Neuropathological Mechanisms of Cerebral Infarction

Cerebral infarction is focal ischemic injury of brain tissue caused by interruption or marked reduction of cerebral blood flow. Its core pathological process is not a single vascular occlusion event, but an ischemic cascade initiated after insufficient blood perfusion. Energy metabolism failure, disruption of ion homeostasis, excitotoxicity, calcium overload, oxidative stress, inflammatory responses, blood-brain barrier disruption, and multiple forms of cell death amplify one another, ultimately leading to injury of neurons, glial cells, and cerebral microvascular structures.

Keywords: cerebral infarction; ischemic stroke; neuropathological mechanism; ischemic penumbra; excitotoxicity; oxidative stress; neuroinflammation; blood-brain barrier

1 Pathological Basis of Cerebral Infarction

1.1 Basic Process of Cerebral Infarction

(1) Blood flow interruption

Cerebral infarction is usually caused by cerebral arterial thrombosis, embolism, or severe stenosis. After vascular occlusion, oxygen and glucose supply to the affected brain region rapidly decreases. Neurons, which are highly dependent on aerobic metabolism, are the earliest cells to be injured. If ischemia persists, local brain tissue progresses from functional impairment to irreversible necrosis.

(2) Ischemic core

The ischemic core is located in the area with the most severe reduction in blood flow. ATP is rapidly depleted, ion pumps fail, the cell membrane depolarizes, and neurons and glial cells undergo necrosis, apoptosis, or mixed forms of death. Tissue damage in this region is usually difficult to reverse and constitutes the major part of the final infarct lesion.

(3) Ischemic penumbra

The ischemic penumbra surrounds the ischemic core, where blood flow is reduced but not completely lost. Cells in this region are functionally impaired, but within a certain time window, they may still survive through reperfusion, metabolic support, and neuroprotective intervention. The penumbra is a key region for mechanistic research and therapeutic intervention in cerebral infarction.

1.2 Injury of the Neurovascular Unit

(1) Neurons

Neurons are the most sensitive cells to oxygen and glucose deprivation. After ischemia, neurons first show abnormal electrical activity, disturbed synaptic transmission, loss of membrane potential, and excessive glutamate release, followed by excitotoxicity, calcium overload, and cell death.

(2) Glial cells

Astrocytes maintain ion homeostasis, take up glutamate, and support blood-brain barrier function. Microglia are the resident immune cells of the brain. Oligodendrocytes maintain myelin structure. After cerebral infarction, glial cells participate in injury amplification but also contribute to clearance of necrotic tissue, restriction of inflammatory spread, and tissue repair.

(3) Cerebral microvessels

Cerebral microvascular endothelial cells, pericytes, basement membrane, and astrocytic endfeet together form the blood-brain barrier. Ischemia and reperfusion can disrupt endothelial tight junctions, increase blood-brain barrier permeability, and induce cerebral edema, inflammatory cell infiltration, and risk of hemorrhagic transformation.

Table 1 Main Structural Units in the Neuropathological Process of Cerebral Infarction

Structural Unit	Main Function	Pathological Changes After Cerebral Infarction
Neurons	Information transmission, synaptic activity, functional output	Energy depletion, depolarization, excitotoxicity, death
Astrocytes	Glutamate uptake, ion homeostasis, blood-brain barrier support	Reduced glutamate clearance, glial scar formation, inflammatory regulation
Microglia	Immune surveillance, phagocytosis, inflammatory regulation	Rapid activation and release of cytokines and ROS
Oligodendrocytes	Myelin formation and axonal support	Myelin injury and impaired neural conduction
Endothelial cells	Blood-brain barrier and regulation of vascular tone	Tight junction disruption and increased permeability
Pericytes	Microvascular stabilization and blood flow regulation	Capillary constriction and microcirculatory disturbance
Basement membrane	Structural support of blood vessels	MMP-mediated degradation, barrier disruption, and aggravated edema

2 Vascular Occlusion and Local Ischemia

2.1 Thrombosis and Embolism

(1) Thrombosis

Thrombosis often occurs on the basis of atherosclerosis, endothelial injury, and a hypercoagulable state. After endothelial injury, collagen and tissue factor are exposed, platelets adhere, activate, and aggregate, and the coagulation cascade is initiated. A fibrin network forms and stabilizes the thrombus. As the thrombus gradually enlarges, it can cause cerebral arterial stenosis or complete occlusion.

