Fig. 1: Blockade of A_2AR immediately after contextual fear conditioning increases fear consolidation and accelerates fear generalization.

A Scheme of the experimental design. Vehicle or SCH58261 (0.1 mg/kg) were administered intraperitoneally (i.p.) immediately after contextual fear conditioning (CFC - 3 shocks of 0.7 mA). B Individual values and mean ± SEM (n = 9–11) of the percentage of time freezing in context A (paired with foot-shocks) or in the unpaired context B, at 1 and 2 days after conditioning, respectively. C Discrimination index of CFC animals at 1 and 2 days after conditioning; when probed for recent fear memory, SCH58261-injected rats had a lower discrimination index compared with the saline (control) group, showing a worst ability to distinguish between contexts A and B. D Scheme of the experimental design, where vehicle or SCH58261 (0.1 mg/kg) were administered i.p. immediately after a weak CFC protocol (1 shock of 0.5 mA). E Individual values and mean ± SEM (n = 10) of the percentage of time freezing in the paired context A or in the unpaired context B, at 1 and 2 days after CFC, respectively. F Discrimination index of rats subjected to a weak CFC, probed at 1 and 2 days after conditioning. Only the animals that were injected with SCH58261 after CFC discriminated between contexts A and B when probed for recent fear memory. B, E *p < 0.05 and ***p < 0.01 compared to the control group, treated with vehicle (two-way ANOVA followed by Fisher’s LSD multiple comparison test); C, F **p < 0.01, compared to the group treated with vehicle (Student’s t test) and ^#p < 0.05 or ^##p < 0.01, one sample t test comparing with the hypothetical value of 0.5 (i.e., no discrimination between contexts A and B).