KCC2 is hypothesized to serve as the Cl- extrusion mechanism, maintaining internal Cl- below electrochemical equilibrium as required for proper GABAA receptor inhibitory function. In early postnatal (PN) development, however, GABAA receptors are mainly excitatory, but switch to inhibitory during week 2 of PN development. This change in GABAA receptor function appears to result from the slow development of a Cl-1 extrusion mechanism, using recently developed anti-KCC2 polyclonal antibodies, we examined the temporal expression of KCC2 in PN development to test its correlation with the appearance of a neuronal Cl- extrusion mechanism. Western blot analysis of whole rat brain membranes showed little protein at PN day 4. KCC2 protein became evident at day 10 and increased steadily until adult levels were attained at day 28. In immunolocalization studies, a peroxidase method was use to detect KCC2 in saggital brain sections. No positive staining for KCC2 was seen at day 4. At day 10, positive staining in the cerebellum was seen mainly in the molecular cell layer. In the hippocampus, light staining for KCC2 was seen in the apical dendrites of CA1-CA3 pyramidal neurons and dentate gyrus granule cells. The neocortex showed light punctate perisomal staining with little dendritic staining evident. Day 14 showed more intense KCC2 staining in the same regions identified at day 10, and the cerebellar granule cell layer showed the beginnings of punctate staining found in the adult brain. The results are consistent with the important role of KCC2 in neuronal Cl- extrusion and the functional development of GABAA receptors.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology