title: Stress by noise produces differential effects on the proliferation rate of radial astrocytes and survival of neuroblasts in the adult subgranular zone.
abstract: The subgranular zone (SGZ) in the dentate gyrus contains radial astrocytes, known as Type-1 or Type-B cells, which generate neuroblasts (Type-2 cells or Type-D cells) that give rise to granular neurons. Stress increases glucocorticoid levels that target SGZ and modify the proliferation and apoptosis of hippocampal cells. Yet, it is not well-known whether stress differentially affects SGZ progenitors. We investigated the effects of noise-induced stress on the rate of proliferation and apoptosis of the Type-1 cells, Type-2 cells and newly generated granular neurons in the SGZ. We exposed Balb/C mice to noise using a standardized rodents' audiogram-fitted adaptation of a human noisy environment. We measured corticosterone serum levels at different time points. Animals received BrdU injections for 3 days and sequential sacrifices were done to carry out double-immunohistochemical analyses. We found that a 24-h noise exposure did not produce adaptative response in the curve of corticosterone as compared to a 12-h noise exposure. The percentage of BrdU+/GFAP+ cells was significantly reduced in the stress group as compared to controls. A high proportion of CASP-3+/GFAP+ radial astrocytes were found in the stress group. The percentage of BrdU+/doublecortin+ cells was higher in controls than in the stress group. Interestingly, the apoptosis rate of doublecortin-expressing cells in the stress group was slightly lesser than in controls. Remarkably, we did not find significant differences in the number of BrdU+/NeuN+ and CASP-3+/NeuN+ neurons. These data indicate that stress differentially affects the rate of proliferation and apoptosis in SGZ progenitors and suggest a possible compensatory mechanism to keep the net number of granular neurons.
authors.affiliation: Laboratory of Neuroscience, Facultad de Psicologia, University of Colima, Colima 28040, Mexico. osglez@gmail.com
authors.forename: Oscar
authors.initials: O
authors.lastname: Gonzalez-Perez
authors.forename: Oscar
authors.initials: O
authors.lastname: Chavez-Casillas
authors.forename: Fernando
authors.initials: F
authors.lastname: Jauregui-Huerta
authors.forename: Veronica
authors.initials: V
authors.lastname: Lopez-Virgen
authors.forename: Jorge
authors.initials: J
authors.lastname: Guzman-Muniz
authors.forename: Norma
authors.initials: N
authors.lastname: Moy-Lopez
authors.forename: Rocio E
authors.initials: RE
authors.lastname: Gonzalez-Castaneda
authors.forename: Sonia
authors.initials: S
authors.lastname: Luquin
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000502:physiology*; D018891:Dentate Gyrus / Q000166:cytology / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D058953:Neural Stem Cells / Q000166:cytology / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology*; D009622:Noise / Q000009:adverse effects*; D013312:Stress, Physiological / Q000502:physiology*