Figure 1.

Electrically evoked tritium overflow from superfused hippocampal and striatal slices from CB₁^+/+ (empty columns) and CB₁^−/− mice (filled columns). Tritium overflow was evoked after 40 min of superfusion (S₁; and again after 90 min, not shown). Hippocampal slices from male CB₁^+/+ and CB₁^−/− mice were preincubated with [³H]-choline and then superfused with medium (Ca²⁺ 3.25 mM) containing hemicholinium-3 10 μM; stimulation parameters were 3 Hz, 200 mA, 2 ms. The results of this series (standard condition) are depicted in A. In additional series (A and B), (i) the Ca²⁺ concentration was lowered, (ii) slices from female mice were used, (iii) a muscarinic receptor antagonist (AF-DX 384) was present in the medium, (iv) striatal slices were used or (v) hippocampal slices preincubated with [³H]-noradrenaline were used. In the latter series, superfusion was carried out with medium (Ca²⁺ 1.3 mM) containing desipramine 1 μM and rauwolscine 1 μM and the stimulation parameters were 0.3 Hz, 50 mA, 2 ms. Data are expressed as means±s.e.mean of 5 – 14 experiments. ^*P⩽0.05, ^**P<0.005.