(2) Embolism

Embolism refers to emboli originating from the heart, aortic arch, or proximal large vessels entering the cerebral circulation with blood flow and blocking distal vessels. Atrial fibrillation, valvular heart disease, mural thrombus, and rupture of atherosclerotic plaques can all generate emboli. Embolic cerebral infarction often has acute onset, marked local perfusion reduction, and rapid dynamic changes in the ischemic penumbra.

(3) Microcirculatory obstruction

Even after recanalization of large vessels, the microcirculation may still show a “no-reflow” phenomenon. Endothelial swelling, leukocyte adhesion, platelet microthrombi, pericyte contraction, and capillary collapse can all restrict local tissue reperfusion, allowing ischemic injury to continue progressing.

2.2 Hemodynamic Changes After Ischemia

(1) Decreased cerebral blood flow perfusion

Brain tissue is highly dependent on blood flow supply. After vascular occlusion, local cerebral blood flow perfusion decreases significantly, oxygen and glucose input become insufficient, and clearance of metabolic waste is restricted. If cerebral perfusion pressure falls beyond the autoregulatory capacity, neuronal electrical activity and ion homeostasis rapidly lose control.

(2) Collateral circulation compensation

Collateral circulation can provide partial blood flow to ischemic regions through the circle of Willis, leptomeningeal arterial anastomoses, and local microvascular networks. Better collateral circulation prolongs maintenance of the ischemic penumbra and expands the salvageable tissue range. When collateral circulation is insufficient, the ischemic core expands faster, resulting in a larger final infarct volume.

(3) Dual effects of reperfusion

Reperfusion can restore oxygen and nutrient supply and is an important condition for rescuing the penumbra. However, sudden restoration of blood flow may also induce oxidative stress, endothelial injury, inflammatory cell infiltration, and blood-brain barrier disruption, forming ischemia-reperfusion injury.

3 Energy Metabolism Failure and Disruption of Ion Homeostasis

3.1 ATP Depletion

(1) Interruption of aerobic metabolism

Brain tissue mainly relies on aerobic oxidation of glucose to produce ATP. After ischemia, oxygen supply is interrupted, mitochondrial oxidative phosphorylation is blocked, and ATP production decreases sharply. ATP insufficiency directly affects Na⁺/K⁺-ATPase, Ca²⁺ pumps, and synaptic vesicle cycling, preventing neurons from maintaining basic membrane potential and signal transmission.

(2) Ion pump failure

After ATP depletion, Na⁺/K⁺-ATPase function declines, Na⁺ and water enter cells, causing cytotoxic edema; K⁺ efflux leads to membrane depolarization; Ca²⁺ influx and calcium release from the endoplasmic reticulum and mitochondria together cause intracellular calcium overload. Disruption of ion homeostasis is an early key event in the ischemic cascade.

(3) Collapse of synaptic function

Energy insufficiency disrupts neurotransmitter release, reuptake, and vesicle cycling. The excitatory neurotransmitter glutamate accumulates in the synaptic cleft, inhibitory neuromodulation becomes insufficient, and the neural network shifts from reversible functional impairment to structural injury.

3.2 Anaerobic Glycolysis and Acidosis

(1) Anaerobic metabolic compensation

Under hypoxic conditions, cells generate a small amount of ATP through anaerobic glycolysis to temporarily maintain basic metabolism. This compensation has some protective significance in the early stage of ischemia, but its energy efficiency is far lower than that of aerobic metabolism and cannot sustain neuronal activity for long.

(2) Lactate accumulation

When pyruvate cannot enter the tricarboxylic acid cycle, it is converted into lactate, leading to intracellular acidosis. Acidosis can inhibit enzyme activity, disrupt membrane protein function, aggravate ion channel abnormalities, and promote lysosomal injury and cell death.

(3) Metabolic network imbalance

A reduced NAD⁺/NADH ratio affects multiple redox reactions and energy metabolism enzyme activities. Accumulation of metabolic intermediates, mitochondrial dysfunction, and redox imbalance jointly drive expansion of neuronal injury.

