Fig. 7.

mGluR5 antagonist does not change inhibition of a mPFC neuron in arthritis pain. Extracellular recordings of the responses of 1 mPFC neuron to brief (15 s) innocuous and noxious stimulation of the knee and background activity. A: time-course data show the decrease in activity after arthritis induction and the lack of effect of a selective mGluR5 antagonist [2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), 100 μM; concentration in microdialysis fiber, 15 min] administered into the mPFC. ACSF was administered as vehicle control before (predrug) and after MPEP. B–E: peristimulus time histograms show action potentials (spikes)/s. Insets show individual action potentials. Top traces are recordings of the force (g/30 mm²) applied to the knee joint.