Figure 3

Presynaptic μ-opioid inhibition predominates during menthol enhanced glutamatergic transmission. (a) Time plot of miniature EPSC (mEPSC) rate during superfusion of menthol (400 μM), then during addition of deltorphin-II (Delt, 300 nM), ICI-174864 (ICI, 1 μM), U69593 (U69, 300 nM), nor-BNI (300 nM), DAMGO (3 μM) and naloxone (Nalx, 1 μM). (b) Averaged traces and (c) raw current traces of mEPSCs prior to (Pre), and during menthol, then during addition of deltorphin-II, U69593 and DAMGO. Inset in (c) is an expanded part of the trace to show summation of mEPSCs in the presence of menthol. Cumulative probability distribution plots of mEPSC (d) inter-event interval and (e) amplitude for the epochs averaged in (b) (number of events = 648, 1597, 1540, 1259, 506 for control, menthol, deltorphin-II, U69593 and DAMGO over 80, 40, 40, 40 and 80 s intervals, respectively). (a) - (e) are taken from one neuron.