Vitamin D₃ Receptor Activation Rescued Corticostriatal Neural Activity and Improved Motor Function in –D₂R Tardive Dyskinesia Mice Model

Abstract

Haloperidol-induced dyskinesia has been linked to a reduction in dopamine activity characterized by the inhibition of dopamine receptive sites on D 2 -receptor (D 2 R). As a result of D 2 R inhibition, calcium-linked neural activity is affected and seen as a decline in mo-tor-cognitive function after prolonged haloperidol use in the treatment of psychotic disorders. In this study, we have elucidated the relationship between haloperidol-induced tardive dyskinesia and the neural activity in motor cortex (M1), basal nucleus (CPu), prefrontal cortex (PFC) and hippocampus (CA1). Also, we explored the role of Vitamin D3 receptor (VD 3 R) activation as a therapeutic target in improving motor-cognitive functions in dyskinetic mice. Dyskinesia was induced in adult BALB/c mice after 28 days of haloperidol treatment (10 mg/Kg; intraperitoneal). We established the presence of abnormal involuntary movements (AIMs) in the haloperidol treated mice (-D 2 ) through assessment of the threshold and amplitude of abnormal involuntary movements (AIMs) for the Limbs (Li) and Orolingual (Ol) area (Li and Ol AIMs). As a confirmatory test, the dyskinetic mice (-D 2 ) showed high global AIMs score when compared with the VD3RA intervention group (-D 2 /+VDR) for Li and Ol AIMs. Furthermore, in the behavioral tests, the dyskinetic mice exhibited a decrease in latency of fall (LOF; Rotarod-P < 0.05), climbing attempts (Cylinder test; P < 0.05) and latency of Turning (Parallel bar test; LOT-P < 0.05) when compared with the control. The reduced motor function in dyskinetic mice was associated with a decline in CPu-CA1 burst frequencies and an increase in M1-PFC cortical activity. However, after VD3RA intervention (-D 2 /+VDR), 100 mg/Kg for 7 days, CPu-CA1 burst activity was restored leading to a decrease in abnormal movement, and an increase in motor function. Ultimately, we deduced that VD 3 RA activation reduced the threshold of abnormal movement in haloperidol induced dyskinesia.