A BRAIN-TUMOR MODEL UTILIZING STEREOTAXIC IMPLANTATION OF A PERMANENTCANNULA

A tumor model involving stereotactically implanted culture-reared tumo r cells is presented. Stainless steel cannulas were stereotactically a nd permanently implanted into the caudate nucleus of 30 rats. The anim als were separated into two groups. In Group I, 15 animals received a 10-mul injection containing 10(6) C6 glioblastoma cells (five rats), 1 0(6) Walker 256 breast carcinoma cells (five rats), or cell medium (fi ve rats). The coordinates were A(+1.5), L(+3.0), and DV(-5.0). In Grou p II, the coordinates were changed to A(+1.0), L(+3.0), and DV(-5.0) a nd the same number of rats received a 1-mul injection containing 10(5) cells of each tumor in an attempt to produce more focal tumors. Two w eeks after implantation, brain sections were stained with cresyl viole t and a subset was stained for glial fibrillary acidic protein (GFAP). A computerized morphometric analysis system was used to quantify tumo r size. In Group I, the mean C6 tumor areas (+/-standard error of the mean) at specific coordinates were (in sq mm): A(+4.7) 0.4 +/- 0.2; A( +3.7) 3.5 +/- 1.1; A(+2.7) 5.7 +/- 1.7; A(+1.7) 9.5 +/- 2.3; A(+0.7) 7 .5 +/- 3.2; A(-0.3) 3.7 +/- 2.9; and A(-1.3) 0.3 +/- 0.3. A nearly ide ntical tumor mass and extension into the brain was produced in rats in jected with Walker 256 cells. Similar C6 tumor areas were indicated in adjacent sections stained with cresyl violet and GFAP. Tumor was foun d in the caudate nucleus in all 10 rats, but not in the nucleus accumb ens, fornix, or hippocampus. In Group II animals, tumor magnitude and extension into the brain were greatly reduced. The 10(6) cells in the 10-mul volume was the most reliable tumor load for obtaining uniform t umors in different animals. The similarity of tumor distribution acros s different animals was indicated by the low variance of tumor area at specific anteroposterior coordinates. Reproducible and well-circumscr ibed caudate nucleus tumors were produced using this stereotactic proc edure.