Figure 3.

NOP and NMDA receptors modulate recognition memory formation through common hippocampal ERK-dependent mechanisms. A, Western blots represent the phosphorylated and total forms of ERK2 30 min after the familiarization trial. Ro64-6198 (0.3 mg/kg) and MK-801 (0.01 mg/kg) were administered separately or concurrently before the familiarization trial (n = 2–3 mice per treatment represented). Histograms represent the mean percentage of change from the vehicle-treated group ± SEM for normalized pERK2 immunoreactivity for each pharmacological treatment (n = 4–6 per treatment). B, Coadministration of Ro64-6198 (0.3 mg/kg) and MK-801 (0.01 mg/kg) synergistically impairs long-term recognition memory (n = 7–8 per treatment). Data are represented as the mean discrimination index ± SEM. The dashed line shows a chance level of 50%. **p < 0.01, significantly different from vehicle-treated group and ^#significantly different from all other groups.