This review is directed at understanding how neuronal death occurs in two distinct insults, global ischemia and focal ischemia. These are the two principal rodent models for human disease. Cell dea...

Ischemic Cell Death in Brain Neurons

Ischaemia-reperfusion injury occurs when the blood supply to an organ is disrupted and then restored, and underlies many disorders, notably heart attack and stroke. While reperfusion of ischaemic tissue is essential for survival, it also initiates oxidative damage, cell death and aberrant immune responses through the generation of mitochondrial reactive oxygen species (ROS). Although mitochondrial ROS production in ischaemia reperfusion is established, it has generally been considered a nonspecific response to reperfusion. Here we develop a comparative in vivo metabolomic analysis, and unexpectedly identify widely conserved metabolic pathways responsible for mitochondrial ROS production during ischaemia reperfusion. We show that selective accumulation of the citric acid cycle intermediate succinate is a universal metabolic signature of ischaemia in a range of tissues and is responsible for mitochondrial ROS production during reperfusion. Ischaemic succinate accumulation arises from reversal of succinate dehydrogenase, which in turn is driven by fumarate overflow from purine nucleotide breakdown and partial reversal of the malate/aspartate shuttle. After reperfusion, the accumulated succinate is rapidly re-oxidized by succinate dehydrogenase, driving extensive ROS generation by reverse electron transport at mitochondrial complex I. Decreasing ischaemic succinate accumulation by pharmacological inhibition is sufficient to ameliorate in vivo ischaemia-reperfusion injury in murine models of heart attack and stroke. Thus, we have identified a conserved metabolic response of tissues to ischaemia and reperfusion that unifies many hitherto unconnected aspects of ischaemia-reperfusion injury. Furthermore, these findings reveal a new pathway for metabolic control of ROS production in vivo, while demonstrating that inhibition of ischaemic succinate accumulation and its oxidation after subsequent reperfusion is a potential therapeutic target to decrease ischaemia-reperfusion injury in a range of pathologies.

/pdf/ischaemic-accumulation-of-succinate-controls-reperfusion-594jb4hyx1.pdf

Ischaemic accumulation of succinate controls reperfusion injury through mitochondrial ROS.

An accurate, reproducible method for determining the infarct volumes of gray matter structures is presented for use with presently available image analysis systems. Areas of stained sections with optical densities above that of a threshold value are automatically recognized and measured. This eliminates the potential error and bias inherent in manually delineating infarcted regions. Moreover, the volume of surviving normal gray matter is determined rather than that of the infarct. This approach minimizes the error that is introduced by edema, which distorts and enlarges the infarcted tissue and surrounding white matter.

https://journals.sagepub.com/doi/pdf/10.1038/jcbfm.1990.47

A Semiautomated Method for Measuring Brain Infarct Volume

Ischaemic accumulation of succinate controls reperfusion injury through mitochondrial ROS

Background and Purpose The purpose of the present study was to evaluate a modified method of intraluminal suture occlusion of the middle cerebral artery (MCA) on the volume of brain infarction and on neurobehavioral function in rats subjected to a temporary focal ischemic insult. Methods Male Sprague-Dawley rats were anesthetized with halothane and subjected to 60 minutes or 2 hours of temporary MCA occlusion (MCAo) by an intraluminal thread. In one group of rats, the suture was coated with poly-l-lysine, while in a second group, a conventional uncoated suture was used. Behavioral function was evaluated at 50 to 60 minutes after occlusion and during a 3-day period after MCAo. Three days after MCAo, brains were perfusion-fixed and infarct volumes were measured. Results In rats with 60-minute MCAo, only 3 of 7 animals with uncoated sutures had infarcts, whereas in the group with poly-l-lysine–coated sutures, all rats (n=7) exhibited infarction (P=.009, Fisher's exact test). With 2 hours of MCAo, total infar...

