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Differential expression of γ‐aminobutyric acid‐A receptor subunits in rat dorsal and ventral hippocampus
Author(s) -
Sotiriou Evangelos,
Papatheodoropoulos Costas,
Angelatou Fevronia
Publication year - 2005
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.20670
Subject(s) - muscimol , gabaa receptor , receptor , agonist , protein subunit , medicine , endocrinology , dentate gyrus , chemistry , biology , hippocampus , microbiology and biotechnology , biochemistry , gene
Recent data demonstrate weaker γ‐aminobutyric acid (GABA)‐ergic inhibition in ventral (VH) compared with dorsal (DH) hippocampus. Therefore, we examined possible differences regarding the GABA A receptors between VH and DH as follows: 1) the expression of the GABA A receptor subunits (α1/2/4/5, β1/2/3, γ2, δ) mRNA and protein and 2) the quantitative distribution and kinetic parameters of [ 3 H]muscimol (GABA A receptor agonist) binding. VH compared with DH showed: 1) lower levels for α1, β2, γ2 but higher levels for α2 and β1 subunits in CA1, CA2, and CA3, the differences being more pronounced in CA1 region; in the CA1 region, the mRNA levels of α5 were higher, whereas those of α4 subunit were slightly lower; in dentate gyrus, the mRNA levels of α4, β3, and δ subunits were significantly lower, presumably suggesting a lower expression of the α4/β3/δ receptor subtype; and 2) lower levels of [ 3 H]muscimol binding, with the lowest value observed in CA1, apparently resulting from weaker binding affinity, insofar as the K D values were higher in VH, whereas the B max values were similar between DH and VH. The differences in the subunit expression and the lower affinity of GABA A receptor binding observed predominantly in the CA1 region of VH suggest that the α1/β2/γ2 GABA A receptor subtype dominates in DH, and the α2/β1/γ2 subtype prevails in VH. This could underlie the lower GABA A ‐mediated inhibition observed in VH and, to some extent, explain 1) the higher liability of VH for epileptic activity and 2) the differential involvement of DH and VH in cognitive and emotional processes. © 2005 Wiley‐Liss, Inc.