Effect of stimulation of cerebellar fastigial Nucleus on focal Cerebral Infaretion in Rat

ABSTRACT

Electrical stimulation of the cerebellar fastigial nucleus(FN) increases cerebral blood flow(CBF) and reduces brain damage after focal cerebral ischemia. The authors studied whether the neuroprotection elicited from electrical stimulation of the cerebellar FN is attibutable to the elevation in regional CBF(rCBF) or reduction in release of excitatory amino acid sprague-Dawley rats were anesthtized with a mixture of halothane(3% for the indurction and 1% for maintenance) and oxygen and artificially ventilated through a tracheal cannula. Arterial pressure, blood gases and body temperature were monitored. The middle cerebral artery(MCA) was occluded distal to the lenticulostriate branches. The FN was then for 2 hours, over the regions corresponding to the ischemic core and penumbra. Postiischemic release of glutamate and aspartate were measured by microdialysis for 2 hours at the same site of measurement of rCBF. Infarct volume was determined 8 hours later in 2,3,5-triphenyl tetrazolium chloride(TTC)-stained sections FN stimulation(n=12) increased mean arterial pressure by 28+/-16mmHg. In nonstimulated control rats(n=12), mean AP was not changed significantly during the experimental procedures. Compared with nonstimulated animal, stimulation of FN for 1 hour following MCA occlusion siginficantly increased rCBF in ischemic core and penumbra by 53.6% and 67.6% respectively. And the volume of infarction decreased by 42% at 8 hours after MCA occlusion. The concentration of glutamate and aspartate in ischemic core after MCA occlusion increased both in the control group(to 12.2+/-3.3 folds and 10.4+/-4.1 folds respectively) and in the stimulation group(10.5+/-2.8 and 11.2+/-4.1 folds, respectively). The concentration of glutamate and aspartate in penumbra did change significantly neither in the control group(to 2.5+/-1.3 folds and 1.8+/-0.6 folds respectively) nor in the stimulation group(1.9+/-0.5 folds and 2.1+/-0.4 folds, respectively). There was no significant difference between the two groups.