Table 2 Main Consequences of Energy Metabolism Failure After Cerebral Infarction

Pathological Link	Direct Change	Downstream Injury
Decreased oxygen supply	Oxidative phosphorylation blockade	Reduced ATP and decreased mitochondrial function
ATP depletion	Ion pump failure	Membrane depolarization and cellular edema
Na⁺ influx	Increased osmotic pressure	Cytotoxic edema
Ca²⁺ overload	Activation of calcium-dependent enzymes	Degradation of proteins, lipids, and cytoskeleton
Enhanced anaerobic glycolysis	Lactate accumulation	Acidosis and reduced enzyme activity
NAD⁺/NADH imbalance	Blocked redox reactions	Metabolic disturbance and cell death

4 Excitotoxicity and Calcium Overload

4.1 Excessive Glutamate Release

(1) Neuronal depolarization

Ischemia disrupts neuronal membrane potential and causes abnormal glutamate release from presynaptic neurons. At the same time, energy insufficiency in astrocytes impairs glutamate transporter function and weakens glutamate clearance from the synaptic cleft, resulting in sustained elevation of extracellular glutamate concentration.

(2) Excessive activation of glutamate receptors

Excess glutamate activates NMDA receptors, AMPA receptors, and metabotropic glutamate receptors. After excessive opening of NMDA receptors, large amounts of Ca²⁺ enter neurons. Changes in permeability of some AMPA receptors can further aggravate Ca²⁺ influx. Sustained receptor activation converts excitatory signaling into cytotoxic injury.

(3) Failure of astrocyte protection

Under normal conditions, astrocytes clear glutamate through EAAT transporters and maintain local ion homeostasis through potassium buffering. Under ischemic conditions, astrocyte energy insufficiency, swelling, and dysfunction lead to reduced glutamate clearance, further amplifying excitotoxicity.

4.2 Injury Effects of Calcium Overload

(1) Activation of calcium-dependent enzymes

Excessive intracellular Ca²⁺ activates calpains, phospholipases, endonucleases, and nitric oxide synthase. These enzymes degrade the cytoskeleton, membrane phospholipids, and nucleic acids, leading to membrane structural damage, DNA injury, and cell death.

(2) Mitochondrial injury

After large amounts of Ca²⁺ enter mitochondria, mitochondrial membrane potential decline, permeability transition pore opening, and respiratory chain dysfunction can occur. Mitochondria can no longer effectively produce ATP and generate more ROS, forming a positive feedback loop between calcium overload and oxidative stress.

(3) Formation of NO and peroxynitrite

Calcium overload can activate neuronal nitric oxide synthase and increase NO generation. NO reacts with superoxide to form peroxynitrite, which can nitrate proteins, damage lipids, and disrupt DNA. It is one of the important molecules mediating ischemic neurotoxicity.

5 Oxidative Stress and Ischemia-Reperfusion Injury

5.1 Sources of ROS and RNS

(1) Mitochondrial electron leakage

During ischemia, the mitochondrial respiratory chain is impaired. After reperfusion, oxygen re-enters ischemic tissue, and the damaged respiratory chain undergoes electron leakage and generates superoxide. Mitochondrial ROS are an important source of oxidative injury in the early stage of reperfusion.

(2) Xanthine oxidase system

During ischemia, ATP breakdown increases and hypoxanthine accumulates. Xanthine dehydrogenase can be converted into xanthine oxidase. During reperfusion, oxygen supply is restored, and xanthine oxidase catalyzes hypoxanthine metabolism, producing large amounts of ROS.

(3) Respiratory burst of inflammatory cells

Neutrophils, monocytes, and activated microglia can produce ROS through NADPH oxidase. While clearing necrotic tissue, inflammatory cells may also release free radicals, proteases, and cytokines, damaging surrounding viable tissue.

5.2 Effects of Oxidative Injury

(1) Lipid peroxidation

ROS attack polyunsaturated fatty acids in cell membranes and organelle membranes, triggering lipid peroxidation reactions. Lipid peroxidation products such as MDA and 4-HNE can disrupt membrane fluidity and permeability and further modify proteins, aggravating membrane damage and cell death.

(2) Protein oxidation

Free radicals can cause protein carbonylation, thiol oxidation, abnormal disulfide bond formation, and decreased enzyme activity. After ion channels, metabolic enzymes, cytoskeletal proteins, and synaptic proteins are damaged, neuronal function deteriorates further.

(3) DNA damage

ROS and RNS can cause base oxidation, single-strand breaks, and double-strand breaks. DNA damage activates repair responses. If damage exceeds repair capacity, apoptosis, necrosis, or other forms of cell death are induced.

