GRN-529 chemical structure, plasma and brain concentrations, and receptor occupancy in B6, BTBR, and C58 mice. (A) Chemical structure of GRN-529 and binding properties [Ki = 5.4 nM and median inhibitory concentration (IC50) = 3.1 nM] at rat mGluR5. (B to D) Unbound plasma and brain concentrations of GRN-529 30 or 60 min after systemic administration in B6, BTBR, and C58 mice. s.c., subcutaneously; i.p., intraperitoneally. (E) Time course of unbound plasma and brain concentrations (nM) of GRN-529 for 2 hours after systemic intraperitoneal administration in B6 mice. (F) Relationship of the concentration of unbound (Cb,u) GRN-529 concentrations (nM) and mGluR5 occupancy in brains from BTBR, B6, and C58 mice. n = 3 to 5 per dose and strain. Data are expressed as the mean for each group.