Fig. 6: The ability of blocking A2AR immediately after contextual fear conditioning to normalize the increased long-term potentiation are independent of A1R in the dorsal hippocampus but not in the lateral amygdala.
From: Adenosine A2A receptors control generalization of contextual fear in rats
A, E Time-course of the variation, expressed as percentage of baseline values, of the slope of field excitatory post-synaptic potentials (fEPSPs) in the CA1 stratum radiatum upon stimulation of the afferent Schaffer collateral fibers (A) or of the amplitude of population spikes in synapses of the lateral amygdala (E), upon exposure to increasing concentrations of 2-chloroadenosine (CADO) in slices of rats receiving vehicle or SCH58261 (0.1 mg/kg), i.p., immediately after contextual fear conditioning (CFC - 3 shocks of 0.7 mA), corresponding to the groups labeled as CFC-veh (black circles) and CFC-SCH (black squares), or exposure to the conditioning chamber (context A) without application of electrical shocks, corresponding to the groups labeled as veh (gray circles) and SCH (gray squares). B, F The CADO concentration-dependent inhibition of fEPSPs or population spikes (and the fitted sigmoids constrained at 0 and 100%) indicate a lower efficiency of A1R after CFC, irrespective of the exposure to SCH58261 in the DH (B), but no modification of A1R efficiency in the LA (E). C, G The disinhibition by the A1R antagonist, DPCPX (100 nM), of synaptic transmission is not modified by CFC or SCH58261 in the DH (C), whereas it is abolished by SCH58261 exposure in the LA, irrespective of CFC (G). D, H LTP magnitude in the DH was reduced by CFC and restored by exposure to SCH58261, irrespective of the absence of presence of DPCPX (D), whereas in the LA the magnitude of LTP was increased by exposure to SCH58261 in the absence, but not in the presence of DPCPX (H). Values are expressed as mean ± SEM of n = 5–7 rats; * indicates a significant difference (p < 0.05) in relation to the value of 1 for C (one sample t test, comparing with a hypothetical value). # indicates a significant difference (p < 0.05) between the indicated groups, observed with two-way ANOVA followed by Fisher’s LSD multiple comparison test.
