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. 2012 Oct;167(3):537–547. doi: 10.1111/j.1476-5381.2012.02007.x

Figure 3.

Figure 3

Effects of spinally administered milnacipran (Mil) on the late maintenance phase of long-term potentiation (LTP) of C-fibre-evoked field potentials (FPs) in naïve animals and its reversal by antagonizing the effect of milnacipran. FPs in the spinal dorsal horn were elicited by electrical stimulation of the sciatic nerve fibres at 1 min intervals in anaesthetized naïve adult rats. LTP of C-fibre-evoked FPs was induced by high-frequency stimulation (HFS; 0.5 ms duration, 40–45 V, 100 Hz, given in two trains of 1 s duration at 20 s intervals; arrowhead) of the sciatic nerve fibres. Each area of C-fibre-evoked FPs was normalized to the mean of 60 consecutive responses obtained prior to HFS (−60 to 0 min in the graph) and five consecutive responses were averaged. Milnacipran (10 µM) was administered spinally in the late maintenance phase of LTP (190 min after HFS; white arrow). Milnacipran was removed from the chamber and replaced by yohimbine (Yoh; n= 3) or vehicle (n= 3) 120 min after the application of milnacipran (310 min after HFS; black arrow). Data shown are means ± SEM.