Evaluation of brain creatine kinase activity in an animal model of mania induced by ouabain

Bipolar disorder (BD) is a common and severe mood disorder associated with higher rates of suicide and disability. The development of new animal models, and the investigation employing those available have extensively contributed to understand the pathophysiological mechanisms of BD. Intracerebroventricular (i.c.v.) administration of ouabain, a specific Na⁺,K⁺-ATPase inhibitor, has been used as an animal model for BD. It has been demonstrated that Na⁺,K⁺-ATPase is altered in psychiatric disorders, especially BD. Creatine kinase (CK) is important for brain energy homeostasis by exerting several integrated functions. In the present study, we evaluated CK activity in the striatum, prefrontal cortex and hippocampus of rats subjected to i.c.v. administration of ouabain. Adult male Wistar rats received a single i.c.v. administration of ouabain (10⁻² and 10⁻³ M) or vehicle (control group). Locomotor activity was measured using the open field test. CK activity was measured in the brain of rats immediately (1 h) and 7 days after ouabain administration. Our results showed that spontaneous locomotion was increased 1 h after ouabain administration and that hyperlocomotion was also observed 7 days after that. Moreover, CK activity was inhibited immediately after the administration of ouabain in the striatum, hippocampus and prefrontal cortex. Moreover, the enzyme was not affected in the striatum and hippocampus 7 days after ouabain administration. On the other hand, an inhibition in CK activity in the prefrontal cortex was observed. If inhibition of CK also occurs in BD patients, it will be tempting to speculate that the reduction of brain metabolism may be related probably to the pathophysiology of this disease.