Nociceptive response of PrP+/+ and PrP-/- mice in response to NMDA treatment. (A) Nociceptive response of wild type or PrPc null mice following intrathecal injection of NMDA (30 pmol/i.t. or 300 pmol/i.t.). Each column represents the mean + S.E.M. (n = 5-6). *P < 0.05. (B) Effect of MK-801 on the pain behaviour induced by intrathecal injection of NMDA (30 pmol). Each column represents the mean ± S.E.M. Control data (hatched bars) were obtained following i.t. injection of 5 μl PBS (i.e., the same route of delivery as for NMDA). NMDA data were obtained either following i.p. injection of 10 ml/kg PBS (black bars) or 0.005 mg/kg MK-801 (white bars). In this case, PBS serves as a control for MK-801. (n = 6-9). *P < 0.05, **P < 0.01.