Estrous cycle variation in anxiolytic-like effects of topiramate in Wistar rats in two animal models of anxiety-like behavior.

The anxiolytic-like effects of topiramate were assessed during several estrous cycle phases in Wistar rats tested in two animal models of anxiety-like behavior. In a conflict operant test, during proestrus, diazepam (1.3, 2.0mg/kg; P<0.05) or topiramate (20.0, 30.0mg/kg; P<0.05) increased the number of immediately punished responses. During metestrus-diestrus only the highest doses of diazepam (2.0mg/kg, P<0.05) or topiramate (30.0mg/kg, P<0.05) increased the number of immediately punished reinforcers. Similar results were obtained in the elevated plus-maze test: during proestrus, diazepam (1.3, 2.0mg/kg; P<0.05) or topiramate (20.0, 30.0mg/kg; P<0.05) produced anxiolytic-like actions. During metestrus-diestrus only the highest doses of diazepam (2.0mg/kg, P<0.05) or topiramate (30.0mg/kg, P<0.05) produced anxiolytic-like actions. Neither diazepam nor topiramate nor estrous cycle phases significantly modified the number of closed arm entries in the elevated plus-maze test. It is concluded that the response to neuromodulatory drugs for anxiety-like behavior varied according to the estrous cycle phases.