RESUMO
OBJECTIVE@#To improve the classical 4-vessel occlusion (4VO) model established by Pulsinelli and Brierley.@*METHODS@#Thirty-two male SD rats were randomized into sham operation group, I4VO-Con10 group, I4VO-Int10 group and I4VO-Int15 group. The sham surgery group underwent exposure of the bilateral vertebral arteries and carotid arteries without occlusion to block blood flow. The I4VO-Con10 group experienced continuous ischemia by occluding the bilateral vertebral arteries and carotid arteries for 10 minutes followed by reperfusion for 24 hours. The I4VO-Int10 and I4VO-Int15 groups were subjected to intermittent ischemia. The I4VO- Int10 group underwent 5 minutes of ischemia, followed by 5 minutes of reperfusion and another 5 minutes of ischemia, and then reperfusion for 24 hours. The I4VO-Int15 group experienced 5 minutes of ischemia followed by two cycles of 5 minutes of reperfusion and 5 minutes of ischemia, and then reperfusion for 24 hours. The regional cerebral blood flow (rCBF) was monitored with laser Doppler scanning, and survival of the rats was observed. HE staining was used to observe hippocampal pathologies to determine the optimal method for modeling. Another 48 rats were randomized into 6 groups, including a sham operation group and 5 model groups established using the optimal method. The 5 I4VO model groups were further divided based on the reperfusion time points (1, 3, 7, 14, and 28 days) into I4VO-D1, I4VO-D3, I4VO-D7, I4VO- D14, and I4VO- D28 groups. Body weight changes and survival of the rats were recorded. HE staining was used to observe morphological changes in the hippocampal, retinal and optic tract tissues. The Y-maze test and light/dark box test were used to evaluate cognitive and visual functions of the rats in I4VO-D28 group.@*RESULTS@#Occlusion for 5 min for 3 times at the interval of 5 min was the optimal method for 4VO modeling. In the latter 48 rats, the body weight was significantly lower than that of the sham-operated rats at 1, 3, 7, 14 and 28 days after modeling without significant difference in survival rate among the groups. The rats with intermittent vessel occlusion exhibited progressive deterioration of hippocampal neuronal injury and neuronal loss. Cognitive impairment was observed in the rats in I4VO-D28 group, but no obvious ischemic injury of the retina or the optic tract was detected.@*CONCLUSION@#The improved 4VO model can successfully mimic the main pathological processes of global cerebral ischemia-reperfusion injury without causing visual impairment in rats.
Assuntos
Ratos , Masculino , Animais , Ratos Sprague-Dawley , Isquemia Encefálica , Infarto Cerebral , Traumatismo por Reperfusão , Peso CorporalRESUMO
ObjectiveTo investigate the effects of dopamine receptor agonist pramipexole and levodopa on emotion and cognition, and mitochondrial membrane potential of rats after global cerebral ischemia-reperfusion injury. MethodsA total of 80 male Sprague-Dawley rats were divided into sham group (n = 20), model group (n = 20), pramipexole group (n = 20) and combined group (n = 20). The latter three groups were used to prepare the model of global cerebral ischemia-reperfusion injury with Pulsinelli's four-vessel occlusion. The pramipexole group was intraperitoneally injected pramipexole 0.5 mg/kg once a day, while the combined group was injected levodopa 50 mg/kg and pramipexole 0.5 mg/kg, for 14 days. Five rats in each group were tested with open field test three, seven and 14 days after modeling; five were tested with Y-maze test seven and 14 days after modeling; five were detected mitochondrial membrane potential three, seven and 14 days after modeling; and five were observed under Nissl's staining14 days after modeling. ResultsCompared with the model group, the number of entries into the central zone (P < 0.05), total distance travelled (P < 0.05) and average velocity (P < 0.05) in the open field test increased in the pramipexole and combined groups seven and 14 days after modeling, duration spent in the central zone increased in the pramipexole and combined groups seven days after modeling (P < 0.05); the rate of spontaneous alternation of Y-maze test increased in the pramipexole and combined groups 14 days after modeling (P < 0.05); mitochondrial membrane potential in hippocampus increased in the pramipexole and combined groups seven and 14 days after modeling (P < 0.05), and it was less in the pramipexole group than in the combined group 14 days after modeling (P < 0.05); and the number of surviving neurons in the hippocampal CA1 increased in the pramipexole and combined groups 14 days after modeling (P < 0.05). ConclusionPramipexole may improve emotion and cognition of rats after global cerebral ischemia-reperfusion injury, and it may be helpful for restoring mitochondrial membrane potential as combining with levodopa.