title: Age-dependent enhancement of inhibitory synaptic transmission in CA1 pyramidal neurons via GluR5 kainate receptors.
abstract: Changes in hippocampal synaptic networks during aging may contribute to age-dependent compromise of cognitive functions such as learning and memory. Previous studies have demonstrated that GABAergic synaptic transmission exhibits age-dependent changes. To better understand such age-dependent changes of GABAergic synaptic inhibition, we performed whole-cell recordings from pyramidal cells in the CA1 area of acute hippocampal slices on aged (24-26 months old) and young (2-4 months old) Brown-Norway rats. We found that the frequency and amplitude of spontaneous inhibitory postsynaptic current (IPSCs) were significantly increased in aged rats, but the frequency and amplitude of mIPSCs were decreased. Furthermore, the regulation of GABAergic synaptic transmission by GluR5 containing kainate receptors was enhanced in aged rats, which was revealed by using LY382884 (a GluR5 kainate receptor antagonist) and ATPA (a GluR5 kainate receptor agonist). Moreover, we demonstrated that vesicular glutamate transporters are involved in the kainate receptor dependent regulation of sIPSCs. Taken together, these results suggest that GABAergic synaptic transmission is potentiated in aged rats, and GluR5 containing kainate receptors regulate the inhibitory synaptic transmission through endogenous glutamate. These alterations of GABAergic input with aging could contribute to age-dependent cognitive decline.
authors.affiliation: Blanchette Rockefeller Neurosciences Institute, Rockville, Maryland 20850-3332, USA. changqing@brni-jhu.org
authors.forename: Changqing
authors.initials: C
authors.lastname: Xu
authors.forename: Changhai
authors.initials: C
authors.lastname: Cui
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Alkon
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects; D008297:Male; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology; D017966:Pyramidal Cells / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism; D018092:Kainic Acid Receptors / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors; D050496:Vesicular Glutamate Transport Proteins / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D018698:Glutamic Acid; D018091:Receptors, AMPA; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D050496:Vesicular Glutamate Transport Proteins; D005680:gamma-Aminobutyric Acid