Entorhinal cortex lesion or intrahippocampal colchicine injection increases peripheral type benzodiazepine binding sites in rat hippocampus.
The peripheral type benzodiazepine binding site (PTBBS) has been proposed to be a good marker for reactive glial cells following brain insults. In the present study, homogenate binding of 3H-Ro5-4864 and quantitative autoradiography of 3H-PK-11195 binding (two ligands for the PTBBS) were used to assess the distribution, time-course and extent of reactive gliosis in the hippocampus following deafferentation by unilateral entorhinal cortex lesion or neuronal death produced by intrahippocampal colchicine injection. Intrahippocampal colchicine injections produced a 3-fold increase in 3H-Ro5-4864 binding in the dentate gyrus within 2 days. This effect was doubled in animals pretreated with the lysosomal inhibitor chloroquine. Quantitative autoradiography of 3H-PK-11195 binding 1 or 2 weeks after colchicine injection indicated that the increase in binding was restricted to the dorsal hippocampus both rostrally and caudally and was present in the dentate gyrus and CA1. Following a unilateral electrolytic lesion of the entorhinal cortex, the binding of 3H-Ro5-4864 to homogenates of the dentate gyrus was doubled 18 h after the lesion, reached a maximum at 4 days post-lesion, and returned to control values by 2 months after the lesion. A transient increase in binding was also observed 2 and 4 days post-lesion in the dentate gyrus contralateral to the lesion side. Autoradiography of 3H-PK-11195 binding indicated that the increase in PTBBS following entorhinal cortex lesion was restricted to the molecular layer of the dentate gyrus.(ABSTRACT TRUNCATED AT 250 WORDS)
Baudry
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Program in Neural, Informational, and Behavioral Sciences, University of Southern California, Los Angeles 90089-2520.
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D000818:Animals; D001345:Autoradiography; D001570:Benzodiazepinones / Q000378:metabolism; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D002738:Chloroquine / Q000008:administration & dosage / Q000494:pharmacology*; D003078:Colchicine / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D007276:Injections, Intraventricular; D007546:Isoquinolines / Q000378:metabolism; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
D001570:Benzodiazepinones; D007546:Isoquinolines; D011963:Receptors, GABA-A; D014316:Tritium; C028513:4'-chlorodiazepam; D002738:Chloroquine; D003078:Colchicine; C037850:PK 11195