[The effect of fastigial nucleus electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia].

OBJECTIVE: To investigate the effect of cerebellar fastigial nucleus (FN) electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia.

METHODS: Thirty-five healthy male Wistar rats were divided into focal cerebral ischemia/reperfusion group (I/R group, undergoing ischemia by embolism of middle cerebral artery for 3, 6 or 8 hours and then undergoing reperfusion for 24 hours, thus subdivided into I/R 3 hours, 6 hours, and 8 hours subgroups of 5 rats), focal cerebral ischemia/reperfusion plus FN electrical stimulation group (I/R-FN group, n = 15, undergoing FN electrical stimulation followed by focal cerebral ischemia/reperfusion as in the I/R group), and sham operation group (n = 5). Twenty-four hours after the reperfusion or sham operation, the rats were killed. The brain slices underwent Nissl's staining. Two slices of each rat were examined to observe the neuronal number and morphology, and the status or Nissl's staining, and make a scoring of the affected somatosensory cortex.

RESULTS: The survival rates of neurons of the I/R 3, 6 and 8 hours subgroups 3.2% +/- 11.3%, 2.6% +/- 4.5% and 3.8% +/- 3.2% respectively without a significant difference between any 2 subgroups (all P > 0.05). The scores of these 3 subgroups all reached the highest grade (4.0 +/- 0.0). The neuron survival rate of the I/R FN 3 hours subgroup was 64.2% +/- 11.3%, significantly higher than those or other I/R subgroup at the same time point (all P < 0.01), however, the neurons being obviously shrunken. The score of the I/R FN 3 hours subgroup 2.1 +/- 0.2, significantly lower than that of the I/R 3 hours subgroup (P < 0.01). The neuron survival rate of the I/R FN 6 hours subgroup was 32.8% +/- 6.5%, significantly higher than that of the I/R 6 hours subgroup (P < 0.05), however, the neurons being shrunken and irregular in shape. The score of the I/R FM subgroup was 3.0 +/- 0.0, significantly lower than that of the I/R 6 hours subgroup (P < 0.05). The I/R FN 8 hours subgroup showed a neuron survival rate of 4.1% +/- 3.5%, not significantly different from that of the I/R 9 hours subgroup (P > 0.05), and the same score as that of the I/R 8 hours subgroup. The sham operation group showed a survival rate of neurons of 96.9% +/- 17.3% and a score of 0.00 +/- 0.00.

CONCLUSION: FN electrical stimulation prolongs the therapeutic window of opportunity for intervention of focal cerebral ischemia. The complete recovery of survived neurons may need further interventions.