A Possible Role of the Non-GAT1 GABA Transporters in Transfer of GABA From GABAergic to Glutamatergic Neurons in Mouse Cerebellar Neuronal Cultures |
| |
Authors: | C Suñol Z Babot R Cristòfol U Sonnewald H S Waagepetersen A Schousboe |
| |
Institution: | 1.Department of Neurochemistry and Neuropharmacology, Institut d’Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, CSIC-IDIBAPS,CIBERESP,Barcelona,Spain;2.Department of Neuroscience, Faculty of Medicine, MTFS,NTNU,Trondheim,Norway;3.Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences,University of Copenhagen,Copenhagen,Denmark |
| |
Abstract: | Cultures of dissociated cerebellum from 7-day-old mice were used to investigate the mechanism involved in synthesis and cellular
redistribution of GABA in these cultures consisting primarily of glutamatergic granule neurons and a smaller population of
GABAergic Golgi and stellate neurons. The distribution of GAD, GABA and the vesicular glutamate transporter VGlut-1 was assessed
using specific antibodies combined with immunofluorescence microscopy. Additionally, tiagabine, SKF 89976-A, betaine, β-alanine,
nipecotic acid and guvacine were used to inhibit the GAT1, betaine/GABA (BGT1), GAT2 and GAT3 transporters. Only a small population
of cells were immuno-stained for GAD while many cells exhibited VGlut-1 like immuno-reactivity which, however, never co-localized
with GAD positive neurons. This likely reflects the small number of GABAergic neurons compared to the glutamatergic granule
neurons constituting the majority of the cells. GABA uptake exhibited the kinetics of high affinity transport and could be
partly (20%) inhibited by betaine (IC50 142 μM), β-alanine (30%) and almost fully (90%) inhibited by SKF 89976-A (IC50 0.8 μM) or nipecotic acid and guvacine at 1 mM concentrations (95%). Essentially all neurons showed GABA like immunostaining
albeit with differences in intensity. The results indicate that GABA which is synthesized in a small population of GAD-positive
neurons is redistributed to essentially all neurons including the glutamatergic granule cells. GAT1 is not likely involved
in this redistribution since addition of 15 μM tiagabine (GAT1 inhibitor) to the culture medium had no effect on the overall
GABA content of the cells. Likewise the BGT1 transporter cannot alone account for the redistribution since inclusion of 3 mM
betaine in the culture medium had no effect on the overall GABA content. The inhibitory action of β-alanine and high concentrations
of nipecotic acid and guvacine on GABA transport strongly suggests that also GAT2 or GAT3 (HUGO nomenclature) could play a
role. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|