title: Effects of oxygen and glucose deprivation on synaptic transmission in rat dentate gyrus: role of A2A adenosine receptors.
abstract: The hippocampus is comprised of two distinct subfields that show different responses to hypoxic-ischemic brain injury: the CA1 region is particularly susceptible whereas the dentate gyrus (DG) is quite resistant. Our aim was to determine the synaptic and proliferative response of the DG to severe oxygen and glucose deprivation (OGD) in acute rat hippocampal slices and to investigate the contribution of A(2A) adenosine receptor antagonism to recovery of synaptic activity after OGD. Extracellular recordings of field excitatory post-synaptic potentials (fEPSPs) in granule cells of the DG in brain slices prepared from male Wistar rats were used. A 9-min OGD is needed in the DG to always induce the appearance of anoxic depolarization (AD) and the irreversible block of synaptic activity, as recorded up to 24 h from the end of the insult, whereas only 7-min OGD is required in the CA1 region. Selective antagonism of A(2A) adenosine receptors by ZM241385 significantly prevents or delays the appearance of AD and protects from the irreversible block of neurotransmission induced by 9-min OGD in the DG. The effects of 9-min OGD on proliferation and maturation of cells localized in the subgranular zone of DG in slices prepared from 5-bromo-2'-deoxyuridine (BrdU) treated rats was investigated. Slices were further incubated with an immature neuronal marker, doublecortin (DCX). The number of BrdU(+) cells was significantly decreased 6 h after 9-min OGD and this effect was antagonized by ZM241385. After 24 h from the end of 9-min OGD, the number of BrdU(+) cells returned to that found before OGD and increased arborization of tertiary dendrites of DCX(+) cells was observed. The adenosine A(2A) antagonist ZM241385 protects from synaptic failure and from decreased proliferation of immature neuronal cells at a precocious time after OGD.
authors.affiliation: Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Maraula
authors.forename: Chiara
authors.initials: C
authors.lastname: Traini
authors.forename: Tommaso
authors.initials: T
authors.lastname: Mello
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Coppi
authors.forename: Andrea
authors.initials: A
authors.lastname: Galli
authors.forename: Felicita
authors.initials: F
authors.lastname: Pedata
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Pugliese
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism*; D000089662:Doublecortin Protein; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005947:Glucose / Q000172:deficiency*; D008297:Male; D009924:Organ Culture Techniques; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D043705:Receptor, Adenosine A2A / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D014227:Triazines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
chemical_list: C000714848:Dcx protein, rat; D000089662:Doublecortin Protein; D043705:Receptor, Adenosine A2A; D014227:Triazines; D014230:Triazoles; C097270:ZM 241385; D005947:Glucose; D010100:Oxygen