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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Behav Pharmacol. 2011 Dec;22(8):785–793. doi: 10.1097/FBP.0b013e32834d13a2

Figure 5.

Figure 5

Effects of selected doses of morphine administered alone and in combination with JNJ (top panels) and MPEP (bottom panels) in the capsaicin procedure. These two doses of morphine were selected as they produced minimal (1.0 mg/kg: left most panels) and moderate (3.0 mg/kg: right most panels) antihyperalgesic effects when administered alone, thus allowing for the identification of potential enhancement of morphine antihyperalgesia. Morphine alone was tested in 11–13 rats, in combination with the two lower doses of JNJ and MPEP in 4–8 rats: due to toxic effects, dose combinations with the highest dose of JNJ and MPEP with morphine were limited to 2–4 rats. Vertical axis: antihyperalgesia expressed as the % of maximal possible effect. Horizontal axis: doses of morphine alone and in combination with JNJ or MPEP determined using an acute dosing procedure and expressed in mg/kg. Vertical bars represent the standard error: asterisks indicate a significant (P<0.05) difference from morphine alone.