Neuroprotective Effect of Low-Intensity Pulsed Ultrasound Against MPP + -Induced Neurotoxicity in PC12 Cells: Involvement of K2P Channels and Stretch-Activated Ion Channels
Lu Zhao, Yi Feng, Aiwei Shi, Lei Zhang, Shifang Guo, Mingxi Wan
Ultrasound in Medicine & Biology 2017 · 10.1016/j.ultrasmedbio.2017.04.020
Abstract
Parkinson's disease is the second most common neurodegenerative disease. It is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. 1-Methyl-4-phenylpyridinium (MPP+) is a dopaminergic neuronal toxin that is widely used in constructing Parkinson's disease models in vitro. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapeutic approach that has neuromodulation and neuroprotective effects in the central neural system; however, whether LIPUS can provide protection for dopaminergic neurons against MPP+-induced neurocytotoxicity remains unknown. In this study, we found that pre-treatment with LIPUS (1 MHz, 50 mW/cm2, 20% duty cycle and 100-Hz pulse repetition frequency, 10 min) inhibited MPP+-induced neurotoxicity and mitochondrial dysfunction in PC12 cells. LIPUS decreased MPP+-induced oxidative stress by modulating antioxidant proteins, including thioredoxin-1 and heme oxygenase-1, and prevented neurocytotoxicity via the phosphoinositide 3-kinase (PI3K)-Akt and ERK1/2 pathways. Furthermore, these beneficial effects were attributed to the activation of K2P channels and stretch-activated ion channels by LIPUS. These data indicate that LIPUS protects neuronal cells from MPP+-induced cell death through the K2P channel- and stretch-activated ion channel-mediated downstream pathways. The data also suggest that LIPUS could be a promising therapeutic method in halting or retarding the degeneration of dopaminergic neurons in Parkinson's disease in a non-invasive manner.
Abstract via pubmed.
Exposures
Exposure 1: LIPUS pre-treatment of PC12 cells before MPP+ exposure
Target: other — “PC12 cells (differentiated rat pheochromocytoma cell line, dopaminergic-neuron-like in vitro model)”
Device: custom-built · Wuxi Lanhui Electronic, Jiangsu, China · TAPMM25W (1-MHz unfocused flat piezoceramic transducer) ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 2 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 20 | ✓✓✓ |
| Sonication duration (s) | 600 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 0.05 | ✓?⚑ |
| In-situ estimate | not applicable | |
| In-situ pressure (kPa) | not applicable | |
| In-situ Isppa (W/cm²) | not applicable | |
| In-situ Ispta (W/cm²) | not applicable |
Cells were pre-treated with LIPUS (50 mW/cm2) 2 h before treatment with MPP+ (0.5 mM), which was then added to the medium for an additional 12 or 24 h. Ultrasound was delivered as a pulsed sinusoidal signal from an unfocused flat transducer through a degassed 37C water tank to an Opticell cell-culture chamber positioned 106 mm from the transducer. Control cells were cultured without LIPUS, NGF, MPP+ or inhibitors.
Flags from extraction
exposures[0].free_field.ispta_w_cm2— Value is a spatial-average temporal-average (SATA) intensity measured via water-tank propagation to the cell chamber (no biological tissue path); classified as free_field and mapped to ispta_w_cm2 as the closest standard quantity to a temporal-average intensity.exposures[0].timing.pulse_duration_ms— Paper gives duty cycle (20%) and PRF (100 Hz) but never states pulse duration directly; left not_reported rather than compute it.target.terms— PC12 is an immortalized pheochromocytoma cell line used as a dopaminergic-neuron model; no vocabulary id matches exactly, so 'other' was used with a descriptive label.direction_of_effect— Study measures cytoprotection/biochemical signalling rather than excitatory/inhibitory neural activity, so classified as not_assessed.