HDAC inhibitors reverse mania-like behavior and modulate epigenetic regulatory enzymes in an animal model of mania induced by Ouabain.

Background: The etiology of bipolar disorder (BD) is multifactorial, involving both environmental and genetic factors. Current pharmacological treatment is associated with several side effects, which are the main reason patients discontinue treatment. Epigenetic alterations have been studied for their role in the pathophysiology of BD, as they bridge the gap between gene and environment.

Objective: Evaluate the effects of histone deacetylase inhibitors on behavior and epigenetic enzymes activity in a rat model of mania induced by ouabain.

Methods: Adult male rats were subjected to a single intracerebroventricular injection of ouabain (10 M) followed by 7 days of valproate (200 mg/kg) or sodium butyrate (600 mg/kg) administration. Locomotor and exploratory activities were evaluated in the open-field test. Histone deacetylase, DNA methyltransferase, and histone acetyltransferase activity were assessed in the frontal cortex, hippocampus, and striatum.

Results: Ouabain induced hyperactivity in rats, which was reversed by valproate and sodium butyrate treatment. Ouabain did not alter the activity of any of the enzymes evaluated. However, valproate and sodium butyrate decreased the activity of histone deacetylase and DNA methyltransferase. Moreover, there was a positive correlation between these two enzymes.

Conclusion: These results suggest that targeting epigenetic mechanisms may play an important role in mania-like behavior management.