G-Protein Coupled Receptor-Evoked Glutamate Exocytosis from Astrocytes: Role of Prostaglandins
Figure 3
Pharmacological characterization of the receptor subtypes mediating exocytosis of VGLUT1-pHluorin positive vesicles in response to ATP and glutamate agonists. (a) TIRF image showing an astrocyte transfected with VGLUT1-pHluorin. Bar 20 nm. (b) Stereotyped sequence of pHluorin destaining reveals exocytosis of a VGLUT1-pHluorin positive vesicle. The sequential gray scale micrographs represent the fate of pHluorin before (−100 ms) and during (100, 200, 400 ms) the fusion event. Bars: 380 nm. The scheme shows the behaviour of pHluorin before and after fusion event. Note that the color code for the pHluorin fluorescence signal is gray when the signal is off and green when it is on. (c), (d) P2Y1 receptors mediate the ATP-evoked exocytosis. (c) Temporal distribution of fusion events evoked by ATP (100 μM). (d) Histograms represent the total number of fusion events evoked by ATP () that is strongly inhibited in the presence of the P2 purine antagonists PPADS (100 μM, ) as well as of the P2Y1-selective compound, A3P5PS (100 μM, ). Data are ± SEM of 4 cells. (e), (f) mGluR5 mediates the response to t-ACPD, in the presence of AMPA. (e) Temporal distribution of fusion events evoked by 50 μM t-ACPD+50 μM AMPA. (f) Histograms represent the total number of fusion events evoked by t-ACPD+AMPA () that is strongly inhibited in the presence of the mGluR antagonists, including the subtype-nonselective MCPG (500 μM, ) and the mGluR5-selective MPEP (200 nM, ). Data are ± SEM of 4 cells. Statistical significance of inhibition with receptor antagonists was calculated using t-test (**).
