Fig. 2

CB1R activation does not alter extracellular glutamate. (a) Voltage-clamp recording from a L2/3 pyramidal neuron at +30 mV. Left, ACEA (1 µM) was applied for 2.5 min prior to D-AP5 (50 µM). Right, after washout of ACEA and D-AP5, application of NMDA (5 µM) elicited an outward current. Dashed line denotes baseline. (b) Left, the current blocked by D-AP5 when ACEA (grey symbols, n = 8 cells from 2 mice) or vehicle (black symbols, n = 15 cells from 3 mice) was applied for 2.5–3 min prior to D-AP5 (P = 0.34). Right, the NMDA-induced currents were also similar (P = 0.25). The red open symbols correspond to the example traces shown in (a). (c) The extracellular glutamate concentration was the same in ACEA and vehicle (24.5 ± 3.2 nM versus 27.0 ± 2.6 nM, P = 0.57). (d) As in (b), with 5 µM WIN (grey symbols, n = 13 cells from 3 mice) versus vehicle (black symbols, n = 13 cells from 5 mice; D-AP5-sensitive current: P = 0.34; NMDA current: P = 0.34). (e) The extracellular glutamate concentration was the same in WIN and vehicle (25.5 ± 4.1 nM versus 27.9 ± 4.9 nM, P = 0.70). (f) Voltage-clamp recording from a L2/3 pyramidal neuron at + 30 mV. TBOA (100 µM) led to an outward current. After washout, TBOA and WIN (5 µM) were applied together. (g) Current in TBOA alone or in TBOA + WIN (n = 10 cells from 5 mice, P = 0.18). The red open symbols correspond to the example shown in (f). (h) Current in TBOA alone or in TBOA + vehicle (n = 12 cells from 6 mice, P = 0.31). (i) Currents obtained in the presence of WIN or vehicle normalized to the currents measured in TBOA only (P = 0.98). The red open symbols in (g) and (i) correspond to the example shown in (f). The experiments summarized in g and h were analyzed using paired t-tests. All other comparisons were done with unpaired t-tests.