Figure 7. Changes in adenosine A_2A receptor expression in MPTP-treated mice.

CX₃CR1^GFP/+ mice were treated with 20 mg/kg s.c. MPTP or saline once daily for 5 days, and brains were isolated for analysis 5 days later. A, Adenosine A_2A receptor expression in the substantia nigra was detected with immunofluorescence. Microglia were identified without staining from the expression of GFP from the CX₃CR1 promoter. Approximate borders between SNc and SNr are given with dashed lines based on microglial cell density. Scale bar: 30 μm. B, Adenosine A_2A receptor expression in the substantia nigra as detected with DAB precipitation. Scale bar: 200 μm. C, Upregulation of A_2A receptor expression in the SNr following MPTP treatment was quantified by measuring the average Texas Red fluorescence signal. D, For comparison, the A_2A receptor signal in the striatum is shown. Even after upregulation in the SN, A_2A receptor is not expressed at the levels of the striatum. Scale bar: 30 μm. E, Quantification of A_2A receptor expression in the striatum following MPTP treatment by measuring the average Texas Red fluorescence signal. Statistics: two-tailed Student’s t test. *, p < 0.05.