Ouabain induces memory impairment and alter the BDNF signaling pathway in an animal model of bipolar disorder: Cognitive and neurochemical alterations in BD model.

Background: The present study aims to evaluate the effects of ouabain on memory and neurotrophic parameters in the brains of rats.
Methods: Wistar rats received an intracerebroventricular (ICV) injection of ouabain or artificial cerebrospinal fluid (aCSF). Seven and 14 days after ICV administration, the animals were subjected to the open-field and splash tests. Furthermore, the pro-BDNF, BDNF, TrkB, and CREB were assessed in the frontal cortex and hippocampus of the rats, in both seven and 14 days after ICV injection. The memory of the animals was tested by novel object recognition test (NOR) and inhibitory avoidance task (IA), only 14 days after ICV administration.
Results: Ouabain increased locomotion and exploration in the animals seven days after its administration; however, 14 days after ICV, these behavioral parameters return to the basal level. Seven days after ouabain administration increased grooming behavior in the splash test; on the other hand, seven days after ouabain injection decreased the grooming behavior, which is considered an anhedonic response. Besides, ouabain decreased recognition index in the NOR and decreased aversive memory in the IA, when compared to the control group. The levels of pro-BDNF and BDNF decreased in the frontal cortex seven days after ouabain; but its receptor (TrkB) and CREB decreased seven and 14 days after ouabain, in both cerebral structures evaluated.
Conclusion: Ouabain-induced animal model of BD is an excellent model to assess memory alteration, observed in bipolar patients. Besides, the memory impairment induced by ouabain seems to be related to BDNF signaling pathway alterations.
(Copyright © 2021. Published by Elsevier B.V.)