Astrocytes, Microglia, and Parkinson's Disease

Astrocytes and microglia support well-being and well-function of the brain through diverse functions in both intact and injured brain. For example, astrocytes maintain homeostasis of microenvironment of the brain through up-taking ions and neurotransmitters, and provide growth factors and metabolites for neurons, etc. Microglia keep surveying surroundings, and remove abnormal synapses or respond to injury by isolating injury sites and expressing inflammatory cytokines. Therefore, their loss and/or functional alteration may be directly linked to brain diseases. Since Parkinson's disease (PD)-related genes are expressed in astrocytes and microglia, mutations of these genes may alter the functions of these cells, thereby contributing to disease onset and progression. Here, we review the roles of astrocytes and microglia in intact and injured brain, and discuss how PD genes regulate their functions.

Paying attention to optic nerve injury disease and optic nerve regeneration study / 中华实验眼科杂志

Glaucoma,optical neuritis and trauma are optic nerve injury-related diseases.These ocular diseases cause irreversible damage of the vision and even blindness.The study on optic nerve regeneration is a powerful approach for rescuing vision and improving the quality of life of patients.Therefore,how to promote optic nerve regeneration is always the focus in ophthalmology.In recent years,great progression has achieved by modulation of cellular signal pathway,usage of glial cells,stem cells and neurotrophic factor,etc,which lays a basis for the treatment of optic nerve injury.Ophthalmologist should trace and participate in these researches to promote the development of regeneration medicine.This review summarizes these new approaches after discussing factors effecting optic nerve regeneration briefly and proposes questions to answer.

Radiation Effects on the Ultrastructure of Rat Cerebellar Cortex / 대한해부학회지

Severe irradiation on head may result functional alterations of central nervous system. In this study, the irradiation effect on the cerebellar cortex following heavy X-irradiation on head was studied ultrastructurally. Radiation was produced with the linear accelerator ML-4MV[Mitshubishi Co.], and rats weighing about 200gm each were exposed their heads within the radiation areas of 30cm x 30cm, under the radiation distance of 80cm, and with the radiation depth of 1.2 cm. Radiation doses were 3,000rads or 6,000rads, respectively. Animals were sacrificed on 6 hours, 2 days or 6 days following the radiation. Under anesthesia, animals were perfused with 1% glutaraldehyde-1% paraformaldehyde solution. Two hours after the perfusion, brain were taken out and refixed over night in the perfusion fixative. Small blocks of cerebellar hemispheric cortices were refixed 2 hours in 2% osmium tetroxide solution. Fixed tissues were dehydrated in alcohol, embedded in araldite mixture, and cut with ultratome. Ultrathin sections were contrasted with uranyl acetate and lead citrate solutions, and observed with electron microscope. The results obstained were as follow : 1. On 6th hour following X-irradiations, many cerebellar cortical neurons showed increased electron densities, more complicated nuclear infoldings, depletion of synaptic vesicles, expansion of astroglial territories, etc. 2. On 2nd day following X-irradiations, many organelle-rich cells such as Purkinje cells and Golgi cells were darkly degenerated. Numerous myelin figures formed by the cisternal fusions of Golgi apparatus or granular endoplasmic reticula were observed. Cytoplasmic processes of activated astroglial cells were expanded around capillaries and between granule cells. 3. On 6th day following X-irradiations, morphology of neuropil and neurones in the cerebellar cortex was generally restored, except the expanded territories of astroglial cells. From the above results, it was concluded that the release ofneurotransmitters and transcapillary leakage of blood substance were occurred on 6 hours after heavy X-irradiations. And severe alterations were produced on 2 day after X-irradiation, but the condition was generally restored on 6th day following X-irradiation.