Figure 7. NG2 cells express mGluRs.

(A₁) The group I mGluR agonist 3,5-DHPG (100 µM, 11 s) produced [Ca²⁺]_i increases (upper trace) but not membrane currents (bottom). (A₂) Pre-application of LY341495 (10 µM, 11 s) followed by co-application of 3,5-DHPG (10 µM, 11 s) completely blocked the 3,5-DHPG-induced [Ca²⁺]_i elevation. Three min later, 3,5-DHPG (10 µM, 11 s) again provoked a [Ca²⁺]_i elevation in the same cell. (B₁) Region of interest with five NG2/EYFP cells (bar, 20 µm) which was selected for focal application of Fluo-4 AM (B₂). Arrows mark NG2 cells from which [Ca²⁺]_i elevations were recorded (also seen in C₁). Note Fluo-4 labeled, EYFP-negative cells located in the lower left corner. (C₁–C₃) [Ca²⁺]_i elevations upon 3,5-DHPG in the presence (middle) and absence (left, control; right, wash) of subtype-specific mGluR antagonists. Antagonists were pre-applied for 23 s, followed by 11 s co-application with 3,5-DHPG (10 µM, gray boxes). Applications were separated by 3 min. (C₁) The mGluR1 specific antagonist 3-MATIDA (50 µM) mostly exerted partial block of Ca²⁺-responses. (C₂) In most cells, 3,5-DHPG-mediated [Ca²⁺]_i elevations were abolished by the mGluR5 specific antagonist, MPEP (20 µM). (C₃) In a few cells, co-application of both antagonists failed to inhibit 3,5-DHPG-induced [Ca²⁺]_i elevations. Experiments shown in (C₁–C₃) were performed in the presence of the blocking cocktail described in the text. Each row represents one individual brain slice.