An Integrated Method for Photothrombotic Stroke Modeling and In Vivo Optrode Recording of Neuronal and Astrocytic Activity in Behaving Mice
May 29th, 2026
This protocol provides an integrated method that includes viral delivery, optrode implantation, photothrombotic induction, simultaneous recording of astrocyte and neuronal activity, and optogenetic stimulation of astrocytes. This integrated method aims to provide concurrent investigation of the astrocyte-neuron relationship across the acute-to-chronic stages of ischemic stroke.
Our research develops an integrated method to simultaneously record astrocytes and neuron activity during ischemic stroke in behaving mice. Previous methods record neurons or astrocytes separately. Our protocol captures astrocytes and neuron signals simultaneously from the very moments of stroke onset.
To begin, transfer a deeply anesthetized C57BL/6J mouse to the stereotaxic frame equipped with an anesthesia mask. Monitor the depth of anesthesia every 10 minutes while maintaining the mouse body temperature between 36 to 37.5 degrees Celsius with a feedback controlled heated pad. Secure the mouse to the stereotaxic frame with ear bars and a mouth bar after applying ophthalmic ointment to the eyes.
Confirm head immobilization by gentle probing once the head is symmetrically fixed. After depilation and a septic skin preparation, use surgical scissors to make a midline incision. Clean the periosteum with saline and cotton swabs to expose bregma and lambda.
Lower the glass micropipette to touch bregma and lambda successively. After noting the Z coordinate on the digital vernier, adjust the mouth bar until the difference is less than 0.04 millimeters. Lower the glass micropipette to touch bregma and reset the digital vernier to zero.
Move the micropipette 2.3 millimeters to the left and right of bregma successively. After noting the Z coordinate, adjust the ear bars until the bilateral differences are less than 0.04 millimeters. After resetting the digital vernier to zero at bregma, mark the motor cortex forelimb area at anterior posterior plus 1.5 millimeters and medial lateral plus 0.74 millimeters.
Use a micro drill and 0.5 millimeter round tip drill bits to drill a small hole, approximately 0.5 millimeters in diameter at the marked location. Before loading, mix the two adeno-associated viral vectors in equal volumes and briefly centrifuge the sample. Lower the glass micropipette connected to the microinfusion pump to the target site at a dorsal-ventral depth of minus 0.94 millimeters from the brain surface.
Infuse 400 nanoliters of the viral mix containing 200 nanoliters of each vector at 50 nanoliters per minute. Slowly withdraw the pipette 10 minutes after the infusion is completed. Suture the scalp with 4-0 20 millimeter, 3/8 circle suture, and place the mouse on a heating pad until full recovery.
Three to four weeks post-viral injection follow the previously demonstrated procedure up to scalp incision. During the scalp incision, remove 1.5 centimeters by 1.5 centimeters of scalp while keeping sufficient skin around the eyes. Clean the skull with hydrogen peroxide and 0.9%saline.
After identifying bregma, reset the digital vernier to zero. Use a 0.8 millimeter round tip drill to lightly roughen the skull surface. Mark the motor cortex forelimb area.
At anterior posterior, 1.5 millimeters and medial lateral 0.74 millimeters. And use the mark as the center point to draw a five millimeter by five millimeter square. Use a micro drill at approximately 10, 000 revolutions per minute to trace the square.
Continuously apply ice cold saline to the drill path and stop immediately if the bone flap loosens. Drill three small 0.5 millimeter diameter holes over the contralateral hemisphere and cerebellum. Implant cranioplasty screws into the holes.
Ensure that each screw reaches the dura mater but does not penetrate further to avoid damage to the brain tissue. Use forceps to remove the loosened bone flap. Use ultrafine forceps with an ultrafine tip smaller than 0.03 millimeters by 0.01 millimeters to remove the dura at the cranial window while avoiding direct contact with brain tissue.
