Curcumin protects nigrostriatal dopaminergic axons and increases BDNF immunoreactivity in the 6-OHDA-lesioned striatum of mice

Abstract

Background: Brain-derived neurotrophic factor (BDNF) exerts neuroprotection upon the nigrostriatal dopaminergic (DA) neurons and their projections in animal models of Parkinson’s disease (PD). Recent data indicate neuroprotective effects of curcumin in animal models of PD via anti-inflammatory and anti-oxidant actions. However, there are no studies investigating the effects of curcumin on BDNF levels in the striatum of the 6-hydroxydopamine (6-OHDA) mouse model of PD. Objective: The present study investigated the effects of curcumin on the extent of nigrostriatal DA innervation and BDNF levels in the striatum of 6-OHDA-lesioned mice. Materials and Methods: 6-OHDA was unilaterally injected into the right striatum of ICR male mice. Curcumin (200 mg/kg) or vehicle (dimethyl sulfoxide) was intraperitoneally administered daily for 7 days starting instantaneously after 6-OHDA injection. Seven days after 6-OHDA insult, mice were euthanized and striatal sections were collected, immunohistochemically stained, and quantitated for tyrosine hydroxylase (TH, a marker for DA neurons) and BDNF immunoreactivity. Results: 6-OHDA injection induced a significant loss of TH-immunoreactive (-IR) axons and increased BDNF expression in the 6-OHDA-lesioned striatum. Curcumin diminished loss of TH-IR fibers and additionally promoted increases in BDNF levels in the 6-OHDA-lesioned striatum. Conclusion: One possible mechanism by which curcumin protects nigrostriatal DA axons against 6-OHDA is through upregulation of striatal BDNF. © JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND| 2019.