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. Author manuscript; available in PMC: 2006 Apr 17.
Published in final edited form as: Pain. 2005 Aug;116(3):276–288. doi: 10.1016/j.pain.2005.04.014

Fig. 4.

Fig. 4

Sustained morphine up-regulates spinal NK-1 receptors. Tissue from placebo-treated rats is shown in the left column, and that from morphine-treated rats is shown in the right column. No apparent differences in NK-1 receptor immunoreactivity is seen between the spinal sections obtained from placebo-treated and morphine-treated rats 2 days after pellet implantation (A, B). The staining intensity of NK-1 receptors in tissues from morphine-treated rats on day 6 is enhanced compared to placebo-treated rats on day 6 (C, D). The enhanced staining is apparent in both laminae I/II and in deeper laminae. Scale bar, 200 μm.