Glutamatergic and purinergic receptor-mediated calcium transients in Bergmann glial cells.
Astrocytes respond to neuronal activity with [Ca2+]i increases after activation of specific receptors. Bergmann glial cells (BGs), astrocytes of the cerebellar molecular layer (ML), express various receptors that can mobilize internal Ca2+. BGs also express Ca2+ permeable AMPA receptors that may be important for maintaining the extensive coverage of Purkinje cell (PC) excitatory synapses by BG processes. Here, we examined Ca2+ signals in single BGs evoked by synaptic activity in cerebellar slices. Short bursts of high-frequency stimulation of the ML elicited Ca2+ transients composed of a small-amplitude fast rising phase, followed by a larger and slower rising phase. The first phase resulted from Ca2+ influx through AMPA receptors, whereas the second phase required release of Ca2+ from internal stores initiated by P2 purinergic receptor activation. We found that such Ca2+ responses could be evoked by direct activation of neurons releasing ATP onto BGs or after activation of metabotropic glutamate receptor 1 on these neurons. Moreover, examination of BG and PC responses to various synaptic stimulation protocols suggested that ML interneurons are likely the cellular source of ATP.
Piet
Richard
R
Vollum Institute, Oregon Health & Science University, Portland, Oregon 97239, USA.
Jahr
Craig E
CE
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D009457:Neuroglia / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017470:Receptors, Glutamate / Q000502:physiology*; D011983:Receptors, Purinergic / Q000502:physiology*
D017470:Receptors, Glutamate; D011983:Receptors, Purinergic