title: Expression of gap junction protein connexin36 in multiple subtypes of GABAergic neurons in adult rat somatosensory cortex.
abstract: To characterize connexin36 (Cx36)-expressing neurons of the adult rat somatosensory cortex, we examined fluorescence signals for Cx36 messenger RNA (mRNA) in 3 nonoverlapping subpopulations of γ-aminobutyric acid (GABA)ergic interneurons, which showed immunoreactivity for 1) parvalbumin (PV); 2) somatostatin (SOM); and 3) either calretinin (CR), vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), or choline acetyltransferase (ChAT). About 80% of PV-, 52% of SOM-, 37% of CR/VIP/CCK/ChAT-immunoreactive cells displayed Cx36 signals across all cortical layers, and inversely 64%, 25%, and 9% of Cx36-expressing neurons were positive for PV, SOM, or CR/VIP/CCK/ChAT, respectively. Notably, although almost all Cx36-expressing neurons in layer (L) 4, L5, and L6 were positive for one of these markers, a substantial proportion of those in L1 (91%) and L2/3 (10%) were negative for the markers tested, suggesting that other types of neurons might express Cx36. We further investigated the colocalization of Cx36 mRNA and α-actinin2 immunoreactivity, as a marker for late-spiking GABAergic neurons, by using mirror-image sections. Surprisingly, more than 77% of α-actinin2-positive cells displayed Cx36 signals in L1-L3, and about 49% and 13% of Cx36-expressing neurons were positive for α-actinin2 in L1 and L2/3, respectively. These findings suggest that all the subtypes of GABAergic interneurons might form gap junctions in the neocortex.
authors.affiliation: Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Ma
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hioki
authors.forename: Michiteru
authors.initials: M
authors.lastname: Konno
authors.forename: Shixiu
authors.initials: S
authors.lastname: Pan
authors.forename: Hisashi
authors.initials: H
authors.lastname: Nakamura
authors.forename: Kouichi C
authors.initials: KC
authors.lastname: Nakamura
authors.forename: Takahiro
authors.initials: T
authors.lastname: Furuta
authors.forename: Jin-Lian
authors.initials: JL
authors.lastname: Li
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kaneko
mesh_terms: D000818:Animals; D017630:Connexins / Q000096:biosynthesis*; D059330:GABAergic Neurons / Q000378:metabolism*; D017629:Gap Junctions / Q000378:metabolism; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000378:metabolism*; D000097004:Gap Junction delta-2 Protein
chemical_list: D017630:Connexins; D000097004:Gap Junction delta-2 Protein