Middle Cerebral Artery Occlusion in the Rat by Intraluminal Suture Neurological and Pathological Evaluation of an Improved Model

A method for the volumetric assessment of early cerebral infarction, together with its statistical and biological validation, is described. In halothane anaesthetised rats the stem of the right middle cerebral artery was occluded and 3 hours later (with full monitoring of respiratory and cardiovascular status) the animals were killed by perfusion fixation. In normotensive normocapnic animals the volume of infarction was 52 +/- 4 mm3 in the cerebral cortex and 21 +/- 1 mm3 in the corpus striatum. The reproducibility of the volumetric assessment was found to be excellent (coefficient of correlation 0.995 on 18 replicate measurements). The minimum number of stereotactic levels which must be assessed to yield accurate volumetric measurements of infarction is 8. The method is sensitive at detecting alterations in the amount of infarction. For example, it can readily detect the increase in amount of structural damage in cerebral cortex following a transient episode of hypotension. This approach allows an objective assessment of drug therapy and management strategies in the treatment of cerebral infarction.

https://jnnp.bmj.com/content/jnnp/50/4/402.full.pdf

Quantitative assessment of early brain damage in a rat model of focal cerebral ischaemia.

SUMMARY A methodforthevolumetric assessment ofearly cerebral infarction, together withits statistical andbiological validation, isdescribed. Inhalothane anaesthetised ratsthestemofthe right middle cerebral artery was occluded and3hours later (with full monitoring ofrespiratory and cardiovascular status) theanimals were killed byperfusion fixation. Innormotensive normocapnic animals thevolume ofinfarction was 52+ 4mm3 inthecerebral cortexand21+ 1 mm3 inthe corpusstriatum. Thereproducibility ofthevolumetric assessment was foundtobeexcellent (coefficient ofcorrelation 0995on 18replicate measurements). Theminimumnumberofstereotactic levels which mustbeassessed toyield accurate volumetric measurementsofinfarction is8. Themethodissensitive atdetecting alterations intheamountofinfarction. Forexample, itcan readily detect theincrease inamountofstructural damageincerebral cortexfollowing a transient episode ofhypotension. This approach allows an objective assessment ofdrugtherapy andmanagementstrategies inthetreatment ofcerebral infarction. Numerousattempts havebeenmadetoproduce experimentally anischaemic lesion resembling that seeninman.Oneofthemostcommonly usedmethodshasbeentoocclude themiddle cerebral artery in various experimental animals`6 inthebelief that proximal occlusion ofthis artery isequivalent toa large focal cerebral infarct inman. We havedeveloped atechnique foroccluding the middle cerebral artery (MCA)intherat7 whichhas proved useful forcorrelating local cerebral blood flow8 anddysfunction oftheblood-brain barrier9 withhistological evidence of ischaemic brain damage. 10 Inthis paper wedetail arigorous meansformeasuring thevolume ofearly cerebral infarction inthe ratafter occlusion ofthemiddle cerebral artery. This method, withits statistical validation, together witha demonstration ofits ability tomeasure changes inthe amountofstructural damage invarious experimental conditions, isdescribed. Someofthisdatahas appeared previously inabstract form."

Quantitative assessment ofearly brain damage ina rat modeloffocal cerebral ischaemia

Focal cerebral ischemia produces heterogeneous alterations in the cerebral circulation and metabolism, which eventually lead to the development of ischemic brain damage. It is not, however, in the period after irreversible brain damage is established that brain water is increased. Early ischemic oedema seems rather to be a reversible functional event, in which a change in the permeability of the blood-brain barrier (BBB) to cations is involved through unknown mechanisms of brain capillary function. In the later stage, however, when gross changes in the BBB are induced, the development of brain oedema may well be linked with that of ischemic brain damage. Therefore, an important question at this stage is whether brain oedema itself has neuropathologic consequences. Since no correlative investigations have so far been published, we report here topographical alterations and the correlation between IBD and oedema formation following occlusion of the middle cerebral artery (MCA) in the rat.

T Shigeno

Papers

Quantitative assessment of early brain damage in a rat model of focal cerebral ischaemia.

Quantitative assessment ofearly brain damage ina rat modeloffocal cerebral ischaemia

Cerebrovascular Permeability and Ischemic Brain Damage Following MCA Occlusion in the Rat