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Molecular and cellular characterization of the age‐related neuroinflammatory processes occurring in normal rat hippocampus: potential relation with the loss of somatostatin GABAergic neurons
Author(s) -
Gavilán M. Paz,
Revilla Elisa,
Pintado Cristina,
Castaño Angélica,
Vizuete M. Luisa,
MorenoGonzález Inés,
BagliettoVargas David,
SánchezVaro Raquel,
Vitorica Javier,
Gutiérrez Antonia,
Ruano Diego
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04787.x
Subject(s) - somatostatin , hippocampal formation , dentate gyrus , neuroinflammation , hippocampus , endocrinology , gabaergic , medicine , neurodegeneration , biology , parvalbumin , neuropeptide , neuroscience , inflammation , inhibitory postsynaptic potential , receptor , disease
Increased neuroinflammatory reaction is frequently observed during normal brain aging. However, a direct link between neuroinflammation and neurodegeneration during aging has not yet been clearly shown. Here, we have characterized the age‐related hippocampal inflammatory processes and the potential relation with hippocampal neurodegeneration. The mRNA expression of the pro‐inflammatory cytokines IL‐1β and tumor necrosis factor‐α (TNF‐α), and the iNOs enzyme was significantly increased in aged hippocampus. Accordingly, numerous activated microglial cells were observed in aged rats. These cells were differentially distributed along the hippocampus, being more frequently located in the hilus and the CA3 area. The mRNA expression of somatostatin, a neuropeptide expressed by some GABAergic interneurons, and the number of somatostatin‐immunopositive cells decreased in aged rats. However, the number of hippocampal parvalbumin‐containing GABAergic interneurons was preserved. Interestingly, in aged rats, the mRNA expression of somatostatin and IL‐1β was inversely correlated and, the decrease in the number of somatostatin‐immunopositive cells was higher in the hilus of dentate gyrus than in the CA1 region. Finally, intraperitoneal chronic lipopolysaccharide (LPS) injection in young animals mimicked the age‐related hippocampal inflammation as well as the decrease of somatostatin mRNA expression. Present results strongly support the neuroinflammation as a potential factor involved in the age‐related degeneration of somatostatin GABAergic cells.