Journal: Bio-protocol

Article Title: A Male Mouse Model of WIN 55,212–2 Self-Administration to Study Cannabinoid Addiction

doi: 10.21769/BioProtoc.5652

Figure Lengend Snippet: Complete experimental protocol of our mouse model of operant WIN 55,212–2 intravenous self-administration

Article Snippet: Mouse operant self-administration chambers (Med Associates, model: ENV-307A-CT) Operant chambers are equipped with two nose-poke holes (holes of 1.2 cm diameter), one randomly selected as the active nose poke and the other as the inactive.

Techniques:

Journal: Bio-protocol

Article Title: A Male Mouse Model of WIN 55,212–2 Self-Administration to Study Cannabinoid Addiction

doi: 10.21769/BioProtoc.5652

Figure Lengend Snippet: An intraperitoneal injection of WIN 55,212-2 (0.1 mg/kg) is administered 24 h before the first self-administration session to minimize the aversive effects of the initial cannabinoid exposure. During the first week of operant training, mice acquire WIN 55,212-2 self-administration under fixed-ratio (FR) schedules, with 5 sessions at FR1 followed by 5 sessions at FR2. Sessions 1–10 and 12 include a 15-min drug-free period (DFP), but only the latest 8–10 sessions are used to quantify persistence of responding, the first addiction-like criterion. In session 11, motivation for WIN 55,212-2 is assessed using a progressive-ratio (PR) schedule, providing the second criterion. FR2 session is then re-established in session 12 to stabilize responding before punishment testing. In session 13, compulsivity-like behavior is evaluated in a foot-shock punishment test, yielding the third diagnostic criterion and allowing classification of mice as addicted or non-addicted. Extinction training is conducted in sessions 14–23, and in session 24, a cue-induced reinstatement test is performed to probe relapse-like drug seeking and obtain the parameters related to craving.

Article Snippet: Mouse operant self-administration chambers (Med Associates, model: ENV-307A-CT) Operant chambers are equipped with two nose-poke holes (holes of 1.2 cm diameter), one randomly selected as the active nose poke and the other as the inactive.

Techniques: Injection, Diagnostic Assay

Journal: Bio-protocol

Article Title: A Male Mouse Model of WIN 55,212–2 Self-Administration to Study Cannabinoid Addiction

doi: 10.21769/BioProtoc.5652

Figure Lengend Snippet: Persistence was defined as non-reinforced active responses during the 15-min drug-free period across three days before the progressive-ratio (PR) session. Only the operant box house light is on during this period. Motivation was assessed with a PR schedule, with the breakpoint (last ratio completed before cessation of responding) taken as the motivation value. Only the conditioned-stimulus cue light and the drug delivery were active. Compulsivity was measured in a 50-min punished self-administration session under FR2, during which each infusion was paired with a 0.18 mA, 2 s foot shock, and the total number of shocks indexed resistance to punishment. The conditioned-stimulus cue light, the drug delivery, and the unconditioned stimulus of the grid floor delivering foot shocks were active. An overall addiction score was derived from these three behavioral measures.

Article Snippet: Mouse operant self-administration chambers (Med Associates, model: ENV-307A-CT) Operant chambers are equipped with two nose-poke holes (holes of 1.2 cm diameter), one randomly selected as the active nose poke and the other as the inactive.

Techniques: Derivative Assay

Journal: Bio-protocol

Article Title: A Male Mouse Model of WIN 55,212–2 Self-Administration to Study Cannabinoid Addiction

doi: 10.21769/BioProtoc.5652

Figure Lengend Snippet: Impulsivity-like behavior was quantified as the number of non-reinforced active responses emitted during the 10-s time-out period following each WIN 55,212-2 infusion, averaged across the 3 days preceding the progressive-ratio (PR) test (higher counts indicate greater difficulty inhibiting responding once initiated). Sensitivity to reward was assessed as the total number of reinforcers earned during 2-h sessions across the last three consecutive FR2 self-administration sessions maintained by WIN 55,212-2, with higher reinforcer counts reflecting greater reward sensitivity.

Article Snippet: Mouse operant self-administration chambers (Med Associates, model: ENV-307A-CT) Operant chambers are equipped with two nose-poke holes (holes of 1.2 cm diameter), one randomly selected as the active nose poke and the other as the inactive.

Techniques:

Journal: Bio-protocol

Article Title: A Male Mouse Model of WIN 55,212–2 Self-Administration to Study Cannabinoid Addiction

doi: 10.21769/BioProtoc.5652

Figure Lengend Snippet: Number of total active and inactive nose pokes performed by CNO- and saline-treated groups obtained during 2 h of operant self-administration maintained by intravenous infusions of WIN 55,212-2 in both FR1 and FR2 schedules of reinforcement (mean ± S.E.M., repeated measures ANOVA). Data derived from Cajiao et al., 2023 [7].

Article Snippet: Mouse operant self-administration chambers (Med Associates, model: ENV-307A-CT) Operant chambers are equipped with two nose-poke holes (holes of 1.2 cm diameter), one randomly selected as the active nose poke and the other as the inactive.

Techniques: Saline, Derivative Assay