Ultrastructure of parvalbumin-immunoreactive neurons in the CA1 area of the rat hippocampus following a kainic acid injection.
Non-pyramidal neurons which contain the calcium-binding protein parvalbumin (PV) were examined, at the ultrastructural level, in the CA1 area of the normal hippocampus and following a unilateral intracerebroventricular kainic acid (KA) injection. Many degenerating PV-immunoreactive (IR) neurons were identified in the ipsilateral strata oriens and pyramidale at 3 days post-lesion and some were seen in stratum oriens of the contralateral CA1 area. A few PV-IR neurons remained resistant to the effects of KA. A chronic, almost total loss of PV-IR terminals was detected around the soma of the ipsilateral CA1 pyramidal neurons. However, the PV-IR terminals around the axon initial segments of the CA1 pyramidial neurons remained intact at all post-lesion survival times in both ipsilateral and contralateral tissue. The examination of serial ultrathin sections established the origin of the PV-IR terminals around the axon initial segments to be the KA-resistant PV-IR neurons in stratum pyramidale. This data provides evidence for the loss of non-pyramidal neurons following a KA lesion together with evidence for a surviving inhibitory circuit that could, if functional, provide a very strong inhibitory control of pyramidal neurons.
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Department of Human Morphology, University of Southampton, UK.
Mitchell
J
J
Wheal
H V
HV
D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006624:Hippocampus / Q000187:drug effects / Q000648:ultrastructure*; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000648:ultrastructure*; D010320:Parvalbumins / Q000276:immunology / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D016707:Tissue Fixation
D010320:Parvalbumins; D007608:Kainic Acid