Morphological changes in hippocampal astrocytes induced by environmental enrichment in mice

Abstract

Environmental enrichment is known to induce plastic changes in the brain, including morphological changes in hippocampal neurons, with increases in synaptic and spine densities. In recent years, the evidence for a role of astrocytes in regulating synaptic transmission and plasticity has increased, and it is likely that morphological and functional changes in astrocytes play an important role in brain plasticity. Our study was designed to evaluate changes in astrocytes induced by environmental enrichment in the CA1 region of the hippocampus, focusing on astrocytic density and on morphological changes in astrocytic processes. After 8 weeks of environmental enrichment starting at weaning, male CF-1 mice presented no significant changes in astrocyte number or in the density of glial fibrillary acidic protein (GFAP) immunoreactivity in the stratum radiatum. However, they did present changes in astrocytic morphology in the same region, as expressed by a significant increase in the ramification of astrocytic processes measured by the Sholl concentric circles method, as well as by an increase in the number and length of primary processes extending in a parallel orientation to CA1 nerve fibers. This led astrocytes to acquire a more stellate morphology, a fact which could be related to the increase in hippocampal synaptic density observed in previous studies. These findings corroborate the idea that structural changes in astrocytic networks are an integral part of plasticity processes occurring in the brain.

Hippocampal astrocytes are necessary for antidepressant treatment of learned helplessness rats

“…Thus, the LH paradigm induced increases in the number of activated and nonactivated astrocytes, which could be a compensatory response to stress. In support of this, environmental enrichment, which increases neurogenesis in the hippocampus, produced an increase in the ramification of astrocytic processes and the number and length of primary processes extending in the hippocampus (Viola et al, 2009). Furthermore, an increase in the number of GFAP-labeled astrocytes was seen in the cingulate of postpartum rats (Salmaso et al, 2009).…”

“…3). Reactive astrocytes are recognized by GFAP labeling and extended lengths of processes (Viola et al, 2009). We differentiated activated astrocytes from nonactivated astrocytes mainly by dimension rather than by length of longest process.…”

NADPH-diaphorase activity in the nociceptive pathways of land snail Megalobulimus abbreviatus: the involvement of pedal ganglia

“…Regional densitometry is a measurement of absorbance generated by the NADPH-d reaction product, formazan, in all the tissues, including neurons, glia and fibers, while neuronal optical densitometry is the same measurement performed only in the neuronal cytoplasm Xavier et al 2005;Vaschenko and Kotsyuba 2008;Viola et al 2009). For this purpose, a Nikon-Eclipse E-600 microscope (500x; Japan) was employed together with Image Pro-Plus Software 6.0 (Media Cybernetics, USA).…”

“…The NADPH-d activity was evaluated using regional and neuronal semi-quantitative optical densitometry Xavier et al 2005;Vaschenko and Kotsyuba 2008;Viola et al 2009). Regional densitometry is a measurement of absorbance generated by the NADPH-d reaction product, formazan, in all the tissues, including neurons, glia and fibers, while neuronal optical densitometry is the same measurement performed only in the neuronal cytoplasm Xavier et al 2005;Vaschenko and Kotsyuba 2008;Viola et al 2009).…”

Strain Differences and Effects of Environmental Manipulation on Astrocytes (Glial Fibrillary Acidic Protein), Glucocorticoid Receptor, and Microglia (Iba1) Immunoreactivity between Wistar-Kyoto and Wistar Females

“…In this study, female Wistar rats in the EE condition showed significantly higher staining intensity and percent area of staining for astroglia in the CA1, but not CA3. While another study of male mice [43] found no change in immunoreactivity or density of astroglia following EE, it did report structural changes in the hippocampal CA1 following EE. In the motor cortex of adult female mice, EE has been shown to increase the number of astroglia [44].…”