3-DIMENSIONAL ANALYSIS OF VASOSPASTIC MAJOR CEREBRAL-ARTERIES IN RATSWITH THE CORROSION CAST TECHNIQUE

Background and Purpose Although mice, rats, and other small animals ar e commonly used for molecular biology research, their use in the evalu ation of cerebral vasospasm after subarachnoid hemorrhage is somewhat problematic because of the correspondingly small size of their cerebra l vessels. We have already reported that the corrosion cast technique was useful for evaluating newly formed cerebral vessels in neural graf ts in these small animals. In the present study we applied the corrosi on cast technique to the evaluation of hemolysate-induced cerebral vas ospasm in rats and performed three-dimensional analysis for comparison . The casting was done 10 minutes after the hemolysate injection, so t hat only acute ''vasospasm'' was assessed. Methods After withdrawal of 0.1 mL cerebrospinal fluid, 0.2 mt hemolysate (n=9) or saline (n=10) was injected into the cisterna magna of male Sprague-Dawley rats weigh ing between 300 and 350 g. Ten minutes later, perfusion of a semipolym erized casting medium was performed at an injection pressure of 100 to 120 mm Hg. The brains were immersed and corroded in 10% NaOH solution . After these procedures, the basilar artery as well as peripheral ves sels was analyzed morphologically with scanning electron microscopy. C onventional histological analysis with the use of paraffin-embedded se ction with hematoxylin-eosin staining was also performed, and the resu lts were compared with those for the corrosion cast methods. Results I n the saline-injected group, SEM showed that the inner surface of the basilar artery was smooth and the form of the endothelial cell was pri nted on the surface of the cast. In the hemolysate-injected group, the basilar artery showed an apparent vasospasm over its entire length, a nd corrugation was observed on the inner surface of the basilar artery in a three-dimensional fashion. Higher magnification revealed that th e nuclei of the endothelial cells were distorted. Local narrowing of t he basilar artery and vasospasm in the arteries of the anterior circul ation and in peripheral arteries were also observed. Measurement of th e inner diameter of the basilar artery showed 37.8% contraction in the hemolysate-injected group compared with the saline-injected group by the corrosion cast method. This degree of vasospasm was similar to tha t observed by the conventional histological method. Conclusions In thi s report we show that detailed three-dimensional observation in the ra t can be performed qualitatively and quantitatively with the corrosion cast technique. We conclude that this method derives an accurate meas urement of the diameter of rat major cerebral arteries and is more rel iable for analyzing vasospasm in rats than angiography and other conve ntional procedures.