Assessing behavioral reallocation after acute environmental manipulations using an asymmetric cocaine versus sucrose choice task in male and female rats.

RATIONALE: Maladaptive drug choice is a defining component of substance use disorders; whereby drug misuse persists despite adverse consequences. A goal of behavioral interventions, such as contingency management programs, is to promote reallocation of behavior towards adaptive pursuits. The neurobiological mechanisms that govern behavioral reallocation in the context of ongoing cocaine use remain poorly understood.

OBJECTIVE

Here, we demonstrate a cocaine versus sucrose choice paradigm in male and female rats using a novel format that dissuades exclusive sucrose or cocaine choice by offering sucrose pellets on a progressive ratio, while cocaine infusions are offered at a low, fixed ratio. Maintenance of both drug and non-drug choice will allow for the investigation of behavioral reallocation following environmental or pharmacological manipulations. MATERIALS AND

METHODS

In experiment 1, rats were trained to perform the choice task and were tested under conditions of acute food restriction followed by cocaine non-reward (extinction). In experiment 2, rats were trained to perform the choice task and then subject to a cocaine punishment contingency, whereby cocaine choice was punished by an aversive white noise (AWN).

RESULTS

Rats display cocaine dose- and sucrose price-dependent choice preference with no apparent sex differences. However, after either 24 h of food restriction or removal of the cocaine reinforcer, male rats reallocate behavior towards sucrose, while female rats do not. Likewise, AWN-punished cocaine choice drives reallocation towards sucrose in male rats, but not females.

CONCLUSION

Our data suggest that male and female rats exhibit unique reallocation strategies in response to changing contingencies.