Figure 2

Application of CB₁-R agonist amplifies intracellular calcium transients of astrocytes within the superficial spinal dorsal horn. (a–c) Records obtained with simultaneous loose patch recording (upper trace) and calcium imaging (lower trace) of a single cell. Application of 1 µM TTX (blue bar) diminishes both action potentials and calcium transients. The segment of the recording outlined in a is shown in b with an expanded time scale. The single event indicated by an arrow in a is shown expanded in c. (d) Records obtained with simultaneous loose patch recording (upper trace) and calcium imaging (lower trace) of a single cell. Slow calcium transients are not coupled to action potentials. (e,f) Confocal images of at low (e) and high (f) magnifications of a cell labeled intracellularly with biocytin from which action potential-uncoupled slow calcium transients were recorded. Scale bars: 20 µm (e) and 10 µm (f). (g,h) Six minutes long records illustrating changes in [Ca²⁺]_i of cells showing slow calcium transients in wild type (g) and CB₁-R knock out (h) mice, during treatment with 1 µM TTX (first 2 minutes), and 1 µM TTX + 1 µM WIN (last 4 minutes). The application of WIN increases both the frequency and amplitude of spontaneous slow calcium transients in the wild type (g) but not in the CB₁-R knock out (h) animals. (i,j) Box-plots of average areas under the curves of intracellular calcium transients recorded from cells showing slow calcium transients in wild type (i) and CB₁-R knock out (j) mice during TTX and TTX + WIN application.