Frustration stress (unexpected loss of alternative reinforcement) increases opioid self-administration in a model of recovery

Purpose: Engaging in alternative activities in the context where opioid use had occurred can constrain opioid use and helps to maintain recovery. However, "frustration stress" that occurs when contingencies on these alternative activities unexpectedly change (e.g., job loss or divorce) is thought to threaten recovery by prompting a return to drug use. Yet it remains unclear whether frustration stress can result in a return to drug use, and if so, whether it returns to prior levels or to even greater levels. Procedures: We examine the impact of unsignaled extinction of alternative reinforcement on opioid use. Rats were trained to respond for an etonitazene solution (5 mu g/ml, p.o.), then for food in alternating daily sessions. Subsequently, food and etonitazene were made concurrently available. Under concurrent availability conditions, rats were exposed to 1, 2, or 4 sessions of unsignaled food extinction, and effects on responding for etonitazene and food measured. Findings: When etonitazene was the only reinforcer available, rats earned 58.3 +/- 20.3 mu g/kg/session (mean +/- S.E.M.). When food was available in alternating sessions, etonitazene earned was unchanged (65.3 +/- 19.2 mu g/kg/session). Concurrent food availability decreased etonitazene earned (13.5 +/- 4.5 mu g/kg/session). Unsignaled food extinction returned etonitazene earnedto levels similar to (60.5 +/- 18.4 mu g/kg/session), but not greater than, those observed previously when etonitazene alone was available. Conclusions: Unsignaled extinction of alternative behavior controlling opioid use can result in increased opioid use, but this use does not rise beyond previous levels observed when opioid use is unconstrained by alternative reinforced behavior.