Effects of syringic acid on chronic MPTP/probenecid induced motor dysfunction, dopaminergic markers expression and neuroinflammation in C57BL/6 mice

Syringic acid (SA) is a naturally occurring O-methylated trihydroxybenzoic acid present in wine and released as a breakdown product of malvidin, a primary plant pigment (an anthocyanidin). In this study, the neuroprotective efficacy of syringic acid (SA) on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probencid (MPTP/p) induced mouse model of PD was investigated. The C57BL/6 mice were given 10 doses of MPTP/p for five consecutive weeks with 3.5 day interval. Administration of MPTP/p led to reduced motor coordination, neurochemicals and tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter-2 (VMAT2) expression. In addition, increased oxidative stress markers and the expression of inflammatory markers, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and cyclooxygenase-2 (COX-2). Pre-oral treatment with SA (20 mg/kg) was found to improve the MPTP/p-induced impaired motor functions by restoring the catecholamine content and antioxidant enzymes level. In addition, it ameliorated the expressions of TH, DAT and VMAT2 and also significantly attenuated MPTP/p-induced increased inflammatory markers expressions. These results partially explain the pharmacological efficacy of SA as a potential therapeutic agent for the treatment of MPTP/p-induced mice model of PD, together with its neuroprotective effect and reduce the progression of PD.