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Cellular expression of connexins in the rat brain: neuronal localization, effects of kainate‐induced seizures and expression in apoptotic neuronal cells
Author(s) -
Condorelli Daniele F.,
TrovatoSalinaro Angela,
Mudò Giuseppa,
Mirone Melita B.,
Belluardo Natale
Publication year - 2003
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2003.02910.x
Subject(s) - biology , connexin , hippocampus , in situ hybridization , neuroscience , neuron , kainate receptor , apoptosis , immunohistochemistry , gap junction , programmed cell death , premovement neuronal activity , microbiology and biotechnology , messenger rna , gene , immunology , receptor , glutamate receptor , genetics , intracellular , ampa receptor
The identification of connexins (Cxs) expressed in neuronal cells represents a crucial step for understanding the direct communication between neurons and between neuron and glia. In the present work, using a double‐labelling method combining in situ hybridization for Cx mRNAs with immunohistochemical detection for neuronal markers, we provide evidence that, among cerebral connexins (Cx26, Cx32, Cx36, Cx37, Cx40, Cx43, Cx45 and Cx47), only Cx45 and Cx36 mRNAs are localized in neuronal cells in both developing and adult rat brain. In order to establish whether connexin expression is influenced in vivo by abnormal neuronal activity, we examined the short‐term effects of kainate‐induced seizures. The results revealed an unexpected expression of Cx26 and Cx45 mRNA in neuronal cells undergoing apoptotic cell death in the CA3–CA4, in the hilus of the hippocampus and in other brain regions involved in seizure‐induced lesion. However, the expression of Cx26 and Cx45 mRNAs was not associated with detectable expression of corresponding proteins as evaluated by immunohistochemistry with specific antibodies. Moreover, in the same brain regions Cx32 and Cx43 were up‐regulated in non‐neruronal cells whereas the neuronal Cx36 was down‐regulated. Taken together the present results provide novel information regarding the specific subpopulation of neurons expressing Cx45 and raise the question of the meaning of connexin mRNA expression in the neuronal apoptotic process.