5.3 Mechanistic Features of Reperfusion Injury

(1) Coexistence of oxygen supply restoration and ROS burst

Reperfusion can rescue the ischemic penumbra, but it can also cause rapid ROS generation, endothelial dysfunction, and microcirculatory injury. Tissue outcome after reperfusion therapy depends on the speed of blood flow restoration, ischemia duration, microcirculatory status, and antioxidant defense capacity.

(2) Blood-brain barrier disruption

Oxidative stress can activate matrix metalloproteinases, degrade tight junction proteins and basement membrane components, and increase blood-brain barrier permeability. After plasma protein leakage and water entry into the brain parenchyma, vasogenic edema may form, increasing the risk of hemorrhagic transformation.

6 Neuroinflammation and Blood-Brain Barrier Disruption

6.1 Microglial Activation

(1) Early immune surveillance

Microglia rapidly sense DAMPs, ATP leakage, ionic changes, and cellular debris after ischemia. Early microglia can phagocytose necrotic tissue and release repair-related factors. However, excessive activation can release TNF-α, IL-1β, IL-6, ROS, and NO, aggravating neuronal injury.

(2) Phenotypic transition

Microglia are not simply divided into pro-inflammatory or anti-inflammatory states, but instead show continuous spectrum-like changes. Microglia in different time points and brain regions may simultaneously express genes related to inflammation, phagocytosis, antigen presentation, and tissue repair. Studies of inflammatory mechanisms in cerebral infarction should focus on time windows and spatial heterogeneity.

6.2 Infiltration of Peripheral Immune Cells

(1) Neutrophils

After blood-brain barrier disruption and upregulation of adhesion molecules, neutrophils enter ischemic regions. Neutrophils release proteases, ROS, and neutrophil extracellular traps, aggravating endothelial injury, microthrombus formation, and tissue inflammation.

(2) Monocytes and macrophages

After peripheral monocytes enter brain tissue, they can differentiate into macrophages and clear necrotic cells and myelin debris together with microglia. Moderate phagocytosis contributes to repair, whereas excessive inflammation expands tissue injury.

(3) Lymphocytes

T cells and other lymphocytes can participate in post-infarction inflammatory amplification and immune regulation. Different T-cell subsets have different effects on brain injury and repair; they may promote inflammation, but may also participate in immunosuppression and tissue repair.

6.3 Inflammatory Factors and Blood-Brain Barrier Injury

(1) Pro-inflammatory factors

TNF-α, IL-1β, and IL-6 can upregulate adhesion molecules such as ICAM-1 and VCAM-1, promoting leukocyte adhesion and migration. Pro-inflammatory factors can also enhance excitotoxicity, induce apoptosis, and aggravate endothelial barrier disruption.

(2) Anti-inflammatory factors

Anti-inflammatory factors such as IL-10 and TGF-β can limit the release of pro-inflammatory factors, reduce inflammatory injury, and promote tissue repair. If the anti-inflammatory response is insufficient or delayed, inflammation may continue expanding and further damage the penumbra.

(3) MMP-mediated barrier degradation

Matrix metalloproteinases such as MMP-2 and MMP-9 can degrade basement membrane and tight junction proteins, disrupting blood-brain barrier structure. Increased MMP activity is closely associated with cerebral edema, inflammatory cell infiltration, and hemorrhagic transformation.

Table 3 Main Participating Factors in Post-Infarction Inflammatory Responses

Participating Factor	Main Role	Pathological Significance
Microglia	Release inflammatory factors and phagocytose debris	Participate in both injury and repair
Neutrophils	Release ROS, proteases, and NETs	Aggravate microvascular injury and inflammation
Monocytes/macrophages	Phagocytose necrotic tissue and secrete cytokines	Regulate inflammatory clearance and repair
TNF-α	Upregulates adhesion molecules and promotes apoptosis	Aggravates neuronal injury and leukocyte infiltration
IL-1β	Activates glial cells and inflammatory pathways	Amplifies inflammatory responses
IL-10	Inhibits release of pro-inflammatory factors	Limits inflammatory injury
MMP-9	Degrades basement membrane and tight junctions	Promotes blood-brain barrier disruption and edema

7 Cell Death Modes and Tissue Remodeling

7.1 Necrosis and Apoptosis

(1) Necrosis

In the ischemic core, severe energy depletion causes rapid rupture of cell membranes and release of intracellular contents, triggering strong inflammatory responses. Necrosis mainly occurs in regions with the most severe ischemia and fastest ATP depletion.

