A Novel Assay Allowing Drug Self-Administration, Extinction, and Reinstatement Testing in Head-Restrained Mice

Abstract

Multiphoton microscopy is one of several new technologies providing unprecedented insight into the activity dynamics and function of neural circuits. Unfortunately, some of these technologies require experimentation in head-restrained animals, limiting the behavioral repertoire that can be integrated and studied. This issue is especially evident in drug addiction research, as no laboratories have coupled multiphoton microscopy with simultaneous intravenous drug self-administration, a behavioral paradigm that has predictive validity for treatment outcomes and abuse liability. Here, we describe a new experimental assay wherein head-restrained mice will press an active lever, but not inactive lever, for intravenous delivery of heroin or cocaine. Similar to freely moving animals, we find that lever pressing is suppressed through daily extinction training and subsequently reinstated through the presentation of relapse-provoking triggers (drug-associative cues, the drug itself, and stressors). Finally, we show that head-restrained mice will show similar patterns of behavior for oral delivery of a sucrose reward, a common control used for drug self-administration experiments. Overall, these data demonstrate the feasibility of combining drug self-administration experiments with technologies that require head-restraint, such as multiphoton imaging. The assay described could be replicated by interested labs with readily available materials to aid in identifying the neural underpinnings of substance use disorder.

An opioid-gated thalamoaccumbal circuit for the suppression of reward seeking in mice

“… a – c Behavioral design ( a ; image modified from Vollmer et al, 2021 71 ), schematic ( b ), and grouped data ( c ) for sucrose self-administration ( n = 13 mice; two-way ANOVA, lever: F 1,24 = 60.65, P < 0.001). d – f TMT ( d ), yohimbine ( e ), and extinction ( f ) suppressed lever pressing ( n = 13 mice; TMT: two-tailed t -test t 12 = 5.54, P = 0.001; yohimbine: t 12 = 5.66, P = 0.001; extinction: t 12 = 2.72, P = 0.02).…”

“…Following at least 2 normal acquisition sessions (no stressors), mice were given daily 1 h sessions wherein active lever pressing no longer resulted in cue or sucrose delivery until extinction criteria were reached. Extinction criteria were determined a priori 71 , as (1) at least 10 days of extinction training and (2) 2 of the last 3 days at a maximum of 20% active lever pressing rate as compared with the last 2 days of acquisition.…”

“…Opioid use disorder is associated with maladaptive reward-seeking behaviors despite negative consequences [33][34][35][36] 71 ). d Raster plot showing example active lever pressing rates in each group during sucrose selfadministration (examples from 5 mice/group; yellow bar = light on).…”

A thalamostriatal parvalbumin interneuron circuit suppresses risky reward-motivated behaviors and is disengaged by opioids

“…Self-administration: Experiments involving sucrose self-administration were performed based on a previous study wherein we developed a model of natural-and drug-reward seeking in head-restrained mice, enabling simultaneous two-photon calcium imaging 59 . After recovery from surgery, mice were habituated to head fixation during 30-minute sessions wherein levers were not presented.…”

“…Following at least 2 normal acquisition sessions (no stressors), mice were given daily 1-hour sessions wherein active lever pressing no longer resulted in cue or sucrose delivery until extinction criteria were reached. Extinction criteria were determined a priori 59 , as (1) at least 10 days of extinction training and (2) 2 of the last 3 days at a maximum of 20% active lever pressing rate as compared with the last 2 days of acquisition.…”