Poster
# 25
Poster |
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6th Internet World Congress for Biomedical Sciences |
María Jesús Ramírez-Expósito(1), José Manuel Martínez-Martos(2)
(1)Unit of Physiology. University of Jaen - Jaén. Spain
(2)Unit of Physiology. University of Jaén - Jaén. Spain
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[Cell Biology & Cytology] |
[Neuroscience] |
[Physiology] |
In the present work, the quantitative study has been made using micrometer-ocular techniques. These methods have been clasically the most used (O´kusky and Colonnier, 1982; Konigsmark, 1970, Trillo y Gonzalez, 1992) because it sis possible to count directly the number of cells into a grid. However, in the last years, authomatic methods (quicker and less hard) are been developed (Antal et al., 1992; Coggeshall, 1992), but these techniques diferenciate the cell population by their size, so in our study, we can not deifferenciate the glial cells because their size is very similar. Recently, the used of inmunocytochemical techniques has been also questioned because crossed stained may happen.
In this work we have chosen optical microscope techniques based on morphological criteria (O´kusky and colonnier, 1982; Sturrock, 1983; Peter et al., 1991). Frontal cortex have been chose because this area is the target of some projections and its alterations may be responsible of some cognitive disfunction (Kemper,1984; Amenta et al., 1992; 1994).
The reactivity of glial cells in the CNS during aging and different pathologies as ischemic, trauma or degenerative disorders is well known (Hajos et al., 1990; Landis, 1994; Myers et al., 1993; Giulian and Vaca, 1993; Kempsky and Volk, 1994; Ridoux et al., 1994; Leuba and Kraftsik, 1994a, Mieto Sanpedro y Mora, 1994; Streit, 1996). Some authors have suggested that quantitative changes observed in glial cells during these situation may be related with the changes in number of neurons and also with metabolic variations (Sturrock, 1983). The methods used in this study allowed us to differenciated the different glial cell types and so, it si possible to know which glial type participate in gliosis process.
Quantitative studies of glial population during aging are heterogenous and also contradictory. A first group of authors do not find quantitative changes with aging in glial cells (Curcio and Coleman, 1982; Haug et al., 1984). In other studies, the results are different depending to the studied area (Haug et al., 1983), the method used (Cragg, 1975; Sturrock, 1983, Haug et al., 1984; Vincent et al., 1989) and the animal model (Curcio and Coleman, 1982).
Our results showed an increase in the total glial cells during aging in the studied area. The most affected cortical layer is layer V.
Astrocytes are considered as the most affected cells during aging, and significant increases have been described in white matter of mice (Bronson et al., 1993) and in frontal cortex of old rats (Amenta et al., 1994). Simillar variations have been observed in the hippocampus (Landfield et al., 1977; Lolova,1991). Our results are in acccordance with that studies because we found age-related increases in astrocytes.
In present work, the microglial cells and oligodendrocytes were quantified together because these glial cell types are not distinguish by morphological and stained criteria (Vaughan, 1989; Peter et al., 1994). Our results did not show changes with aged, except in cortical layer I. These dates are in accordance with the study of lawson and col (1992). However, althoug no quantitative changes were observed, an increased in the reactivity of microglial cells has been described (ogura et al., 1994; Perry et al., 1993). The presence of reactive microglia during ageing may be related with the neurodegenerative process happened during aging and may be implicated in control of synapsis (Adams and Jones, 1982) and with the remodelation of dendrites (Flood and Coleman, 1981). By contrast other authors have described light increase in microglial cells with aging (Vaughan and Peter, 1974; Peter et al., 1991; 1994).
The effects of induced and cronical lesions in the frontal cortex also have been studied. It is known that cerebral injuries in adult animals produce degeneration (Jones and Cowan, 1983). However, our results are difficult to dicuss because is a specific lesion.
an increase in glial cell number was observed with aging and lesions, because independly, these procceses cause reactive gliosis (Sturrock, 1983; Haug et al., 1984; Landis, 1994; Giordana et al., 1993). The combined effects of aged and lesions showed a high glial reaction. However, the glial cell type implicated in ageing and lesions is different. Aging induced an increase in astrocytes, but lesions, analized in contralateral side, produced an increase in microglia-oligodendrocytes, but astrocytes did not change. It could be possible due to a compensatory effects to the increase produce in ageing ant to the possible decrease during lesions.
Other important results are the different behaviour of cortical layers. Aging only produces changes in cortical layer V, but the combinatory effects of lesions and aging affected to all the thicknes of cortex. Theses results suggest that the effects of lesion are over the aging.
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[Cell Biology & Cytology] |
[Neuroscience] |
[Physiology] |
