The G protein biased serotonin 5-HT 2A receptor agonist lisuride exerts anti-depressant drug-like activities in mice

There is now evidence from multiple Phase II clinical trials that psychedelic drugs can exert long-lasting anxiolytic, anti-depressant, and anti-drug abuse (nicotine and ethanol) effects in patients. Despite these benefits, the hallucinogenic actions of these drugs at the serotonin 2A receptor (5-HT2AR) limit their clinical use in diverse settings. Activation of the 5-HT2AR can stimulate both G protein and {beta}-arrestin ({beta}Arr) -mediated signaling. Lisuride is a G protein biased agonist at the 5-HT2AR and, unlike the structurally-related LSD, the drug does not typically produce hallucinations in normal subjects at routine doses. Here, we examined behavioral responses to lisuride, in wild-type (WT), {beta}Arr1-KO, and {beta}Arr2-KO mice. In the open field, lisuride reduced locomotor and rearing activities, but produced a U-shaped function for stereotypies in both {beta}Arr lines of mice. Locomotion was decreased overall in {beta}Arr1-KOs and {beta}Arr2-KOs, relative to WT controls. Incidences of head twitches and retrograde walking to lisuride were low in all genotypes. Grooming was depressed in {beta}Arr1 mice, but was increased then decreased in {beta}Arr2 animals with lisuride. Prepulse inhibition (PPI) was unaffected in {beta}Arr2 mice, whereas 0.5 mg/kg lisuride disrupted PPI in {beta}Arr1 animals. The 5-HT2AR antagonist MDL100907 failed to restore PPI in {beta}Arr1 mice, whereas the dopamine D2/D3 antagonist raclopride normalized PPI in WTs but not in {beta}Arr1-KOs. Using vesicular monoamine transporter 2 mice, lisuride reduced immobility times in tail suspension and promoted a preference for sucrose that lasted up to 2 days. Together, it appears {beta}Arr1 and {beta}Arr2 play minor roles in lisurides actions on many behaviors, while this drug exerts anti-depressant drug-like responses without hallucinogenic-like activities.