L-Type Calcium Channel Modulates Low-Intensity Pulsed Ultrasound-Induced Excitation in Cultured Hippocampal Neurons
Wen-Yong Fan, Yi-Ming Chen, Yi-Fan Wang, Yu-Qi Wang, Jia-Qi Hu, Wen-Xu Tang, Yi Feng, Qian Cheng, Lei Xue
Neuroscience Bulletin 2024 · 10.1007/s12264-024-01186-2
Abstract
As a noninvasive technique, ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo. The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and further impact the electrophysiological properties of targeted neurons. However, the underlying mechanism of low-intensity pulsed ultrasound (LIPUS)-induced neuro-modulation effects is still unclear. Here, we characterize the excitatory effects of LIPUS on spontaneous activity and the intracellular Ca 2+ homeostasis in cultured hippocampal neurons. By whole-cell patch clamp recording, we found that 15 min of 1-MHz LIPUS boosts the frequency of both spontaneous action potentials and spontaneous excitatory synaptic currents (sEPSCs) and also increases the amplitude of sEPSCs in hippocampal neurons. This phenomenon lasts for > 10 min after LIPUS exposure. Together with Ca 2+ imaging, we clarified that LIPUS increases the [Ca 2+ ] cyto level by facilitating L-type Ca 2+ channels (LTCCs). In addition, due to the [Ca 2+ ] cyto elevation by LIPUS exposure, the Ca 2+ -dependent CaMKII-CREB pathway can be activated within 30 min to further regulate the gene transcription and protein expression. Our work suggests that LIPUS regulates neuronal activity in a Ca 2+ -dependent manner via LTCCs. This may also explain the multi-activation effects of LIPUS beyond neurons. LIPUS stimulation potentiates spontaneous neuronal activity by increasing Ca 2+ influx.
Abstract via europepmc.
Exposures
Exposure 1: LIPUS 1 MHz, 15 min, cultured hippocampal neurons
Target: cultured neurons — “cultured hippocampal neurons”
Device: not reported
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | 300 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 0.3 | ✓✓✓⚑ |
| Duty cycle (%) | 10pulse duration × PRF gives 9%, which disagrees with the stated value | ✓✓✓ |
| Sonication duration (s) | 900 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 0.05, 0.1, 0.2swept | ✓✓✓ |
| 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 |
1 MHz tone bursts of 300 ms at PRF 0.3 Hz (10% duty cycle) for 15 min; 100 mW/cm2 ISPTA used for the electrophysiology and imaging work. For expression and morphology experiments, 15 min every 12 h for 1 or 2 days.
Flags from extraction
exposures[0].timing.pulse_repetition_frequency_hz— Text states PRF 0.3 Hz; the Figure 1 legend states 0.33 Hz.exposures[0].unspecified_domain.ispta_w_cm2— ISPTA 50, 100, 200 mW/cm2 converted to W/cm2; the figure says intensities were measured with a hydrophone, but the text does not tie the stated ISPTA values to a water or in-situ domain.exposures[0].timing.sonication_duration_s— 15 min of stimulation recorded as 900 s.exposures[0].device.family— Transducers described as 1 MHz plane piezoelectric transducers driven by a home-designed generator; no transducer maker named.n_subjects— Cultures from 1 to 2 day old rats; number of animals or cultures not stated.