Reversible focal ischemia model in the rat: correlation of somatosensory evoked potentials and cortical neuronal injury.
Somatosensory evoked potentials (SEPs) are valuable in experimental stroke studies, but only a few reports have dealt with small rodent models. Our experiments aimed to reproduce SEP monitoring during reversible middle cerebral artery occlusion (MCAo) in a surgical model of open craniotomy and vessel manipulations in the rat. The changes of median nerve SEPs were correlated to the degree of local cortical neuronal injury in the forelimb area. Based on a pilot group (n = 11) both parameters were examined at 2 h after reperfusion in a subsequent study with increase of MCAo time from 1 (n = 7) to 2 h (n = 7); 5 rats were sham operated. A significantly delayed and incomplete recovery of SEPs, expressed as a percentage of the mean preocclusion values was observed with 2 h compared to 1 h MCAo (20.8% versus 6.0% change in the latency and 59.5% versus 2.2% in the amplitude of the primary cortical response). The functional outcome was found to correlate consistently with the degree of neuronal damage in 1 and 2 h reversible MCAo (2.5% versus 79.2% severely damaged neuronal types III and IV). Our findings suggest, that 2 h MCAo followed by 2 h reperfusion produces a submaximal neuronal injury and partial electrical recovery in the periphery of the occluded vascular territory and could be therefore used as a reliable model for assessment of cerebroprotective drug efficacy.
Marinov
M
M
Department of Neurosurgery, Faculty Alexander Hospital, Higher Medical School, Sofia, Bulgaria.
Schmarov
A
A
Natschev
S
S
Stamenov
B
B
Wassmann
H
H
D000818:Animals; D002536:Cerebral Arteries; D002540:Cerebral Cortex / Q000473:pathology / Q000503:physiopathology*; D004195:Disease Models, Animal; D005073:Evoked Potentials, Somatosensory; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D009474:Neurons / Q000473:pathology / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015424:Reperfusion; D013997:Time Factors