Two important control conditions were included in the acute treatment experiment. Because FN-439 was administered prior to and following the self-administration sessions, the possibility existed that FN-439 could have rate-decreasing effects that are independent of a MMP mechanism of action. Therefore, a failure to observe elevated self-administration during acute withdrawal could actually be a result of the FN-439 pretreatment and unrelated to the blockade of learning. Thus, the first control condition received an acute ICV FN-439 pretreatment 15 min prior to a final self-administration session following stable elevated ethanol self-administration in the aCSF-treated group. The second control condition was designed to address the possibility that FN-439 exposure might induce a permanent alteration in an organism's capacity to develop an escalated ethanol self-administration pattern during acute withdrawal when dependent. Once the FN-439 infusions were terminated for the FN-439 acute treatment group, the animals continued to receive aCSF infusions under the same timing conditions as the FN-439 treatments (i.e., 15 min prior to and 45 min. after) to evaluate whether the animals would show normal negative reinforcement learning. A diagram describing the treatment regimens for conditions 2 and 3 is presented in Figure 1.
