Fig. 5.
Endocannabinoid-mediated synaptic modulation elicited by either LFS or high-frequency stimulation (HFS) and the role of Cl− homeostasis. A, C, and E, top: example of changes in EPSP amplitude elicited by either the Npoly (A), P (C). or Nmech neuron (E; scale bars = 20.0 mV/50 ms), following LFS (A) or HFS (C and E; scale bars = 2.0 mV/50 ms for Npoly and P and 1.0 mV/50 ms for Nmech), LFS + BUM (A) or HFS + tetrahydrolipstatin (THL) (C, E;) (bottom; scale bars = 2.0 mV/50 ms). Black and gray traces are pre- and posttest EPSPs, respectively. B, D, and F: mean ± SE EPSP (%pretest amplitude) following LFS or HFS with or without SB, THL, VU, or BUM. B: in Npoly synapses, LFS elicited synaptic depression. This depression was not blocked by BUM. D: in P synapses, HFS elicited synaptic potentiation and this potentiation was blocked by SB, THL, and VU. (F) In Nmech synapses, HFS elicited synaptic depression and this depression was blocked by SB, THL, and BUM. For all 3 synapse types no change in EPSP amplitude was observed in the saline (no stim) or in the SB-, THL-, VU-, or BUM-only groups. *Statistically significant differences based on one-way ANOVA with Student-Newman-Keuls post hoc test (see results); n = 5 (different animals) for all treatment and control groups.