A study of motor activity and catecholamine levels in different brain regions following Japanese encephalitis virus infection in rats

Japanese encephalitis (JE) is associated with a variety of movement disorders including transient form of pakinsonian features, dystonia and miscellaneous movement disorders. The neurotransmitters have important role in movement disorders. However their role in different brain regions in relation to behavioral activities in animal model of JE is not understood. The present study was aimed to investigate the behavioral parameters, the levels of catecholamine in brain regions-thalamus, midbrain, corpus striatum and frontal cortex on 0, 10 and 20 days post inoculation (dpi) with histopathological observations. Twelve day old Wistar strain rats were inoculated intracerebrally with a dose of 3 × 10⁶ pfu of JE virus. Spontaneous locomotor activity (SLA) and grip strength were monitored. The levels of catecholamine were estimated using HPLC-ECD and histopathological changes were observed using haematoxylin and eosine staining. A significant decrease in SLA and grip strength was observed in JEV infected rats as compared to controls on 10 and 20 dpi. The levels of norepinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and serotonin were significantly decreased in all the brain regions studied with respect to controls. We did not find significant recovery in catecholamine levels and locomotor activities up to 20 dpi and any significant correlation between behavioral changes and neurotransmitter levels. However histopathological studies revealed mild reduction in degree of damage on 20 dpi. The present study demonstrates the involvement of different brain regions in altered locomotor activity which may be associated with reduction in catecholamine levels in rat model of JE.