(2) Mitochondrial pathway apoptosis

Ischemia, oxidative stress, and calcium overload can lead to decreased mitochondrial membrane potential, cytochrome C release, and formation of the apoptotic signaling complex by Apaf-1 and Caspase-9, followed by Caspase-3 activation and programmed cell death.

(3) Death receptor pathway apoptosis

Ligands such as TNF-α and FasL can activate death receptor pathways, recruit FADD, and activate Caspase-8. Caspase-8 can directly activate Caspase-3 and can also connect to the mitochondrial apoptotic pathway through Bid.

7.2 Emerging Forms of Regulated Cell Death

(1) Pyroptosis

Inflammasome activation after ischemia can induce activation of Caspase-1 or related inflammatory caspases, promote maturation and release of IL-1β and IL-18, and form membrane pores through gasdermin family proteins, causing inflammatory cell death. Pyroptosis links inflammatory responses with cell death and is an important mechanism of inflammation amplification after cerebral infarction.

(2) Ferroptosis

Ferroptosis is driven by iron-dependent lipid peroxidation. Brain tissue is rich in polyunsaturated fatty acids and is sensitive to lipid peroxidation. Ischemia-reperfusion, iron homeostasis disturbance, GSH depletion, and decreased GPx4 function can all promote ferroptosis. Ferroptosis is associated with injury to neurons, oligodendrocytes, and blood vessels.

(3) Necroptosis

Necroptosis is mediated by signaling molecules such as RIPK1, RIPK3, and MLKL and has features of programmed necrosis. This process can occur under inflammatory factor stimulation and limited caspase activity, releasing DAMPs and aggravating local inflammation.

(4) Abnormal autophagy

Moderate autophagy helps clear damaged mitochondria and protein aggregates and reduces cellular stress. Excessive or blocked autophagy may lead to cell death or repair failure. In cerebral infarction research, enhanced autophagy initiation should be distinguished from a true increase in autophagic flux.

7.3 Glial Responses and Tissue Repair

(1) Astrocyte response

After cerebral infarction, astrocytes proliferate and form glial scars. Glial scars can restrict inflammatory spread and tissue destruction, but they may also block axonal regeneration and neural network reconstruction.

(2) Oligodendrocytes and myelin injury

Oligodendrocytes are sensitive to ischemia and oxidative stress. Their death leads to myelin injury, impaired axonal conduction, and white matter damage, which are important bases for motor and cognitive dysfunction after cerebral infarction.

(3) Angiogenesis and neural remodeling

After ischemia, HIF-1α, VEGF, and inflammatory mediators can promote angiogenesis. Angiogenesis, axonal sprouting, synaptic remodeling, and glial regulation jointly participate in functional reconstruction during the recovery phase, but their effects are influenced by infarct size, inflammatory environment, and rehabilitation intervention.

Table 4 Cell Death Modes and Key Markers After Cerebral Infarction

Cell Death Mode	Main Mechanism	Common Markers
Necrosis	ATP depletion and membrane rupture	LDH release, cell swelling, loss of membrane integrity
Apoptosis	Caspase cascade	Cleaved Caspase-3, Bax/Bcl-2, TUNEL
Pyroptosis	Inflammasome activation and membrane pore formation	NLRP3, Caspase-1, GSDMD, IL-1β
Ferroptosis	Iron-dependent lipid peroxidation	Decreased GPx4, increased ACSL4, MDA, 4-HNE, Fe²⁺
Necroptosis	RIPK1/RIPK3/MLKL pathway	p-RIPK3, p-MLKL
Abnormal autophagy	Autophagy initiation or flux blockade	LC3-II, p62, Beclin-1

8 Experimental Evaluation in Mechanistic Studies of Cerebral Infarction

8.1 Animal Models

(1) MCAO model

The middle cerebral artery occlusion model is commonly used in mechanistic studies of cerebral infarction and can simulate focal cerebral ischemia and reperfusion injury. The intraluminal filament MCAO model is suitable for studying the ischemic core, penumbra, reperfusion injury, inflammation, and neurological deficits.

