British journal of pharmacology
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Comparative Study
The contribution of NMDA receptor activation to spinal c-Fos expression in a model of inflammatory pain.
1. Intraplantar carrageenin (6 mg 150 microliters-1) evoked a high level of spinal c-Fos expression in the dorsal horn, of segments L4-L5 of the spinal cord, and an extensive peripheral oedema; both parameters were assessed 3 h after carrageenin. 2. Two series of experiments were performed, with the mean total number of Fos like-immunoreactive neurones (Fos-LI), after carrageenin, not being significantly different for the two series of experiments (266 +/- 17 and 332 +/- 31 Fos-LI neurones). ⋯ A single post-administration of (+)-HA966 (10 mg kg-1), 45 min after intraplantar carrageenin, did not significantly influence the number of Fos-LI neurones in the superficial, deep laminae or ventral horn, but significantly reduced the number of Fos-LI neurones in the nucleus proprius, as compared tocontrol carrageenin expression (39+-/8% reduction of control carrageenin c-Fos expression, P <0.05).9 None of the concentrations of (+)-HA966 studied, irrespective of the timing of administration,influenced the peripheral carrageenin oedema. Our results illustrate a contribution of central NMDA receptor activation to carrageenin-evoked spinal c-Fos expression. These results extend previous studies demonstrating the contribution of the NMDA receptor to central hyperalgesia and the expression of c-Fos.