R26 lsl tdtomato reporter mice

Male and female mice, 2 to 3 months of age, were used in accordance with institutional guidelines. All experiments were approved by the Mayo Clinic Animal Care and Use Committee. Heterozygous (CX3CR1^GFP/+) mice expressing GFP under the control of the fractalkine receptor (CX3CR1) were used for all experiments^{51 (link)}. P2Y₁₂^−/− mice were originally donated by Dr. Michael Dailey at the University of Iowa (Iowa City, IA, USA). Heterozygous R26-LSL-Gi-DREADD mice (“Gi DREADD,” Jax #026219), transgenic VGAT-ChR2 (Jax #014548) mice, and R26-LSL-tdTomato reporter mice (“td-Tomato”, Jax #007909) were purchased from the Jackson Laboratory (ME, USA). Heterozygous Gi-DREADD mice were bred to homozygous CX3CR1^GFP/GFP mice to obtain Gi-DREADD positive and negative (sibling “Control”) offspring for experiments. Transgenic VGAT-ChR2 mice were also bred to homozygous CX3CR1^GFP/GFP mice to obtain offspring with (“TG”) and without (“non-TG” control) transgene expression. Finally, P2Y₁₂^−/− mice were bred to P2Y₁₂^−/−: CX3CR1^GFP/GFP mice to obtain P2Y₁₂^−/−: CX3CR1^GFP/+ animals for imaging studies. Thy1-YFP mice (Jax #003782) were bred to CX3CR1^GFP/GFP to obtain Thy1-YFP: CX3CR1^GFP/+ in order to observe physical interaction between microglial processes and neuronal dendrites. Animals used for all experiments were randomly selected.