Low-intensity pulsed ultrasound triggers a beneficial neuromodulation in dementia mice with chronic cerebral hypoperfusion via activation of hippocampal Fndc5/irisin signaling
Degang Song, Xiaomin Chen, Na Zhou, Yi Yuan, Shuo Geng, Cong Zhang, Zhe Zhao, Xingran Wang, Xinran Bao, Xifa Lan, Xiangjian Zhang
Journal of Translational Medicine 2023, 21 · 10.1186/s12967-022-03824-7
Abstract
Background Exercise-related signaling Fndc5/irisin expresses in brain and acts as a crucial regulator of cognitive function, but its detailed roles in vascular dementia (VaD) are still unclear. Low intensity pulsed ultrasound (LIPUS), a novel brain stimulation approach, has been suggested as a promising treatment for dementia. Here, we investigated the activity and efficacy of Fndc5/irisin in experimental VaD, further explored whether the potential effects of LIPUS on VaD is related to Fndc5/irisin. Methods Mouse model of VaD was established with chronic cerebral hypoperfusion (CCH) using bilateral common carotid arteries stenosis (BCAS). Transcranial LIPUS was applied 24 h after BCAS and subsequently daily with a stimulation time of 5 min at an ultrasound pressure of 0.51 MPa for a period of 28 days. The levels of Fndc5/irisin in different brain regions, the hippocampal long-term potentiation and anti-inflammatory cytokines were investigated at day 28 after cognitive evaluation. Global Fndc5 knock-out (F5KO), forced expression or knockdown of Fndc5, and recombinant irisin application were respectively employed for mechanism exploration. The neuron dendritic spine density and astrocyte phenotype were detected in vitro. Results Fndc5/irisin was reduced in hippocampus of BCAS mice, forced expression hippocampal Fndc5 or bilateral intrahippocampal injection of recombinant irisin respectively improved hippocampal synaptic plasticity or inflammatory microenvironment, and then alleviated the cognitive impairments. LIPUS existed a positive efficacy in enhancing hippocampal Fndc5/irisin in BCAS mice, thus triggering a beneficial neuromodulation for VaD protection. Importantly, the neurorestorative effects of LIPUS on CCH-induced damages were totally reversed by knockdown the expression of hippocampal Fndc5 in WT mice, or in F5KO mice. Moreover, Fndc5 mediated the upregulated effects of LIPUS on spine density as well as irisin secretion of hippocampal neurons. The neuron-secreted irisin further drove reactive astrocytes to a neuroprotective phenotype. Conclusion LIPUS induced a neurorestorative stimulation against VaD may be through upregulation of the hippocampal Fndc5/irisin levels. Hippocampal Fndc5/irisin signaling might be a promising strategic target for VaD.
Abstract via europepmc.
Exposures
Exposure 1: Transcranial LIPUS to bilateral hippocampus (in vivo, BCAS mice)
Target: hippocampus — “bilateral hippocampus (irradiation range also covered part of forebrain)”
Device: Olympus / Panametrics · Panametrics · A392S ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | 50 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 1 | ✓✓✓ |
| Duty cycle (%) | 5pulse duration × PRF gives 5% | ✓✓✓ |
| Sonication duration (s) | 300 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Pressure, domain unspecified (kPa) | 510 | ✓✓✓⚑ |
| Ispta, domain unspecified (W/cm²) | 0.528 | ✓✓✓⚑ |
LIPUS used in in vivo experiments was generated by a 1-MHz single-element focused transducer (A392S; Panametrics, Waltham, MA, USA) with 50 ms burst lengths at a 5% duty cycle and a repetition frequency of 1 Hz. a 3D-print coupling cone was used to connect the mouse skull and the transducer. LIPUS was applied 24 h after BCAS and subsequently daily with a stimulation time of 5 min for a period of 28 days.
Exposure 2: LIPUS applied to cultured hippocampal neurons and astrocytes (in vitro)
Target: cultured neurons, cultured glia — “primary hippocampal neuron and astrocyte cultures”
Device: Olympus / Panametrics · Panametrics · A394S-SU ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | 50 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 10 | ✓✓✓ |
| Duty cycle (%) | 50pulse duration × PRF gives 50% | ✓✓✓ |
| Sonication duration (s) | 300 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| 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 | |
| Ispta, domain unspecified (W/cm²) | 0.11 | ✓✓✓⚑ |
A 1-MHz plane piezoelectric transducer (A394S-SU, Panametrics, Waltham, MA, USA) was used to generate LIPUS with 50 ms burst lengths at a 50% duty cycle and a repetition frequency of 10 Hz. The acoustic wave was transmitted from the plane transducer to the bottom of the cell culture plate and daily applied for a stimulation time of 5 min at a period of 2 days.
Flags from extraction
n_subjects— Paper gives only per-group sizes for animals receiving LIPUS across sub-studies (aging BCAS+LIPUS n=24, adult BCAS+LIPUS n=24, F5KO BCAS+LIPUS n=24, BCAS+LIPUS+shLuc/shFndc5 n=90); no single total for all LIPUS-exposed animals is stated, so group sizes are listed rather than summed.subject_unit— Study combines in vivo mouse (animal) and in vitro primary hippocampal neuron/astrocyte culture (culture) work; subject_unit and n_subjects/n_sessions_per_subject given here reflect only the in vivo animal arm.exposures[0].unspecified_domain.pressure_kpa— Abstract states 'ultrasound pressure of 0.51 MPa' while the Methods state 'acoustic power of 0.51 W (corresponding to ISPTA of 528 mW/cm2)' for the same in vivo LIPUS exposure – possible unit/terminology confusion (pressure vs. power) sharing the same numeral 0.51; domain (free-field vs in situ) is not specified for either quantity.exposures[0].unspecified_domain.ispta_w_cm2— Domain (free-field vs in situ) not specified for the stated ISPTA of 528 mW/cm2.exposures[1].unspecified_domain.ispta_w_cm2— Domain not specified for the stated in vitro ISPTA of 110 mW/cm2; a separate, seemingly unrelated value (30 mW/cm2, 'our previous study') is mentioned only as background safety context and was not used.