(2) Photothrombotic model

The photothrombotic model induces local vascular occlusion using a photosensitizer and specific illumination. The infarct region is relatively stable, making it suitable for studies of focal cortical ischemia and tissue repair. However, collateral circulation and reperfusion processes differ from those in clinical large-vessel occlusion.

(3) Embolic model

The embolic model more closely resembles vascular occlusion by thrombi or emboli and can be used to study thrombolysis, thrombosis, embolic sources, and risk of hemorrhagic transformation. However, model stability and control of infarct size are more difficult.

8.2 Histological and Molecular Detection

(1) Infarct volume evaluation

TTC staining is commonly used to evaluate infarct volume in the acute phase. Nissl staining can reveal neuronal structure, and HE staining can show tissue necrosis and edema. When cerebral edema is obvious, infarct volume should be corrected to avoid overestimating the extent of injury.

(2) Neuronal and glial cell markers

NeuN can be used for neuronal detection, GFAP for astrocyte responses, Iba1 for microglia, MBP for myelin integrity, and CD31 for microvascular structure. Combined use of multiple markers can more completely reflect neurovascular unit injury.

(3) Mechanistic indicator detection

Energy metabolism can be evaluated by ATP, lactate, and mitochondrial membrane potential. Oxidative stress can be evaluated by ROS, MDA, 4-HNE, 8-OHdG, and GSH/GSSG. Inflammation can be evaluated by TNF-α, IL-1β, IL-6, NLRP3, and MMP-9. Cell death can be assessed using Caspase-3, GPx4, GSDMD, p-MLKL, and related markers.

8.3 Neurological Function Evaluation

(1) Motor function

Rotarod, balance beam, neurological function scoring, and foot-fault tests can be used to evaluate motor coordination, balance, and hemiparesis severity. Behavioral indicators should be selected according to model type and time point.

(2) Sensory and cognitive function

Adhesive removal test, tactile stimulation test, Morris water maze, novel object recognition, and Y-maze can be used to evaluate sensory neglect, learning and memory, and cognitive function. Chronic-phase studies should place greater emphasis on cognitive and fine motor recovery.

(3) Result integration

Cerebral infarction research should not rely only on a single infarct volume or a single molecular indicator. A more complete evaluation should integrate tissue injury, cell death, inflammatory response, oxidative stress, blood-brain barrier status, and behavioral function.

Table 5 Common Evaluation Indicators in Mechanistic Studies of Cerebral Infarction

Research Module	Common Indicators	Main Significance
Infarct injury	TTC, Nissl, HE, MRI	Determines infarct range and tissue structural injury
Energy metabolism	ATP, lactate, mitochondrial membrane potential	Evaluates ischemic metabolic failure
Excitotoxicity	Glutamate, NMDA receptors, Ca²⁺	Evaluates neurotransmitter imbalance and calcium overload
Oxidative stress	ROS, MDA, 4-HNE, 8-OHdG, GSH/GSSG	Determines the degree of oxidative injury
Inflammatory response	Iba1, TNF-α, IL-1β, IL-6, NLRP3	Evaluates microglial activation and inflammation amplification
Blood-brain barrier	Evans blue, IgG leakage, ZO-1, occludin, MMP-9	Determines barrier disruption and edema risk
Cell death	TUNEL, Caspase-3, GPx4, GSDMD, p-MLKL	Distinguishes different death mechanisms
Functional recovery	Neurological function score, rotarod, foot-fault test, water maze	Evaluates neurobehavioral outcomes

Table 6 Small Molecules, Staining Probes, and Intervention Reagents Related to Neuropathological Mechanism Studies of Cerebral Infarction

