Table 5.

Functional Selectivity Demonstrated in βarrestin2-KO Mice

Proposed Target	Drug/Challenge	Behavior Phenotype	Reference
Mu opioid receptor	Morphine Heroin	Enhanced and prolonged antinociception	Bohn et al., 1999; 2000; 2004b
	Etorphine, Fentanyl, Methadone	No differences in antinociception	Bohn et al., 2004b
Serotonin 2A receptor	5-hydroxy-L-tryptophan	Reduced head twitch response	Schmid et al., 2008
	DOI	No difference in head twitch response	Schmid et al., 2008

DOI: (±)-2,5-Dimethoxy-4-iodoamphetamine hydrochloride