Implication of non-NMDA and NMDA receptors in cochlear ischemia.
We have investigated the hypothesis that the acute ischemic swelling of the radial dendrites connected to the inner hair cells (IHCs) is mediated by glutamatergic receptors. In control cochleas, after 20 min ischemia all the dendrites were dramatically swollen. Conversely, after a perfusion of 50 microM 6-7-dinitroquinoxaline-2,3-dione (DNQX) before ischemia, most dendrites were protected although those contacting the IHCs on their modiolar side frequently swelled. After 50 microM of D-2-amino-5-phosphonopentanoate (D-AP5), no dendrite protection could be obtained. Finally, after DNQX and D-AP5, no dendrite swelling occurred. These results suggest that, in the cochlea, the acute ischemic swelling of dendrites primarily occurs via non-NMDA receptors. However, in radial dendrites contacting the IHCs on their modiolar side, NMDA receptors may contribute to excitotoxicity.
INSERM U.254, Laboratoire de Neurobiologie de l'Audition, Hôpital St. Charles, Montpellier, France.
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Pujol
J L
JL
Puel
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Eybalin
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D003051:Cochlea / Q000098:blood supply* / Q000648:ultrastructure; D003712:Dendrites / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000503:physiopathology* / Q000648:ultrastructure; D007511:Ischemia / Q000473:pathology / Q000503:physiopathology*; D008854:Microscopy, Electron; D011810:Quinoxalines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D015424:Reperfusion
D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; C056723:FG 9041; D015763:2-Amino-5-phosphonovalerate