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. Author manuscript; available in PMC: 2008 Jul 1.
Published in final edited form as: Biochem Pharmacol. 2007 Jul 20;75(1):17–33. doi: 10.1016/j.bcp.2007.07.018

Figure 3.

Figure 3

A. Theoretical head twitch data illustrating low levels of this behavior following injection of saline (filled square), dose-dependent and biphasic effects of a test drug on this behavior (filled triangles), and a parallel rightward shift in this dose-effect curve produced by prior treatment with an antagonist (open triangles). Note that pretreatment with either an additive agonist or an antagonist would decrease the HTR induced by the peak dose of the test drug by functionally increasing or decreasing, respectively, the drug dose. These data emphasize the importance of full dose-effect curve determinations using this assay. B. Empirical head twitch data from mice injected with the tryptamine hallucinogen 5-MeO-DIPT, with or without prior treatment with the selective 5-HT2A antagonist M100907. The antagonist produces a parallel rightward shift in the dose effect curve. Figure replotted and modified slightly from data previously published in [29]; used with permission.