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Mechanisms that result in damage during and following cerebral ischemia
1Saskatchewan Stroke Research Centre, Saskatoon, Canada.
Abstract:
The destructive mechanisms associated with stroke are initiated by activation of glutamate receptors resulting in elevated intracellular Ca2+ and reactive oxygen species (ROS) formation. Three major approaches have been investigated to ameliorate ischemia-induced brain damage: (i) interfering with the excitatory action of glutamate; (ii) preventing intracellular accumulation of Ca2+; and (iii) preventing the destructive actions of reactive oxygen species (ROS). Interference with glutamate action can be achieved by: (i) facilitating mechanisms that maintain membrane potentials; (ii) blocking glutamate receptors; and (iii) inhibiting transmitter glutamate synthesis. Prevention of intracellular Ca2+ accumulation may be achieved by: (i) blocking Ca2+ channels; and (ii) facilitating endogenous Ca2+ homeostatic mechanisms. Destructive actions of ROS can be minimized by: (i) administration of ROS-scavenging drugs; (ii) upregulating endogenous ROS-scavenging mechanisms; and (iii) preventing leukocyte invasion of the affected brain tissue. Current therapies that have arisen out of animal experimentation have not met expectations due, mainly to actions of the drugs outside the lesion site. For future research, we suggest: (i) exploring the ability of compromised blood-brain barrier to specifically target therapeutic drugs to the site of lesion; (ii) preventing inflammation by preventing leukocyte infiltration; (iii) identifying signal transduction mechanisms that upregulate neuronal Ca2+ homeostatic mechanisms; and (iv) identifying means that will upregulate endogenous ROS-scavenging mechanisms. Past success in reducing the incidence of stroke has been due, to a great extent, to changes to lifestyle behavioural patterns. We predict that future success in decreasing the morbidity associated with stroke will, to a certain extent, also be due to long-term behavioural changes. It seems possible that simple dietary changes may enable the CNS to be better able to cope with ischemic insults by augmenting ROS-scavenging mechanisms, down-regulating pro-inflammatory responses and increasing Ca(2+)-homeostatic mechanisms.
Insights
Stroke-induced brain damage involves glutamate, calcium, and reactive oxygen species (ROS). Future therapies may involve targeted drug delivery, inflammation control, and lifestyle changes like diet to enhance brain resilience.
Area of Science:
- Neuroscience
- Biochemistry
- Pharmacology
Background:
- Stroke-induced brain damage is primarily driven by glutamate receptor activation, leading to elevated intracellular calcium (Ca2+) and reactive oxygen species (ROS) formation.
- Current therapeutic strategies focus on mitigating these factors: interfering with glutamate action, preventing Ca2+ accumulation, and neutralizing ROS.
- Existing treatments derived from animal models have shown limited efficacy due to off-target drug effects.
Purpose of the Study:
- To review the mechanisms of ischemic brain damage and current therapeutic approaches.
- To identify promising future research directions for stroke treatment.
- To explore the potential role of lifestyle modifications, such as dietary changes, in stroke prevention and recovery.
Main Methods:
- Review of existing literature on stroke pathophysiology and therapeutic interventions.
- Analysis of the limitations of current stroke therapies.
- Identification of novel therapeutic targets and strategies for future research.
Main Results:
- Established pathways of stroke-induced neuronal injury involve glutamate excitotoxicity, Ca2+ overload, and ROS generation.
- Limitations in current therapies stem from a lack of lesion-specific drug targeting and off-target effects.
- Promising future directions include exploiting a compromised blood-brain barrier for targeted drug delivery, inhibiting inflammation, and enhancing endogenous neuroprotective mechanisms.
Conclusions:
- Future stroke therapies require improved drug targeting to the lesion site and modulation of inflammatory responses.
- Enhancing endogenous neuronal Ca2+ homeostasis and ROS-scavenging mechanisms are critical targets.
- Long-term behavioral changes, particularly dietary modifications, hold potential for increasing central nervous system (CNS) resilience to ischemic insults.