Inositol 1,4,5-trisphosphate signaling maintains the activity of glutamate uptake in Bergmann glia.
The maintenance of synaptic functions is essential for neuronal information processing in the adult brain. Astrocytes express glutamate transporters that rapidly remove glutamate from the extracellular space and they play a critical role in the precise operation of glutamatergic transmission. However, how the glutamate clearance function of astrocytes is maintained remains elusive. Here, we describe a maintenance mechanism for the glutamate uptake capacity of Bergmann glial cells (BGs) in the cerebellum. When inositol 1,4,5-trisphosphate (IP(3) ) signaling was chronically and selectively inhibited in BGs in vivo, the retention time of glutamate around parallel fiber-Purkinje cell synapses was increased. Under these conditions, a decrease in the level of the glutamate/aspartate transporter (GLAST) in BGs was observed. The same effects were observed after chronic in vivo inhibition of purinergic P2 receptors in the cerebellar cortex. These results suggest that the IP(3) signaling cascade is involved in regulating GLAST levels in BGs to maintain glutamate clearance in the mature cerebellum.
Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Masato
M
Mashimo
Yohei
Y
Okubo
Toshiko
T
Yamazawa
Miwako
M
Yamasaki
Masahiko
M
Watanabe
Toshihiko
T
Murayama
Masamitsu
M
Iino
D027322:Amino Acid Transport System X-AG / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology; D018698:Glutamic Acid / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D000072181:Inositol Polyphosphate 5-Phosphatases; D051379:Mice; D008810:Mice, Inbred C57BL; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D015290:Second Messenger Systems / Q000502:physiology*; D013569:Synapses / Q000502:physiology
D027322:Amino Acid Transport System X-AG; D018698:Glutamic Acid; D015544:Inositol 1,4,5-Trisphosphate; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D002118:Calcium