A, Representative immunofluorescence of internalized GluR1 in hippocampal neurons infected with lentivirus containing GFP or Arc-GFP (green). B, Quantification of internalized GluR1 puncta reveal that neurons with Arc-GFP expression have increased GluR1 endocytosis rate as compared to neurons expressing GFP only. Data from 3 cultures. C, Representative images of surface GluR1 staining in neurons infected with lentivirus containing GFP or Arc-GFP. Neurons were treated with media (control) or DHPG (100 µM, 5 min) and fixed one hour after onset of treatment. D, Quantification of surface GluR1 puncta number in GFP or Arc-GFP infected neurons treated with media (control) or DHPG reveal that Arc-GFP overexpression decreases basal surface GluR1 levels and blocks DHPG-induced decreases in surface GluR1. Data from 3 cultures. E, Representative images of surface GluR1 staining in neurons infected with lentivirus containing GFP or Arc-GFP. Neurons were treated with media (control) or NMDA and fixed one hour after onset of treatment. F, Quantification of surface GluR1 puncta number in GFP or Arc-GFP infected neurons treated with media (control) or NMDA reveal that Arc-GFP overexpression decreases basal surface GluR1 levels and blocks NMDA-induced decreases in surface GluR1. Data from 3 cultures. In all images scale bars = 10 µm.