Figure 9.

A, C, Upregulation of spinal NR1 (A) and PKCγ (C) expression after chronic morphine (10 μg) was blocked by coadministration of morphine with the AC inhibitor ddA (1 μg) or PKA inhibitor H89 (10 μg), given intrathecally twice daily for 6 d. The ddA or H89 treatment alone did not affect baseline NR1 or PKCγ expression. The AC activator forskolin (10 μg, i.t.; twice daily for 6 d) alone induced the NR1 and PKCγ expression within the spinal cord dorsal horn, and the combined treatment with morphine (10 μg) and forskolin (10 μg) further enhanced NR1 and PKCγ expression. B, D, Statistical data for A and C. E, The same forskolin (10 μg) treatment alone also induced spinal GR expression, and the combined treatment with morphine (10 μg) and forskolin (10 μg) further enhanced GR expression. F, Statistical data for E. S, Saline; V, vehicle; M, morphine; MD, morphine plus ddA; D, ddA alone; MF, morphine plus forskolin; F, forskolin alone; MH, morphine plus H89; H, H89 alone. ^*p < 0.05 compared with the vehicle group; ⁺p < 0.05 compared with both vehicle and morphine-alone groups.