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. 2001 Dec 15;21(24):9856–9866. doi: 10.1523/JNEUROSCI.21-24-09856.2001

Fig. 8.

Fig. 8.

Effects of the intravenous administration of DOI on serotonergic neurons of the DR. A–E, Integrated firing rate histograms showing the effect of DOI on five different 5-HT neurons. A–C depict neurons with full (A) and partial (B, C) inhibitory responses to the administration of cumulative doses of DOI (25–50 μg/kg, i.v. in A; 25–400 μg/kg, i.v. inB, C). The effect of DOI was antagonized by M100907 (100 μg/kg, i.v.; examples in B andD). The serotonergic nature of neurons with partial or full response to DOI is illustrated by its sensitivity to 8-OH-DPAT (C, D). D shows the inhibitory effect of DOI (25–50 μg/kg, i.v.). After reversal by M100907 (100 μg/kg, i.v.), 8-OH-DPAT (DPAT; 0.25–2 μg/kg, i.v.) fully suppressed firing activity, and the 5-HT1A receptor antagonist WAY 100635 (WAY; 10 μg/kg, i.v.) returned firing rate to baseline. E shows the reversal of the effect of DOI (25–200 μg/kg, i.v.) by the GABAAantagonist picrotoxinin (PTX; 1 mg/kg, i.v.). The graph inF shows the dose–response curves for DOI in 5-HT neurons. The neurons with partial and full inhibitory responses to DOI administration had comparable ED50 values (19 and 22 μg/kg, i.v.; n = 7 and 5, respectively). Thedotted line shows the dose–response curve for all neurons (n = 12).