Abstract
Hemorrhage around the internal capsule (IC) induced relatively sever motor dysfunction with a relative small brain damage. We tried to make a new model of intracerebral hemorrhage with a small IC hematoma. Rats were injected type IV collagenase (1.4 μl of 1-200 U/ml) into the striatum near left IC. Behavioral function was evaluated for 7 days after the injection with five parameters: spontaneous rotation, hindlimb retraction, beam walk ability, forepaw grasp and methamphetamine-induced rotation. Hematoxylin-eosin staining revealed that 7.5 U/ml is the optimal concentration, because higher concentrations caused too large tissue damage and lower concentrations did not induce motor dysfunction. To confirm this, we labeled in advance primary motor neurons in the sensorimotor cortex with retrograde tracer Fluoro-Gold (FG: 1μl of 2% solution into the corticospinal tract (CST) of C 2-3 level), and then counted labeled-cells in the sensorimotor cortex every 0.5 mm sections (from 2.2 mm rostral to 1.3 mm caudal from bregma). Number of labeled neurons at 0.8 mm caudal to bregma was decreased to 79.7 ± 6.2% (n=4, p=0.016) of that of contralateral side at 14 day after the lesion compared to saline-treated group (n=3, 97.6 ± 2.7%). In addition, FG treatment into CST in C 2-3 after the lesion did not label ipsilateral motor neurons. Data suggest that collagenase injection into an area near IC with 1.4 μl of 7.5 U/ml induced a relative small brain damage with relatively bigger motor dysfunction resulting a good model of IC hemorrhage. [Jpn J Physiol 54 Suppl:S182 (2004)]
