Effects of chronic treatment with a water-alcohol extract from Erythrina mulungu on anxiety-related responses in rats.

We investigated the effects of chronic oral treatment with a water-alcohol extract from the inflorescence of Erythrina mulungu (Leguminosae-Papilionaceae) (EM, 50, 100, 200 mg/kg) in rats submitted to different anxiety models: the elevated T-maze (ETM, for inhibitory avoidance and escape measurements), the light/dark transition, and the cat odor test. These models were selected for their capacity to elicit specific subtypes of anxiety disorders as recognized in clinical practice. Treatment with EM impaired inhibitory avoidance latencies in a way similar to the reference drug, diazepam (DZP). Additionally, both EM and DZP increased the number of transitions and the time spent in the lighted compartment of the light/dark transition model. Furthermore, neither EM nor DZP altered behavioral responses of rats to a cloth impregnated with cat odor. In contrast to DZP, however, EM also altered ETM one-way escape. These results were not due to motor alterations since no significant effects were detected in the number of crossings or rearings in the arena. The present observations suggest that chronic EM exerts anxiolytic-like effects in defensive behaviors related to generalized anxiety and panic disorder. Although alkaloids appear to be one of the main constituents of EM, the possible mechanisms through which the extract exerts its anxiolytic action should be further investigated.