Research Module	Product Name	CAS No.	Application Positioning
Cerebral infarction model evaluation	TTC (2,3,5-Triphenyltetrazolium chloride)	298-96-4	Staining evaluation of infarct area in animal models of cerebral infarction
Cerebral infarction model evaluation	Evans Blue	314-13-6	Detection of blood-brain barrier permeability and vascular leakage
Brain histopathological staining	Toluidine Blue O	92-31-9	Nissl staining and observation of neuronal morphology
Brain histopathological staining	Cresyl Violet	10510-54-0	Nissl body staining and evaluation of neuronal injury
Brain histopathological staining	Hematoxylin	517-28-2	Nuclear staining in HE staining
Brain histopathological staining	Eosin Y	17372-87-1	Cytoplasmic and tissue structure staining in HE staining
Energy metabolism failure	Sodium L-lactate	867-56-1	Research on lactate metabolism and post-ischemic acidosis
Energy metabolism failure	Sodium pyruvate	113-24-6	Energy metabolism supplementation and mitochondrial function research
Energy metabolism failure	2-Deoxy-D-glucose	154-17-6	Glycolysis inhibition and energy metabolism failure models
Excitotoxicity	L-Glutamic acid	56-86-0	Construction of glutamate excitotoxicity models
Excitotoxicity	Monosodium L-glutamate	142-47-2	Glutamate receptor activation and excitotoxicity research
Excitotoxicity	NMDA	6384-92-5	NMDA receptor-mediated calcium overload model
Excitotoxicity	MK-801	77086-21-6	NMDA receptor antagonist for excitotoxicity validation
Calcium overload research	A23187 calcium ionophore	52665-69-7	Construction of intracellular calcium overload models
Calcium overload research	BAPTA-AM	126150-97-8	Intracellular calcium chelation and validation of calcium-dependent injury
Oxidative stress model	tert-Butyl hydroperoxide (t-BHP)	75-91-2	Construction of stable oxidative stress models
Oxidative stress model	Menadione	58-27-5	Induction of intracellular ROS generation
Mitochondrial injury	Rotenone	83-79-4	Inhibits mitochondrial complex I and simulates mitochondrial ROS injury
Mitochondrial membrane potential	JC-1	3520-43-2	Detection of decreased mitochondrial membrane potential
ROS detection	DCFH-DA	4091-99-0	Preliminary screening of total cellular ROS levels
Superoxide detection	Dihydroethidium (DHE)	104821-25-2	Detection of intracellular superoxide
Lipid peroxidation detection	BODIPY 581/591 C11	217075-36-0	Detection of lipid peroxidation and ferroptosis-related lipid ROS
Lipid peroxidation injury	4-Hydroxynonenal (4-HNE)	75899-68-2	Marker of lipid peroxidation injury
DNA oxidative damage	8-Hydroxydeoxyguanosine (8-OHdG)	88847-89-6	DNA oxidative damage standard or detection control
Antioxidant intervention	N-Acetylcysteine (NAC)	616-91-1	ROS scavenging and GSH precursor supplementation
Antioxidant intervention	Trolox	53188-07-1	Water-soluble vitamin E analogue and antioxidant positive control
Antioxidant intervention	Coenzyme Q10	303-98-0	Mitochondrial antioxidant and energy metabolism protection research
Antioxidant intervention	Melatonin	73-31-4	ROS scavenging and mitochondrial protection research
Glutathione system	Reduced glutathione (GSH)	70-18-8	Antioxidant buffering system research
Glutathione system	Oxidized glutathione (GSSG)	27025-41-8	Analysis of GSH/GSSG redox status
Glutathione depletion	L-Buthionine sulfoximine (BSO)	83730-53-4	Inhibits GSH synthesis and increases oxidative stress and ferroptosis sensitivity
Ferroptosis induction	Erastin	571203-78-6	Induces GSH depletion and ferroptosis
Ferroptosis induction	RSL3	1219810-16-8	Inhibits GPx4 and induces lipid peroxidation and ferroptosis
Ferroptosis inhibition	Ferrostatin-1	347174-05-4	Ferroptosis rescue experiments and mechanistic validation
Ferroptosis inhibition	Liproxstatin-1	950455-15-9	Inhibits lipid peroxidation and validates ferroptosis
Iron chelation intervention	Deferoxamine mesylate	138-14-7	Iron chelation and ferroptosis inhibition experiments
Inflammatory regulation	Dexamethasone	50-02-2	Positive anti-inflammatory intervention control
Inflammatory regulation	Ibuprofen	15687-27-1	Research on inflammatory responses and COX pathway intervention
Blood-brain barrier injury	Sodium fluorescein	518-47-8	Evaluation of blood-brain barrier permeability
Apoptosis induction/control	Staurosporine	62996-74-1	Positive apoptosis inducer
Cell viability detection	MTT	298-93-1	Detection of cell viability and drug toxicity
Cell membrane injury detection	Propidium iodide (PI)	25535-16-4	Dead cell staining and membrane integrity detection
Protein thiol modification	N-Ethylmaleimide (NEM)	128-53-0	Blocks free thiols for oxidative modification research
Protein thiol modification	Iodoacetamide (IAA)	144-48-9	Thiol alkylation and sample processing for protein oxidative modification

9 Common Mechanistic Questions and Result Interpretation

9.1 What is the difference between the infarct core and the ischemic penumbra?

The infarct core has the most severe reduction in blood flow, rapid ATP depletion, and early, mostly irreversible cell death. The ischemic penumbra retains partial blood flow and metabolic activity. Cells in this region are functionally impaired but still potentially salvageable, making it the key target region for reperfusion therapy and neuroprotective research.

