Chikako Kinoshita

Short- and long-term effects of low-dose prenatal X-irradiation in mouse cerebral cortex, with special reference to neuronal migration

Abstract To elucidate the short- and long-term effects of ionizing radiation on cell migration in the developing cerebral cortex, we labeled proliferating cells on day 14 of gestation of mice with bromodeoxyuridine (BrdU) followed by a single exposure to 0.1–1 Gy of X-rays. The brains of embryos on day 17 and offspring at 2, 3 and 8 weeks after birth were processed for BrdU immunohistochemistry to trace the movements of BrdU-labeled cells. The location of BrdU-labeled neurons in the cerebral cortex was quantitatively analyzed between irradiated animals and non-irradiated controls. We have demonstrated that the initial migration of BrdU-labeled cells from the matrix cell zone towards the cortical plate during embryonic periods was decelerated when exposed to X-rays of 0.25, 0.5 and 1 Gy on embryonic day 14, and that aberrantly placed neurons in the cerebral neocortex were noted in younger animals that were irradiated prenatally, whereas such derangement was less pronounced in mature animals. These observations suggest that some modification process might have occurred during the postnatal period.

Spatial and temporal patterns of distribution of the gap junction protein connexin 32 and 43 during histogenesis of mouse cerebral cortex

The distribution of gap junction proteins, connexin(Cx) 32 and 43 in developing mouse cerebral cortex was studied with silver amplification immunoperoxidase technique. Cx 43 immunoreactivity was discerned between matrix cells in the telencephalon from the embryonic 10-day-old(E10) and remained positive throughout the embryonic period, although it became more pronounced in the deeper part of the matrix cell zone with time of development, hi addition neurons located in the cortical plate as well as in the intermediate zone expressed Cx 43. Sparse Cx 32 immunoreactivity was seen in neuroepithelium of E10, and between neurons during later period of development.

A combined staining method for argyrophilic nucleolar organizer regions and for glial fibrillary acidic protein in astrocytes of human brain.

SummaryDifferent protocols are described for the combined staining method by which argyrophilic nucleolar organizer region sites can be evaluated in human astrocytes that are immunoreactive for glial fibrillary acidic protein. Among the four protocols studied, the following method was superior to others in terms of unambiguous visualization of the regions in glial fibrillary acidic protein-positive astrocytes; the first step was immunostaining for the protein with a blue colour reaction of alkaline phosphatase, followed by sequential colloidal silver staining for the regions.By this double staining method, we have demonstrated that the reactive astrocytes found in white matter around the metastatic lesion of carcinoma and the infarction, contain more argyrophilic nucleolar organizer regions in terms of the count as well as the area than glial fibrillary acidic protein-positive astrocytes present in the white matter of the normal brain.In conclusion, the double staining may provide valuable information on the cellular activity of astroglia when performed on routine formalin-fixed paraffin sections of the human brain.