1222 Immunohistochemical analysis of developmental stage of apoptotic granule neurons in neonatal rat cerebellum

Sl55

1221 Department

DEPOLARIZATION-DEPENDENT SURVIVAL OF CEREBELLAR GRANULE CELLS ACCOMPANIED BY ACTIVATION OF Ca2+TURNOVER AND ENDOCYTOSIS . of Biology, Graduate School of Science, Osaka University, Osaka 560, Japan

KEIGO KOHARA, KEIKO TOMINAGA, AKIHIKO OGURA The rat cerebellar granule cells survive in vitro when maintained in a medium containing high concentration of KCl, but die when maintained under low KCl. We reported that both Ca2+ influx and Ca2+ efflux were activated under the high KC1 condition. Taking a possibility that an increased uptake of trophic factors might be resulted from high Ca 2+ turnover, we assayed the activity of endocytosis by uptaking rates of horseradish peroxidase and fluoresent dye FMl-43 applied extracellularly. The endocytotic aactivity was significantly higher under high KC1 condition.

1222

Immunohistochemical analysis of developmental stage of apoptotic granule neurons in neonatal rat cerebellum Div. of Cell Biol., Inst. for Comprehens. Med. Sci., Fujita Health Univ., Toyoake, Aichi 470-11. Japan Masahiko Tanaka, Tohru Marunouchi Some granule neurons naturally fall into apoptosis in the external granular layer (EGL) of developing cerebellum. We analyzed the developmental stage-specificity of this apoptosis using double staining by in situ nick end labeling and immunohistochemistry against three proteins expressed at the specific stages of granule neuron development. In postnatal rat cerebellum, 66.5% of apoptotic EGL neurons expressed proliferating cell nuclear antigen. On the other hand, 22.1 and 20.3% of apoptotic EGL neurons existed in the postmitotic and premigratory zone defined by expression of TAG-l and 440 kDa ankyrinB, respectively. Thus, proliferative granule neurons fall into apoptosis more frequently than postmitotic granule neurons in EGL of developing cerebellum. This suggests developmental stage-specific mechanisms of apoptosis of cerebellar granule neurons.

1223 Department

Glucocorticod

receptor immunoreactivity

of Anatomy, Kyoto Prefe4ctural

with granule cell death in the rat hippocampus

University of Medicine

Zhongting Hu, Kazunari Yuri, Hitoshi Ozawa, Mitsuhiro Kawata Removal of endogenous glucocorticoids after adrenalectomy (ADX) results in selective cell death within the hippocampal granule cell layer. In this study, we analyzed the relationship between glucocorticoid receptor (GR), whose localization was detected by immunohistochemistry (IR), and the granule cell death in the rat hippocampus. Our results demonstrated that accompanied by the complete loss of GR immunoreactivity (IR) after short-term ADX, many degenerating cells were found in the granule cell layer. Corticosterone replacement to the acute ADX-rats restored the GR-IR and prevented granule cell death. Three to five months after ADX, 20-30% rats showed granule cell loss and remaining 80% displayed normal granule cell layer. Those rats with granule cell loss showed complete loss of GR-IR within the granule cell nuclei but those without granule cell loss displayed weak to normal GR-IR. These results suggested that loss of GR-IR is closely linked to the ADX-induced granule cell death.