9.2 Why does reperfusion have both protective and injurious effects?

Reperfusion can restore oxygen and glucose supply and rescue the penumbra. However, damaged mitochondria, xanthine oxidase, and inflammatory cells can produce a burst of ROS after oxygen re-entry, leading to oxidative stress, blood-brain barrier disruption, and aggravated inflammation. Therefore, reperfusion outcomes depend on ischemia duration, microcirculatory status, and tissue antioxidant capacity.

9.3 Why does increased glutamate lead to neuronal death?

Excess glutamate overactivates NMDA and AMPA receptors, causing massive Ca²⁺ influx. Calcium overload activates proteases, phospholipases, nucleases, and nitric oxide synthase, and also causes mitochondrial injury, ultimately leading to excitotoxicity and cell death.

9.4 Is the inflammatory response in cerebral infarction always harmful?

No. Moderate early inflammation helps clear necrotic tissue and initiate repair, but excessive or sustained inflammation disrupts the blood-brain barrier, promotes leukocyte infiltration, releases ROS and pro-inflammatory factors, and expands penumbral injury. The role of inflammation should be interpreted according to time window, cell type, and tissue region.

9.5 How can ferroptosis and apoptosis be distinguished in cerebral infarction?

Apoptosis is mainly characterized by activation of the caspase cascade, Bax/Bcl-2 imbalance, and TUNEL positivity. Ferroptosis is characterized by iron-dependent lipid peroxidation, decreased GPx4, increased ACSL4, GSH depletion, and increased MDA/4-HNE. Mechanistic studies should include specific inhibitors or genetic interventions for validation.

9.6 Why should cerebral infarction research not evaluate only infarct area?

Infarct area only reflects the extent of tissue injury and cannot explain injury mechanisms or functional outcomes. With the same infarct volume, the degree of inflammation, blood-brain barrier disruption, white matter injury, neural network remodeling, and behavioral recovery may differ markedly. Therefore, molecular, histological, and behavioral indicators should be integrated for comprehensive evaluation.

The neuropathological mechanism of cerebral infarction is essentially a continuous cascade initiated by neurovascular unit imbalance after blood flow interruption. Vascular occlusion initiates ischemia and hypoxia, energy metabolism failure leads to disruption of ion homeostasis and excitotoxicity, and subsequent oxidative stress, inflammatory responses, blood-brain barrier disruption, and multiple forms of cell death jointly drive expansion of the infarct lesion. Establishing mechanistic research systems around ischemic penumbra protection, control of reperfusion injury, regulation of neuroinflammation, and intervention in cell death pathways is a key direction for understanding cerebral infarction progression and developing intervention strategies.

References

[1] Liebeskind DS. The concept of the ischemic penumbra. Stroke, 2002, 33(9): 2231–2236.

[2] Siesjö BK. Brain energy metabolism in relation to ischemia and infarction. Ann Neurol, 1981, 10(Suppl 1): 10–16.

[3] Myers RE, Yamaguchi S, Ginsberg MD, et al. Relationship between lactic acidosis and ischemic brain damage. Stroke, 1977, 8(1): 48–54.

[4] Raichle ME. Brain energy metabolism: relation to function. In: Plum F, ed. Handbook of Physiology. Section 1: The Nervous System. Vol IV. Bethesda, MD: American Physiological Society, 1981: 643–674.

[5] Nicholls DG, Budd SL. Mitochondria and neuronal survival. Physiol Rev, 2000, 80(4): 1131–1155.

[6] Rothman SM, Olney JW. Glutamate and the pathophysiology of hypoxic-ischemic brain damage. Ann Neurol, 1986, 19(2): 105–111.

[7] Choi DW. Glutamate neurotoxicity and diseases of the nervous system. Neuron, 1988, 1(8): 623–634.

For more related articles, please see below:

[1] Middle Cerebral Artery Embolism (MCAO) Model in Rats by Wire Embolization Method