Distribution of heat shock protein 108 mRNA during the development of the chicken brain.

The developmental expression of heat shock protein 108 (HSP108) mRNA was mapped in chicken brain using in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR). RT-PCR showed that HSP108 mRNA increased from embryonic day 5 (E5) to 13 (E13), significantly decreased from E17 to E21 and then increased again at the adult stage. In situ hybridization showed that while intense HSP108 positive (HSP108+) signals were localized in the cerebellum from E7 to E14, the intensities of these signals were significantly decreased at E17. However, at the adult stage, HSP108 expression increased in a cell type dependent manner. A decrease in HSP108 mRNA expression during differentiation was also observed in an in vitro study of brain cells treated with nerve growth factor (NGF).

Protective effect of growth hormone on neuronal apoptosis after hypoxia-ischemia in the neonatal rat brain.

Recent studies have shown that growth hormone (GH) can reduce neuronal loss after hypoxic-ischemic injury (HI) in neonatal and juvenile rat brains. Here, we investigated whether GH exerts its neuroprotective role through an anti-apoptotic effect in neonatal rat brains damaged by severe HI. Gross and histological observations showed that the extent of brain damage was found to be reduced in GH-treated brain at E7 after injury. In a terminal transferase-mediated dUTP nick-end-labeling (TUNEL) study, TUNEL-positive apoptotic cells were localized only at the damaged region in animals treated with saline, which was confirmed by an electron microscopy. In an immunohistochemical study with anti-bcl-2, -bax, -bad, -neuronal nitric oxide synthase (nNOS), -inducible NOS (iNOS) and -endothelial NOS (eNOS) antibodies, we observed that bax, bad, iNOS and eNOS were elevated in the saline-treated group. This study thus suggests that the protective role of GH against HI injury is mediated thorough an anti-apoptotic effect, which offers the possibility of a GH application for the treatment of neonatal HI encephalopathy.

Immunocytochemical study on the distribution of c-myb in the central nervous system of the transgenic mice expressing a human copper/zinc superoxide dismutase mutation.

Although our previous study showed the constitutive expression of c-myb in neurons, suggesting that this gene might be involved in the normal function of these cells, there were no reports on the expression pattern of c-myb under pathological conditions. In the present study, we first investigated the changes in c-myb immunoreactivities (IRs) in the central nervous system of the transgenic mice expressing a human copper/zinc superoxide dismutase (Cu/Zn SOD) mutation. The distribution of c-myb was enhanced in the various brain regions of transgenic mice expressing a mutated human Cu/Zn SOD gene. Immunohistochemistry showed intensely stained c-myb IR glial cells with the appearance of astrocytes within the various brain regions of transgenic mice such as the gray matter of the midbrain, medulla oblongata and spinal cord. Even though the exact functions of c-myb in the normal and pathological states were not clearly revealed until now, we think that the increase in c-myb expression in the mutant mice could be due to the compensate mechanism of the astrocytes for the reduced defence against superoxide toxicity because the only known function of c-myb was its correlation with the prevention of programmed cell death, which could be deduced from the previous studies.

Ultramicroscopical immunolocalization of PAX6 in the adult chicken retina.

Cell type-specific PAX6 protein expression was examined in all retinal layers of the normal chicken retina. The most intense PAX6 immunostaining was found in the ganglion cell and inner nuclear layers, and in lower amounts in the optic nerve fiber, the inner plexiform and the photoreceptor layers. PAX6 immunostaining was variable in terms of its subcellular localization, even within one cell. PAX6 immunostaining was mainly localized in nuclear heterochromatin of the ganglion cell and inner nuclear layers whereas in the outer nuclear layer, PAX6 immunostaining was only observed in the intercellular space and the cytoplasm. In photoreceptors, the myoid portion of the inner segment showed PAX6 immunostaining, but the ellipsoid portion and the outer segment did not. The ultrastructural distribution pattern of PAX6 in the adult chicken retina suggests that normal expression of PAX6 is variable even in subcellular structures in the same cell type.

Heat shock protein 108 mRNA expression during chicken retina development.

In a developmental study on the expression of heat shock protein 108 (HSP108) mRNA in the chicken retina, we found different spatial and temporal expressions of HSP108 mRNA in each retinal layer. While intense HSP108 signals were found in the retina neuroblast layer at embryonic day 5 (E5), the ganglion cell population (GC), inner nuclear layer (IN) and pigment epithelium (PE) showed HSP108 expression at E9. At E14, HSP108 signals were reduced versus the previous stages even though signals were still detected in the GC, the IN, the outer nuclear layer and the PE. HSP108 signals were still detectable at the E21 stage, although each retinal layer showed a much differentiated morphology and diminished signal intensity. These results suggest that HSP108 expression might be developmentally regulated throughout eye organogenesis and that it plays a role in ocular development.