Development of a photochemical thrombosis investigation system to obtain a rabbit ischemic stroke model

Protocol to measure monosynaptic connections between different cortical regions in mice using cell-pair cross correlogram of spike events

Neuromodulation can facilitate interactions between neurons to rescue impaired brain function after stroke. Here, we present a protocol for measuring putative monosynaptic connections between different cortical regions. We detail procedures for tetrode fabrication, implantation surgery, stroke induction in mice, multi-site in vivo electrophysiological recording, units clustering, principal neuron/interneuron classification, and functional connection analysis. This protocol allows us to understand the mechanisms of stroke recovery. For complete details on the use and execution of this protocol, please refer to Wang et al.1.

Positive Neuroprotective Effect of Argon Inhalation after Photochemically Induced Ischemic Stroke Model in Rats

We studied the effect of 2-h inhalation of argon-oxygen mixture (Ar 70%/O2 30%) after photochemically induced stroke and on days 2 and 3 after stroke modeling on the severity of neurological deficit and brain damage (by MRI data) in Wistar rats. Neurological deficit was assessed within 14 days using the limb placement test. MRI and histological study of the brain with an assessment of the size of damage were performed on day 14 after ischemia. Significant differences were obtained in limb placement scores on days 3, 7, and 14, as well as in the volume of ischemic focus by MRI in comparison with the control (ischemia+N2 70%/O2 30%). Inhalation of argon-oxygen mixture for 2 h a day over 3 days after photoinduced stroke decreased the volume of brain damage by 2 times and reduced the severity of neurological deficit.

Application of rectal balloon ice water stimulation for the rehabilitation of stroke patients with neurogenic bowel dysfunction

BACKGROUND

Neurogenic bowel dysfunction (NBD) is a common complication in stroke patients.

OBJECTIVE

To investigate the effect of rectal balloon ice water stimulation on the rehabilitation of patients with NBD after a cerebral stroke.

METHODS

Forty stroke patients with NBD were selected between March and August 2022 and randomly divided into a study group (n = 20) and a control group (n = 20). Based on routine rehabilitation training, rectal balloon ice water stimulation or finger rectal stimulation were performed on the study or control group, respectively. After two weeks, the changes in the NBD, self-rating depression scale (SDS) and self-rating anxiety scale (SAS) scores were compared between the two groups.

RESULTS

Before the intervention, there were no significant differences in age, sex ratio, and NBD, SDS and SAS scores between the two groups (p > 0.05). The NBD, SDS and SAS scores of both groups were significantly decreased following intervention (p < 0.05). After 2 weeks of intervention, the NBD score of the study group was significantly lower than that of the control group (5.50±1.28 vs 6.45±1.05; p = 0.014). The SDS score of the study group was lower than that of the control group, and the difference was statistically significant (32.30±2.81 vs 44.05±2.19; p = 0.014). The study group also had significantly lower SAS scores than the control group (p = 0.024). In addition, the incidence of dizziness, headaches, nausea, vomiting and abdominal pain and distension in the study group was significantly lower than in the control group (p < 0.05).

CONCLUSION

Rectal balloon ice water stimulation can significantly improve stroke patients with NBD's intestinal function and psychological status.

Novel Animal Model of Spontaneous Cerebral Petechial Hemorrhage Using Focused Ultrasound in Rats

Background and Objectives: Petechial cerebral hemorrhages can be caused by various factors, such as traumas, cerebral infarctions, and aging, and is related to the disruption of the blood–brain barrier or the cellular damage of blood vessels. However, there is no animal model that recapitulates cerebral petechial hemorrhages. Materials and Methods: Here, we implemented a petechial hemorrhage using a novel technology, i.e., microbubble-assisted focused ultrasound (MB + FUS). Results: This method increases the permeability of the blood–brain barrier by directly applying mechanical force to the vascular endothelial cells through cavitation of the microbubbles. Microbubble-enhanced cavitation has the advantage of controlling the degree and location of petechial hemorrhages. Conclusions: We thus generated a preclinical rat model using noninvasive focal MB + FUS. This method is histologically similar to actual petechial hemorrhages of the brain and allows the achievement of a physiologically resembling petechial hemorrhage. In the future, this method shall be considered as a useful animal model for studying the pathophysiology and treatment of petechial cerebral hemorrhages.

In vivo tissue optical clearing assisted through-skull targeted photothrombotic ischemic stroke model in mice

SIGNIFICANCE

Photothrombotic stroke is an important and widely used model for ischemic stroke research. However, the significant scattering of the skull during the procedure limits the light's ability to penetrate and focus on its target. Targeted photothrombosis uses surgery-based skull windows to obtain optical access to the brain, but it renders the brain's environment unnatural even before a stroke is established.

AIM

To establish a targeted, controllable ischemic stroke model in mice through an intact skull.

APPROACH

The in vivo skull optical clearing technique provides a craniotomy-free "optical window" that allows light to penetrate. Alongside the local photodynamic effect, we have established targeted photothrombosis without skull removal, effectively controlling the degree of thrombotic occlusion by changing the light dose.

RESULTS

Ex vivo and in vivo results demonstrated that skull optical clearing treatment significantly enhanced light's ability to penetrate the skull and focus on its target, contributing to thrombotic occlusion. The skull optical clearing window was also used for continuous blood flow mapping, and the relationship between light dose and injury degree was evaluated over 14 days of monitoring. Per our findings, increasing the light dose was accompanied by more severe infarction, indicating that the model was easily controllable.

CONCLUSIONS

Herein, a targeted, controllable ischemic stroke model was established by combinedly running an in vivo skull optical clearing technique and a photothrombotic procedure, avoiding unnecessary damage or environmental changes to the brain caused by surgery on the skull. Our established model should offer significant value to research on ischemic stroke.

Preliminary Study on Safety Assessment of 10 Hz Transcranial Alternating Current Stimulation in Rat Brain

Assessment of the safety of transcranial electrical stimulation devices that contact the scalp and apply electrical stimulations to brain tissues is essential for the prevention of unexpected brain damage caused by electromagnetic fields. In particular, safety studies on transcranial alternating current stimulation (tACS) are needed for active applications to treat brain diseases and for the development of medical devices, because there is a lack of research on the safety of tACS, in contrast to transcranial direct current stimulation. In this study, the safety of tACS with selected parameters, i.e., a stimulation intensity of 1.0 to 2.0 mA, a frequency of 10 Hz, and a treatment time of 20 min, was examined at a preclinical stage using small animals (rats). The results of magnetic resonance imaging and histopathological imaging indicated that the conditions applied in this study provided safe tACS without damaging brain tissues or neuronal components in the acute phase. In addition, the temperature did not increase above 41 °C, which is a temperature limitation for contact-type medical devices, even after 20 min of tACS application.

Optical Modalities for Research, Diagnosis, and Treatment of Stroke and the Consequent Brain Injuries

Stroke is the second most common cause of death and third most common cause of disability worldwide. Therefore, it is an important disease from a medical standpoint. For this reason, various studies have developed diagnostic and therapeutic techniques for stroke. Among them, developments and applications of optical modalities are being extensively studied. In this article, we explored three important optical modalities for research, diagnostic, and therapeutics for stroke and the brain injuries related to it: (1) photochemical thrombosis to investigate stroke animal models; (2) optical imaging techniques for in vivo preclinical studies on stroke; and (3) optical neurostimulation based therapy for stroke. We believe that an exploration and an analysis of previous studies will help us proceed from research to clinical applications of optical modalities for research, diagnosis, and treatment of stroke.