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. 2003 Jun 19;139(8):1498–1504. doi: 10.1038/sj.bjp.0705378

Figure 4.

Figure 4

Effect of opioid receptor antagonists on local fentanyl-induced decrease in extracellular 5-HT in the DRN. The mean baseline level of extracellular 5-HT was 6.6±0.8 pg sample−1 (n=9). The open horizontal bar indicates the period of fentanyl infusion. Dotted lines show data replotted from Figure 3 for the effect of infusing fentanyl (100 μM) alone. (a) Arrow indicates the time of naltrexone injection. Systemic naltrexone (10 mg kg−1, s.c.) did not block the effect of local fentanyl (100 μM: F(1,9)=2.95, P=0.12). (b) The solid horizontal bar represents infusion of nor-BNI (300 μM). Pretreatment with nor-BNI had no significant effect on the fentanyl-induced decrease in 5-HT: F(1,8)=0.13, P=0.7299.