The hypnotic bromovalerylurea ameliorates 6-hydroxydopamine-induced dopaminergic neuron loss while suppressing expression of interferon regulatory factors by microglia

• The hypnotic bromovalerylurea (BU) suppressed LPS-induced microglial activation.
• Oral BU prevented neurodegeneration in the rat model of 6-OHDA-induced Parkinsonism.
• BU suppressed proinflammatory factor expression in the Parkinsonian rat brain.
• BU suppressed interferon regulatory factors 1 and 8 expression by microglia.

The low molecular weight organic compound bromovalerylurea (BU) has long been used as a hypnotic/sedative. In the present study, we found that BU suppressed mRNA expression of proinflammatory factors and nitric oxide release in lipopolysaccharide (LPS)-treated rat primary microglial cell cultures. BU prevented neuronal degeneration in LPS-treated neuron-microglia cocultures. The anti-inflammatory effects of BU were as strong as those of a synthetic glucocorticoid, dexamethasone. A rat hemi-Parkinsonian model was prepared by injecting 6-hydroxydopamine into the right striatum. BU was orally administered to these rats for 7 days, which ameliorated the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and alleviated motor deficits. BU suppressed the expression of mRNAs for interferon regulatory factors (IRFs) 1, 7 and 8 in the right (lesioned) ventral midbrain as well as those for proinflammatory mediators. BU increased mRNA expression of various neuroprotective factors, including platelet-derived growth factor and hepatocyte growth factor, but it did not increase expression of alternative activation (M2) markers. In microglial culture, BU suppressed the LPS-induced increase in expression of IRFs 1 and 8, and it reduced LPS-induced phosphorylation of JAK1 and STATs 1 and 3. Knockdown of IRFs 1 and 8 suppressed LPS-induced NO release by microglial cells. These results suggest that suppression of microglial IRF expression by BU prevents neuronal cell death in the injured brain region, where microglial activation occurs. Because many Parkinsonian patients suffer from sleep disorders, BU administration before sleep may effectively ameliorate neurological symptoms and alleviate sleep dysfunction.