Fix the optrode to the micromanipulator arm of the stereotaxic frame and move it above the cranial window. Securely intertwine the silver ground and reference wires of the optro to the three cranioplasty screws. Clean the cranial window surface with sterile saline.
Slowly lower the optro to the desired dorsal-ventral depth of minus 0.94 millimeters at one millimeter per 10 seconds. Apply a layer of agarose over the cranial window after implantation. Apply three to four layers of dental cement.
Once the dental cement solidifies, provide analgesia for three to five days and allow the mouse to recover for one to two weeks. Use a dual or triple wavelength fiber photometry system to excite GCaMP6s. Set the signal channel to 470 nanometers and the control channel to 410 nanometers.
Adjust the sampling rate to 60 frames per second. Now, ground all recording system components properly. Use a common median reference during recording.
Verify that wide band and local field potential signals are selected in the recording software while monitoring for noise throughout the recording session. After anesthetizing the mouse briefly, connect the optro to the recording line through an adapter. Place the mouse in a homecage-like environment for recording.
Allow 10 minutes of acclimatization after awakening. Record the mouse performing the grip strength test, requiring one pull per minute for five minutes. Timestamp behavioral tests precisely in both multichannel and fiber photometry systems.
Administer 1.5%Rose Bengal dye solution intraperitoneally at 10 to 20 milligrams per kilogram and wait for five minutes. Connect the optrode probe to the laser source once deep anesthesia is achieved and maintained. Deliver a 530 nanometer laser beam at 15 milliwatts through the implanted optrode for five to eight minutes to induce focal ischemia.
To perform optogenetic stimulation, connect the laser stimulator to the optrode. Turn on the 488 nanometer optogenetic laser stimulator and set it to 10 milliwatts for five minutes for Opto-vTrap. Finally, place the mouse into a heated pad for recovery.
Compared with baseline, cerebral blood flow declined after photothrombosis and remained suppressed at one day and seven days post-stroke. Forelimb grip strength showed a highly significant decline at one day and remained suppressed at seven days post-stroke. The astrocytic calcium transients recorded by fiber photometry and neuronal spikes from electrophysiology were aligned based on timestamps.
Following photothrombotic stroke, firing rates were significantly suppressed in both pyramidal neurons and interneurons as compared to the baseline firing during the forelimb grip task. At baseline, the astrocytic calcium transients peaked within four to six seconds of task onset. But the amplitude was significantly reduced after photothrombotic stroke, reflecting weakened calcium activity.
Raster plots and peri-stimulus time histograms showed changes in neuronal activity during optical stimulation. Both the pyramidal neuron and interneuron firing rates showed a significant decrease after optical stimulation compared with the pre-stimulus baseline, confirming that astrocyte modulation has a measurable downstream effect on local circuit excitability. This protocol allows uninterrupt recording of exercise and neuroactivity across the fore stroke timeline from the acute on sign to chronic stage.
Success in this protocol relies on precise or co-ordinate alignment. Monocular optro implantation and sufficient virus expression temps across the surgeries. Future study could use multiple implants to monitor broader brain regions or target different cell types with diverse behavioral assays.
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Overview
This protocol introduces an integrated method for investigating astrocyte-neuron interactions following ischemic stroke in awake, behaving mice. By combining photothrombotic stroke induction with simultaneous multichannel electrophysiology and fiber photometry using a custom optrode, the approach enables real-time, multimodal recordings of neuronal and astrocytic activity during behavioral tasks. The method addresses limitations of previous techniques by allowing concurrent induction, recording, and optogenetic manipulation without multiple surgeries.
Key Study Components
Area of Science
- Neuroscience
- Stroke research
- Electrophysiology
- Optogenetics
Background
- Astrocyte-neuron dynamics are critical for post-stroke recovery.
- Existing methods often lack the ability to monitor real-time interactions during behavior.
- Acute phase stroke pathology is difficult to study with traditional approaches.
- Simultaneous recording and manipulation of both cell types in behaving animals is technically challenging.
