There is accumulating evidence, that ischemic preconditioning (PC) – a non-damaging ischemic challenge to the brain – confers a transient protection to a subsequent damaging ischemic insult. We established bilateral common carotid artery occlusion (BCCAO) as a preconditioning stimulus to induce early ischemic tolerance (IT) to transient focal cerebral ischemia (induced by middle cerebral artery occlusion, MCAO) in C57Bl6/J mice.
There is accumulating evidence, that ischemic preconditioning – a non-damaging ischemic challenge to the brain – confers a transient protection to a subsequent damaging ischemic insult. We have established bilateral common carotid artery occlusion as a preconditioning stimulus to induce early ischemic tolerance to transient focal cerebral ischemia in C57Bl6/J mice. In this video, we will demonstrate the methodology used for this study.
Ischemic stroke is a disease with a high mortality and an enormous socio-economic burden 1. Despite intensive experimental and clinical scientific efforts throughout recent decades, treatment options for acute ischemic stroke patients remain very limited 2. In contrast to that, increase in the percentage of elderly people in developed countries will dramatically increase incidences and prevalences of patients with ischemic stroke in the next decades 3. Therefore, there is a pressing need for new treatment strategies in patients with ischemic stroke.
One approach is to gain further understanding in mechanisms of endogenous adaptation of brain to cope with a damaging stimulus. This brain-derived neuroprotection is also known as ischemic preconditioning (PC) or ischemic tolerance (IT) and describes a phenomenon, in which a non-damaging noxious stimulus applied to the brain, induces a transient resistance against a subsequent damaging ischemic insult 4. IT occurs in two different time windows: early IT, which occurs within minutes to a few hours after PC and delayed IT, which needs a latency of a couple of hours to occur 4.
So far, research on IT in brain has focused on delayed IT. Much less is known on the mechanisms of early IT. The objective of this study is to establish bilateral common carotid artery occlusion (BCCAO) which is an established stimulus to induce delayed IT, as an adequate PC stimulus to induce early IT to transient focal cerebral ischemia (induced by middle cerebral artery occlusion, MCAO) in C57Bl6/J mice.
During both surgical procedures (BCCAO and MCAO), monitoring of cerebral blood flow (CBF) by laser Doppler flowmetry (LDF) was performed.
BCCAO was performed in anesthetized and spontaneously breathing mice. Both common carotid arteries (CCA) were exposed and occluded for 60 sec followed by 5 min of reperfusion. This BCCAO/reperfusion sequence was repeated twice. After surgery, mice recovered quickly and showed no signs of functional impairment. In order to rule out, that the BCCAO protocol described above did not result in delayed cell death in the brain, we performed a TdT-mediated dUTP-biotin nick end labelling (TUNEL) staining 72 hr after BCCAO (or sham surgery) in a separate group.
MCAO is a widely established model for induction of focal cerebral ischemia in rodents 5-7. The surgical procedures were carried out using standardized operating procedures (SOP) 8. After exposing left CCA, a silicon-covered monofilament was introduced into the distal CCA, advanced via the internal carotid artery (ICA) into the Circle of Willis until the anterior cerebral artery (ACA) and thereby, the origin of the middle cerebral artery (MCA) was occluded for a defined period of time. In this study, we used 45 min of MCAO, which typically results in an ischemic lesion in the MCA territory involving striatal and cortical brain areas.
In our study, we analyzed the temporal profile of early IT using BCCAO as the PC stimulus. Our data indicated, that the optimal time delay between BCCAO and MCAO to induce early IT is 30 min.
In this video, we will give a demonstration of both surgical procedures, i.e. BCCAO and MCAO.
In our study, we have shown that three sequences of BCCAO, each lasting for one minute and followed by reperfusion for five minutes, are an adequate ischemic PC stimulus to induce early IT.
Furthermore, we have demonstrated that the preconditioning protocol used is a safe and minor invasive procedure with no noteworthy postoperative morbidity, no signs of apoptosis in brain and no mortality. Several different preconditioning protocols have been described previously 6-7,12. Others …
The authors have nothing to disclose.
Name of the instrument | Company | Catalogue number/model |
Binocular surgical microscope | Zeiss | Stemi 2000 C |
Light source for microscope | Zeiss | SteREO CL 1500 ECO |
Heating pad with rectal probe | FST | 21061-10 |
Stereotactic frame | David Kopf | Model 930 |
Scissors | FST | 91460-11 |
Dumont forceps #5 | FST | 11251-10 |
Dumont forceps #7 | FST | 11271-30 |
Mircovascular clamp | FST | 00398-02 |
Clamp applicator | FST | 00072-14 |
Springscissors | FST | 15372-62 |
Needle holder | FST | 12010-14 |
Needles | Feuerstein, Suprama | BER 562-20 |
5-0 silk suture | Feuerstein, Suprama | |
7-0 silk suture | Feuerstein,Suprama | |
8-0 silk suture | Feuerstein, Suprama |