The effects of carbamazepine on an appetitive-to-aversive transfer task: comparison to untreated and phenytoin.

1. Concerns over negative consequences resulting from chronic maintenance with antiepileptic medications have led to increased research regarding such impairments, often with disparate results. The authors have previously reported that phenytoin profoundly impairs the ability of adult rats, in comparison to controls. To learn a tone-signaled active avoidance response after learning a tone-signaled appetitive response (Banks et al., 1995; Banks et al., 1999). Such results lend further support to the suggestion that pharmacological treatment itself can produce cognitive difficulties that are comparable to those experienced by epileptic patients (Meador, 1994; Smith et al., 1987). 2. In the present experiments, the authors have continued their investigation of antiepileptic compounds by treating rats with carbamazepine, another commonly prescribed "first-line defense" antiepileptic medication. In comparison to intact animals, carbamazepine-treated rats demonstrate variable deficiencies in the acquisition of the secondarily acquired avoidance response. 3. This result is in agreement with the finding for phenytoin-treated animals, albeit to a lesser degree. Continuing experiments are needed to investigate the relative nature of the deficits produced by such antiepileptic medications, as well as the underlying neurobiological mechanism(s).