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

Figure 1.

Figure 1

Effect of systemic fentanyl on extracellular 5-HT in the DRN of freely behaving rats: mean baseline level of extracellular 5-HT was 5.6±0.8 pg sample−1 (n=25). (a) Fentanyl produced a dose-dependent increase in 5-HT: F(3,20)=4.95, P=0.0094. The 0.2 mg kg−1 dose and asterisks indicating significance were omitted from the graph for the sake of clarity. (b) AUC values expressed as the cumulative increase above baseline from 0 to 2 h after fentanyl administration. The effect was significant as determined by analysis of AUC values (F(4,23)=6.37, P=0.0013). *P<0.05, compared to vehicle.