Neuroscience
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/30817
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Browsing Neuroscience by Author "Forster, Michael"
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Item Methionine Synthase: A target for novel small molecules to inhibit cocaine and methamphetamine induced neuronal death(2022) Young, Olivia; Funk, Arlene; Deb, Biddut; Amankwa, Charles E.; Chintagunta, Anila; Gondi, Sudershan; Forster, Michael; Shetty, Ritu; Acharya, SuchismitaPurpose: Oxidative stress-induced cell death is involved in the pathology of psychostimulant addiction neuropathies and ischemic stroke. These conditions potentially cause neuronal and functional changes via different mechanisms - epigenetic alterations (DNA hypomethylation) and reactive oxygen species (ROS) accumulation. Current medications for the treatment of psychostimulants (e.g., cocaine and methamphetamine) induced addiction neuropathies are largely ineffective due to the high rate of relapse and marginal alterations of dependency to these diseases. To circumvent this, our laboratory has synthesized novel hybrid antioxidant small molecules: SA-30 and SA-31, with predictive neuroprotective and broad-spectrum reactive oxygen species (ROS) scavenging abilities in mouse hippocampal HT22 neural cells. Our objective here was to test if the compounds increase cell proliferation, superoxide dismutase (SOD) enzyme, as well as methionine synthase (MS) enzyme, a key enzyme largely responsible for DNA methylation, neuronal growth, and survival using human neuroblastoma cells (SH-SY5Y) expressing dopaminergic neurons. Methods: The synthesis and structure characterization of compounds SA-30 and SA-31 were previously synthesized in Acharya lab using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. Human neuroblastoma cells SH-SY5Y expressing dopaminergic neurons were purchased (ATCC), cultured, and treated with different concentrations of cocaine hydrochloride or methamphetamine for 8, 24, and 48h for determining EC50 using MTT assay. In the next experiment, either cocaine hydrochloride (1.5mM) or Methamphetamine (METH, 3.5 mM) was added followed by co-treatment with compounds SA-30 and SA-31 and 4-hydroxy tempol (all at 100µM) for 24 hours. Cell viability was assessed using MTT assay. The level of intracellular MS and SOD enzymes was assessed using ELISA. Results: In SHSY5Y cells, the EC50 of cocaine was 1.5 mM, and for METH was 3.5 mM after 24h of treatment. Both compounds SA-30 and SA-31 were not cytotoxic at varying concentrations (0.01, 0.1, 1, 10, 100µM) and rescued cells from both cocaine and METH-induced oxidative stress/cell death at 100µM concentrations. SA-31 at 100µM significantly increased (~1.5 fold) intracellular MS as compared to control. There was a decrease in MS level after METH treatment and treatment with SA-30 and SA-31 increased the level. SOD levels were significantly higher (~3 fold) in METH+SA-31 treated groups than only METH groups. Conclusion: Both novel hybrid small molecules SA-30 and SA-31 are neuroprotective in SH-SY5Y cells from psychostimulants cocaine and METH-induced oxidative stress/neural cell death. Increasing MS and SOD enzyme activities is one of the mechanisms by which neuroprotection was attained. Future studies will address the potential of both SA-30 and SA-31 to progress further in pre-clinical drug development, with a future application for the treatment of substance abuse disorder.Item The effects of previous exposure to chronic methamphetamine on drug-seeking behavior and neurodegeneration in male and female mice(2022) Davis, Delaney; Metzger, Daniel; Vann, Philip; Wong, Jessica; Shetty, Ritu; Forster, Michael; Sumien, NathaliePurpose: Recreational and medical use of stimulants among young adults have gained popularity in the United States over the last decade, with amphetamine compounds becoming the second most common illicit drug used in college students. Although amphetamine stimulants have proven to be safe and efficacious in children and adults with Attention Deficit and Hyperactivity Disorder (ADHD) when used as prescribed, these drugs can have significant adverse side effects such as an increased potential of recreational abuse liability, dependence, and neurotoxicity. There are known sex differences in drug abuse, in which women have lower rates of illicit drug use, but use more of the drug, reach dependence faster and have more adverse effects. We hypothesize that females may be more vulnerable to the reinforcing effects of METH as well as METH-induced neurotoxicity and dopaminergic dysregulation. Our study investigated the effects of early chronic exposure to the prototypical stimulant, methamphetamine (METH), at a dose designed to emulate human therapeutic dosing, on abuse potential and biochemical markers of dopaminergic function and neurodegeneration in male and female mice. Methods: Groups of 4-month-old male and female C57BL/6J mice were administered non-contingent intraperitoneal injections of either saline or METH (1.4 mg/kg) twice a day for 4 weeks. METH (0.5 mg/kg)-induced conditioned place preference (CPP) was tested in mice to determine the reinforcing effects of previous METH exposure. Mice were randomly assigned to either: Experiment I (short-term) in which male and female mice underwent CPP 13 days after injection cessation or Experiment II (long-term) in which female mice underwent CPP 5 months after injection cessation. Following behavioral testing, the animals were euthanized and striatum and midbrain were collected for biochemical testing of dopaminergic function and neurodegeneration. Results: In Experiment I, chronic METH exposure induced drug preference for subsequent doses of METH especially in males, and downregulated dopaminergic markers in males and induced apoptosis in females. In Experiment II, when CPP was performed 5 months after injection cessation, females with prior exposure to METH did not exhibit drug preference to subsequent doses of METH and there were no effects on markers of neurodegeneration or dopaminergic function. Conclusion: Previous exposure to METH induced a heightened sensitivity to subsequent doses of METH especially in males. While the effect in females was smaller, it disappeared in the long-term suggesting that this heightened sensitivity does not last over time. The increase in sensitivity was supported by alterations in the dopaminergic system in males. These outcomes suggest sex differences in response to prior METH exposure, and that these effects may not be long-lasting.