The goal of this research is to help bridge the gap between methamphetamine (MA) neurotoxicity and effective therapeutic intervention. Using a D1 dopamine (DA) receptor-expressing neuroepithelioma cell line (SK-N-MC) that lacks DA transporters, we have developed an in vitro system that models post-synaptic neurons directly targeted by MA toxicity. By utilizing this model we will study novel molecular mechanisms involved in MA-induced neurotoxicity, in particular the contribution of heme oxygenase-1 (HO-1), reactive nitrogen species (RNS) and manganese superoxide dismutase (MnSOD). We hypothesize that DA stimulation, via a process mediated by HO-1, leads to generation of RNS and mitochondrial-mediated apoptosis through nitration of MnSOD. Our hypothesis will be tested in the following three specific aims: 1) Test whether HO-1 expression is involved in RNS production, 2) Test whether inhibition of HO-1 attenuates DA-induced mitochondrial-mediated apoptosis, and 3) Determine if MnSOD is nitrated and if treatment with a general antioxidant or mimetic attenuates DA-induced nitration and/or mitochondrial-mediated apoptosis. We will investigate ways to decrease MA neurotoxicity through studies aimed at manipulation of HO-1 and MnSOD activity in order to limit RNS production and subsequent apoptosis. This will be done using innovative methods such as siRNA-mediated knock-down of HO-1 expression, or increased MnSOD catalytic activity via pharmacological mimetics as well as utilizing compounds that have previously demonstrated clinical relevance in other disease states, such as Sn (IV) mesoporphyrin IX. These findings will enable the development of new therapeutic approaches that, when given as a pre-treatment, will minimize further neurological damage to those struggling with the disease of MA addiction.
Methamphetamine is a particularly devastating drug as its abuse has been shown to cause localized brain damage equivalent to that seen in patients with early dementia and greater than that seen in those with schizophrenia. In order to develop effective therapeutics to combat the brain damage seen in methamphetamine addicts, it is essential to first understand how the brain damage occurs. This research proposal is aimed at determining, on a molecular level, what happens inside brain cells to cause them to die after being exposed to methamphetamine. In light of this new-found information, the scientific community will be closer to developing new and effective treatments for methamphetamine toxicity.
