Figure 9

Blockade of mGluR1 restores facilitatory effects of bicuculline on excitatory transmission in the arthritis pain model. (A) LY367385 (10 μM) decreased I/O function of excitatory synaptic transmission significantly (n = 5 neurons, P < 0.0001, main effect of drug, two-way ANOVA; see Results). Coapplication of bicuculline (10 μM) partially reversed the inhibitory effect of LY367385 (n = 5 neurons, P < 0.001, main effect of drug, two-way ANOVA; see Results). Current traces of EPSCs recorded in one CeLC neuron in a brain slice from an arthritic rat before (Predrug) and during application of LY367385 alone and together with bicuculline. Scale bars, 50 pA, 10 ms. (B) Current-clamp recordings show that LY367385 (10 μM) decreased the number of synaptically evoked action potentials in CeLC neurons in slices from arthritic rats (n = 5 neurons, P < 0.05, ANOVA with Bonferroni posttest). The addition of bicuculline (10 μM) partially reversed the inhibitory effect of LY367385 (n = 5 neurons, P < 0.05, ANOVA with Bonferroni posttest). Bar histograms show the number of spikes per 10 synaptic stimuli at near-threshold stimulus intensity averaged across the sample of neurons. Original traces show action potentials and excitatory postsynaptic potentials evoked in an individual CeLC neuron in a slice from an arthritic rat. Scale bars, 20 mV, 5 ms. (A, B) Symbols and error bars represent means ± SE.