The Role of E3 Ligase Parkin in Trafficking of Monoamine Storage Vesicles in Rat Model of Methamphetamine Neurotoxicity

Methamphetamine (METH), a psychostimulant, is a widely used drug of abuse. METH is toxic to dopaminergic (DAergic) and serotonergic (5-HT) nerve terminals in the striatum when administered at high doses. METH releases Dopamine (DA) from vesicular monoamine transporter 2 (VMAT2) containing synaptic vesicles and induces oxidative stress by auto-oxidation of DA. The VMAT2 plays a neurprotective role by sequestering cytoplasmic DA into vesicles for storage and protection from auto-oxidation. It has previously been shown that METH toxicity is associated with impaired VMAT2 trafficking and oxidative damage to the E3 ligase parkin. CDCrel1, a protein found to inhibit exocytosis, is regulated by parkin. We hypothesized that METH-mediated decrease in parkin causes accumulation of the parkin substrate CDCrel1, which entraps VMAT2 vesicles at the plasma membrane, preventing their recycling to the cytosol. We observed inability of the VMAT2 vesicles to mobilize to the cytosol due to a possible CDCrel-1 mediated entrapment following METH. Our findings suggest that CDCrel1 could partially entrap VMAT2 vesicles at the membrane, impairing their normal 151 recycling to the cytosol. We executed a parkin overexpression study to evaluate whether parkin protects against the METH-induced dysfunction of VMAT2 trafficking. We found that parkin does not reverse the impaired trafficking of VMAT2 caused by binge METH.