect against oxidative damage after ELF-EMF exposure in in vivo experiments.
Cells were divided into 5 groups: 1) exposure to the magnetic field, 2) exposure to the magnetic field and treatment with 2.5 mg/ml LSPCs, 3) exposure to the magnetic field and treatment with 5 mg/ml LSPCs, 4) exposure to the magnetic field and treatment with 10 mg/ml LSPCs, 5) control group.
Exposure duration: continuous for 90 minutes
|Exposure duration||continuous for 90 minutes|
|Chamber||cell culture plates|
|Setup||a pair of Helmholtz coils (1.0 mm wire diameter, 9 cm internal diameter, 13 cm external diameter) in 400 turns, parallel to the ground, generated a homogeneous field|
|magnetic flux density||8 mT||-||measured||-||-|
Cell viability, SOD enzyme activity and mitochondrial membrane potential were significantly decreased in exposed cells (group 1) compared to the control group, while lipid peroxidation, calcium concentration and the content of reactive oxygen species were significantly increased. However, in exposed groups with LSPCs (group 2-4), all these parameters were significantly restored in a LSPC concentration-dependent manner compared with group 1.
In morphological investigations, cells of group 1 showed a rounder shape and fewer neurites as well as condensed and fragmented nuclei compared to the control group. In a combination with 10 mg/ml LSPCs (group 4), morphology was significantly improved.
DNA damage, apoptosis and necrosis were significantly increased in group 1 compared to the control group. In groups 3 (with 5 mg/ml LSPCs) and 4, these parameters were significantly reduced in a LSPC concentration-dependent manner compared to group 1.
Cell cycle analysis revealed a significantly decreased number of cells in G0 phase/G1 phase and a significant S phase arrest in group 1 when compared with the control group. The LSPCs groups 3-4 showed a concentration-dependent restoration of both parameters compared to group 1.
The protein expressions of Bcl-2 and Bcl-xl were significantly decreased and the levels of Bad and Bax significantly increased in group 1 compared with the control group. LSPCs treatment increased the levels of anti-apoptotic proteins Bcl-2 and Bcl-xl and decreased the levels of pro-apoptotic proteins Bad and Bax.
The authors conclude that exposure to a 50 Hz magnetic field might induce neurotoxicity in hippocampal neurons via oxidative stress and activation of mitochondrial apoptotic pathway and that lotus seedpod procyanidins might protect against these effects.