Purpose of Study
- To develop a protocol for real-time, multimodal recording of astrocyte and neuron activity after stroke.
- To enable investigation of acute and chronic stroke phases in behaving mice.
- To validate the system's ability to manipulate and monitor astrocyte-neuron interactions.
Methods Used
- Photothrombotic induction of focal ischemia in mouse cortex.
- Simultaneous multichannel electrophysiology to record neuronal spikes.
- Fiber photometry for monitoring astrocytic calcium transients.
- Custom-fabricated optrode for concurrent photothrombosis, recording, and optogenetic manipulation.
Main Results
- Successful simultaneous recording of astrocytic calcium signals and neuronal spiking in awake, behaving mice.
- Optogenetic stimulation of astrocytes led to measurable reductions in firing frequency of both pyramidal neurons (by 1.55 ± 0.45 Hz) and interneurons (by 3.64 ± 1.37 Hz; n = 2).
- The system enables investigation of astrocyte-neuron interactions in real time during behavioral tasks.
- Representative results validate the integrated approach for stroke research.
Conclusions
- The protocol fills a critical methodological gap in stroke research.
- It allows for real-time, multimodal investigation of cellular interactions from acute to chronic stroke stages.
- The approach facilitates studies of astrocyte-neuron dynamics during behavior, advancing understanding of post-stroke recovery mechanisms.
Frequently Asked Questions
Executive Industry Relevance
Real-time, multimodal interrogation of astrocyte-neuron interactions in behaving animals addresses a critical gap in preclinical stroke research. This integrated method enhances predictive confidence in target validation and mechanistic de-risking for neurovascular and neuroinflammatory pathways. The approach supports translational continuity from acute to chronic stroke phases, informing portfolio decisions in CNS drug discovery.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct testing of neuro-glial interaction hypotheses in disease-relevant models.
- Supports mechanistic de-risking by linking astrocytic modulation to neuronal output changes.
- Facilitates functional target validation for astrocyte and neuron signaling pathways.
Screening & Assay Development
- Provides a validated platform for quantitative, simultaneous readouts of neuronal and astrocytic activity.
- Enables reproducible assessment of pharmacological or genetic interventions in real time.
- Supports assay standardization for high-content screening of neuroactive compounds.
Translational & Preclinical Research
- Aligns preclinical models with human disease-relevant mechanisms by capturing acute and chronic stroke dynamics.
- Enables longitudinal studies of intervention effects on cellular interactions during behavior.
- Improves risk-adjusted advancement by providing predictive, multimodal biomarkers.
Pipeline & Workflow Integration
This method bridges early discovery and preclinical validation by enabling real-time, in vivo analysis of neuro-glial dynamics post-stroke in behaving mice.
- Discovery Biology: Supports hypothesis testing on astrocyte-neuron signaling and pathway modulation after ischemic injury.
- Screening: Delivers quantitative, reproducible outputs for compound or genetic screening in a physiologically relevant context.
- Analytics: Provides simultaneous electrophysiological and calcium imaging data for robust statistical comparison of intervention effects.
- Translational Research: Facilitates alignment of preclinical findings with clinical endpoints by modeling acute and chronic stroke phases.
- Enterprise Reuse: Offers a reusable platform for diverse CNS disease models requiring real-time, multimodal interrogation.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in neurovascular target validation.
- Operational Value: Streamlines workflows by integrating induction, recording, and manipulation in a single procedure.
- Strategic Value: Enables better go/no-go decisions through robust, translationally relevant data.
- Portfolio Impact: Supports risk-adjusted prioritization of CNS assets by providing high-content, disease-relevant readouts.
Implementation Considerations
- Requires expertise in in vivo electrophysiology, fiber photometry, and optogenetics.
- Demands specialized instrumentation, including custom optrodes and synchronized recording systems.
- Necessitates cross-team standardization for data acquisition and analysis protocols.
- Adaptation to other CNS disease models may require protocol optimization.
- Potential limitations include technical complexity and the need for behavioral training of animal models.