Tags

Type your tag names separated by a space and hit enter

Astrocytic processes compensate for the apparent lack of GABA transporters in the axon terminals of cerebellar Purkinje cells.
Anat Embryol (Berl) 1996; 194(4):379-90AE

Abstract

The aim of the present study was to evaluate the expression of two high affinity GABA transporters (GAT-1 and GAT-3) in the rat cerebellum using immunocytochemistry and affinity purified antibodies. GAT-1 immunoreactivity was prominent in punctate structures and axons in all layers of the cerebellar cortex, and was especially prominent around the somata of Purkinje cells. In contrast, the deep cerebellar nuclei showed few if any GAT-1 immunoreactive puncta. Weak GAT-3 immunoreactive processes were present in the cerebellar cortex, whereas GAT-3 immunostaining was prominent around the somata of neurons in the deep cerebellar nuclei. Electron microscopic preparations of the cerebellar cortex demonstrated that GAT-1 immunoreactive axon terminals formed symmetric synapses with somata, axon initial segments and dendrites of Purkinje cells and the dendrites of granule cells. Astrocytic processes in the cerebellar cortex were also immunolabeled for GAT-1. However, Purkinje cell axon terminals that formed symmetric synapses with neurons in the deep cerebellar nuclei lacked GAT-1 immunoreactivity. Instead, weak GAT-1 and strong GAT-3 immunoreactivities were expressed by astrocytic processes that enveloped the Purkinje cell axon terminals. In addition, GAT-3-immunoreactivity appeared in astrocytic processes in the cerebellar cortex. These observations demonstrate that GAT-1 is localized to axon terminals of three of the four neuronal types that were previously established as being GABAergic, i.e. basket, stellate and Golgi cells. GAT-1 and GAT-3 are expressed by astrocytes. The failure to identify a GABA transporter in Purkinje cells is consistent with previous data that indicated that Purkinje cells lacked terminal uptake mechanisms for GABA. The individual glial envelopment of Purkinje cell axon terminals in the deep cerebellar nuclei and the dense immunostaining of GAT-3, and to a lesser extent GAT-1, expressed by astrocytic processes provide a compensatory mechanism for the removal of GABA from the synaptic cleft of synapses formed by Purkinje cell axon terminals.

Authors+Show Affiliations

Department of Anatomy and Neurobiology, University of California, Irvine 92717, USA. ceribak@uci.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8896702

Citation

Ribak, C E., et al. "Astrocytic Processes Compensate for the Apparent Lack of GABA Transporters in the Axon Terminals of Cerebellar Purkinje Cells." Anatomy and Embryology, vol. 194, no. 4, 1996, pp. 379-90.
Ribak CE, Tong WM, Brecha NC. Astrocytic processes compensate for the apparent lack of GABA transporters in the axon terminals of cerebellar Purkinje cells. Anat Embryol. 1996;194(4):379-90.
Ribak, C. E., Tong, W. M., & Brecha, N. C. (1996). Astrocytic processes compensate for the apparent lack of GABA transporters in the axon terminals of cerebellar Purkinje cells. Anatomy and Embryology, 194(4), pp. 379-90.
Ribak CE, Tong WM, Brecha NC. Astrocytic Processes Compensate for the Apparent Lack of GABA Transporters in the Axon Terminals of Cerebellar Purkinje Cells. Anat Embryol. 1996;194(4):379-90. PubMed PMID: 8896702.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Astrocytic processes compensate for the apparent lack of GABA transporters in the axon terminals of cerebellar Purkinje cells. AU - Ribak,C E, AU - Tong,W M, AU - Brecha,N C, PY - 1996/10/1/pubmed PY - 1996/10/1/medline PY - 1996/10/1/entrez SP - 379 EP - 90 JF - Anatomy and embryology JO - Anat. Embryol. VL - 194 IS - 4 N2 - The aim of the present study was to evaluate the expression of two high affinity GABA transporters (GAT-1 and GAT-3) in the rat cerebellum using immunocytochemistry and affinity purified antibodies. GAT-1 immunoreactivity was prominent in punctate structures and axons in all layers of the cerebellar cortex, and was especially prominent around the somata of Purkinje cells. In contrast, the deep cerebellar nuclei showed few if any GAT-1 immunoreactive puncta. Weak GAT-3 immunoreactive processes were present in the cerebellar cortex, whereas GAT-3 immunostaining was prominent around the somata of neurons in the deep cerebellar nuclei. Electron microscopic preparations of the cerebellar cortex demonstrated that GAT-1 immunoreactive axon terminals formed symmetric synapses with somata, axon initial segments and dendrites of Purkinje cells and the dendrites of granule cells. Astrocytic processes in the cerebellar cortex were also immunolabeled for GAT-1. However, Purkinje cell axon terminals that formed symmetric synapses with neurons in the deep cerebellar nuclei lacked GAT-1 immunoreactivity. Instead, weak GAT-1 and strong GAT-3 immunoreactivities were expressed by astrocytic processes that enveloped the Purkinje cell axon terminals. In addition, GAT-3-immunoreactivity appeared in astrocytic processes in the cerebellar cortex. These observations demonstrate that GAT-1 is localized to axon terminals of three of the four neuronal types that were previously established as being GABAergic, i.e. basket, stellate and Golgi cells. GAT-1 and GAT-3 are expressed by astrocytes. The failure to identify a GABA transporter in Purkinje cells is consistent with previous data that indicated that Purkinje cells lacked terminal uptake mechanisms for GABA. The individual glial envelopment of Purkinje cell axon terminals in the deep cerebellar nuclei and the dense immunostaining of GAT-3, and to a lesser extent GAT-1, expressed by astrocytic processes provide a compensatory mechanism for the removal of GABA from the synaptic cleft of synapses formed by Purkinje cell axon terminals. SN - 0340-2061 UR - https://www.unboundmedicine.com/medline/citation/8896702/Astrocytic_processes_compensate_for_the_apparent_lack_of_GABA_transporters_in_the_axon_terminals_of_cerebellar_Purkinje_cells_ L2 - https://dx.doi.org/10.1007/bf00198540 DB - PRIME DP - Unbound Medicine ER -