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. 2002 Jul 18;99(16):10276–10281. doi: 10.1073/pnas.102327699

Fig 4.

Fig 4.

The effect of CXCL12, CCL5, and CCL2 on the DAMGO-induced analgesic response in the rat PAG. (A) Rats were cannulated into the PAG, and SDF-1α was administered at the designated concentrations. After 30 min, DAMGO (400 ng) was administered, and the analgesic response, expressed as the percent maximum possible analgesia, in the cold-water tail-flick assay was determined. (B) Administration of designated concentrations of CXCL12, followed 30 min later with saline, did not show any evidence of detectable analgesia or hyperalgesia. Control experiments showed that the administration of saline, followed 30 min later with saline, also failed to show any evidence of analgesia (data not shown). CCL5 (C) or CCL2 (D) also was administered into the PAG at the designated concentrations. After 30 min, DAMGO (400 ng; solid symbols) or saline (□) was administered, and the analgesic response was determined. Results are presented as the mean ± SD and are representative of four independent experiments.