Developmental brain abnormalities accompanied with the retarded production of S-100β protein in genetic polydactyly mice

Abstract

The homozygotes of a mouse strain with genetic polydactyly (Polydactyly Nagoya. Pdn) exhibit various brain malformations including exencephaly in about 20%. In the present report, the brains of homozygotes Pdn/Pdn which were not exencephalic were examined morphologically and biochemically. Homozygous newborn brains showed hydrocephaly, some gyri on the cerebral hemisphere, absence of the corpus callosum, absence of the commissura anterior, absence of the fornix and commissura fornicis, protuberance of the cortical tissue from the brain surface, and abnormal architecture of the hippocampus. An irregular mass of olfactory nerve was observed on the cribriform plate, and the olfactory bulb was deficient. From these findings, we considered Pdn/Pdn as a kind of arhinencephalic mouse. Nervous tissue-related proteins, S-100α, S-100β, creatine kinase B (CK-B), neuron-specific γ-enolase, guanosine triphosphate binding proteins (G o, G i2 and Gβ) were immunoassayed in the cerebrum of Pdn/Pdn embryos and newborns. Among the protein analysed, only S-100β of Pdn/Pdn showed a significantly lower level than that of +/+ cerebrum during the observation period. The newborn brains were examined immunohistochemically using S-100α, S-100β, CK-B, G oα and NSE antibodies. We could find no differences in the staining patterns among the Pdn/ Pdn, Pdn/+ and +/+ brains.