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HYPERGRAVITY-INDUCED ALTERATIONS OF GLIAL AND NEURONAL PROTEINS IN THE DEVELOPING RAT CEREBELLUM  E. M. Sajdel-Sulkowska^{1, 2} and G.-H. Li².  ¹Dept. Psychiatry, Harvard Medical School, ² Dept. Psychiatry, Brigham and Women’s Hospital, Boston, MA 02115.

     We previously reported that the developing rat cerebellum is vulnerable to hypergravity exposure, especially during a period of both granule and glial cell proliferation and neuronal migration. We hypothesized that the changes at the molecular level affecting cell-cell interactions contribute to retarded cerebellar development. To examine this hypothesis we measured the expression of glial and neuronal proteins involved in cell-cell interactions. The cerebellar lysates were prepared from Sprague-Dawley rat neonates exposed to continuous centrifugation at 1.5 G (HG; n=35) from gestational day (G) 11 to one of six postnatal time points: (P) 6, P9, P12, P18, P21, and P30; cerebellar lysates from stationary control (SC: n=34) neonates (housed under the same conditions) were used for comparison. Cerebellar size was maximally reduced at P6 in males (18.9%) and at P9 in females (19.2%), with a significant gender difference (ANOVA, P=0.048). Western blot analyses indicated gender-specific reduction of cerebellar proteins. In males maximal reduction of CD15 (26.7%), GFAP (43.1%) and NCAM (20.6%) were observed at P6; P9, and P9, respectively; in females CD15 (26.9%), GFAP (31.4%), and NCAM (31.4%) were most reduced at P6, P9 and P6. Northern blot analyses suggest that the reduction in cerebellar proteins in hypergravity-exposed neonates may be effected at the transcriptional level. Changes in the expression of these proteins are likely to affect cell-cell interaction which is critical to cell proliferation and migration, and thus contribute to abnormal cerebellar development under altered gravity.

     (Supported by NASA Grant NCC2-1042).