Publications -- Nathalie Sumien

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This collection is limited to articles published under the terms of a creative commons license or other open access publishing agreement since 2016. It is not intended as a complete list of the author's works.

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    Locomotor and discriminative stimulus effects of three benzofuran compounds in comparison to abused psychostimulants
    (Elsevier B.V., 2023-08-21) Hill, Rebecca D.; Shetty, Ritu A.; Sumien, Nathalie; Forster, Michael J.; Gatch, Michael B.
    AIMS: Benzofurans are used recreationally, due their ability to cause psychostimulant and/or entactogenic effects, but unfortunately produce substantial adverse effects, including death. Three benzofurans 5-(2-aminopropyl)-2,3-dihydrobenzofuran (5-APDB), 5-(2-aminopropyl)-2,3-dihydrobenzofuran (5-MAPB) and 6-(2-aminopropyl) benzofuran (6-APB) were tested to determine their behavioral effects in comparison with 2,3-methylenedioxymethamphetamine (MDMA), cocaine, and methamphetamine. METHODS: Locomotor activity was tested in groups of 8 male Swiss-Webster mice in an open-field task to screen for locomotor stimulant or depressant effects and to identify behaviorally active doses and times of peak effect. Discriminative stimulus effects were tested in groups of 6 male Sprague-Dawley rats trained to discriminate MDMA (1.5 mg/kg), cocaine (10 mg/kg), or methamphetamine (1 mg/kg) from saline using a FR 10 for food in a two-lever operant task. RESULTS: In the locomotor activity test, MDMA (ED(50) = 8.34 mg/kg) produced peak stimulant effects 60 to 80 min following injection. 5-MAPB (ED(50) = 0.92 mg/kg) produced modest stimulant effects 50 to 80 min after injection, whereas 6-APB (ED(50) = 1.96 mg/kg) produced a robust stimulant effect 20 to 50 min after injection. 5-APDB produced an early depressant phase (ED(50) = 3.38 mg/kg) followed by a modest stimulant phase (ED(50) = 2.57 mg/kg) 20 to 50 min after injection. In the drug discrimination tests, 5-APDB (ED(50) = 1.02 mg/kg), 5-MAPB (ED(50) = 1.00 mg/kg) and 6-APB (ED(50) = 0.32 mg/kg) fully substituted in MDMA-trained rats, whereas only 5-MAPB fully substituted for cocaine, and no compounds fully substituted for methamphetamine. CONCLUSIONS: The synthetic benzofuran compound 5-APDB and 5-MAPB produced weak locomotor effects, whereas 6-APB produced robust locomotor stimulant effects. All compounds were more potent than MDMA. All three compounds fully substituted in MDMA-trained rats suggesting similar subjective effects. Taken together, these results suggest that these benzofuran compounds may have abuse liability as substitutes for MDMA.
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    Novel pharmacotherapy: NNI-362, an allosteric p70S6 kinase stimulator, reverses cognitive and neural regenerative deficits in models of aging and disease
    (BioMed Central Ltd., 2021-01-13) Sumien, Nathalie; Wells, Matthew S.; Sidhu, Akram; Wong, Jessica M.; Forster, Michael J.; Zheng, Qiao-Xi; Kelleher-Andersson, Judith A.
    Aging is known to slow the neurogenic capacity of the hippocampus, one of only two mammalian adult neurogenic niches. The reduction of adult-born neurons with age may initiate cognitive decline progression which is exacerbated in chronic neurodegenerative disorders, e.g., Alzheimer's disease (AD). With physiologic neurogenesis diminished, but still viable in aging, non-invasive therapeutic modulation of this neuron regeneration process remains possible. The discovery of truly novel neuron regenerative therapies could be identified through phenotypic screening of small molecules that promote adult-born neurons from human neural progenitor cells (hNPCs). By identifying neuron-generating therapeutics and potentially novel mechanism of actions, therapeutic benefit could be confirmed through in vivo proof-of-concept studies. The key aging and longevity mTOR/p70S6 kinase axis, a commonly targeted pathway, is substrate for potential selective kinase modulators to promote new hippocampal neurons from NPCs. The highly regulated downstream substrate of mTOR, p70S6 kinase, directly controls pleiotropic cellular activities, including translation and cell growth. Stimulating this kinase, selectively in an adult neurogenic niche, should promote NPC proliferation, and cell growth and survival in the hippocampus. Studies of kinase profiling and immunocytochemistry of human progenitor neurogenesis suggest that the novel small molecule NNI-362 stimulates p70S6 kinase phosphorylation, which, in turn, promotes proliferation and differentiation of NPCs to neurons. NNI-362 promoted the associative reversal of age- and disease-related cognitive deficits in aged mice and Down syndrome-modeled mice. This oral, allosteric modulator may ultimately be beneficial for age-related neurodegenerative disorders involving hippocampal-dependent cognitive impairment, specifically AD, by promoting endogenous hippocampal regeneration.
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    Long-term HIV-1 Tat Expression in the Brain Led to Neurobehavioral, Pathological, and Epigenetic Changes Reminiscent of Accelerated Aging
    (International Society on Aging and Disease, 2020-02-01) Zhao, Xiaojie; Fan, Yan; Vann, Philip H.; Wong, Jessica M.; Sumien, Nathalie; He, Johnny J.
    HIV infects the central nervous system and causes HIV/neuroAIDS, which is predominantly manifested in the form of mild cognitive and motor disorder in the era of combination antiretroviral therapy. HIV Tat protein is known to be a major pathogenic factor for HIV/neuroAIDS through a myriad of direct and indirect mechanisms. However, most, if not all of studies involve short-time exposure of recombinant Tat protein in vitro or short-term Tat expression in vivo. In this study, we took advantage of the doxycycline-inducible brain-specific HIV-1 Tat transgenic mouse model, fed the animals for 12 months, and assessed behavioral, pathological, and epigenetic changes in these mice. Long-term Tat expression led to poorer short-and long-term memory, lower locomotor activity and impaired coordination and balance ability, increased astrocyte activation and compromised neuronal integrity, and decreased global genomic DNA methylation. There were sex- and brain region-dependent differences in behaviors, pathologies, and epigenetic changes resulting from long-term Tat expression. All these changes are reminiscent of accelerated aging, raising the possibility that HIV Tat contributes, at least in part, to HIV infection-associated accelerated aging in HIV-infected individuals. These findings also suggest another utility of this model for HIV infection-associated accelerated aging studies.
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    Pancreatic mitochondrial complex I exhibits aberrant hyperactivity in diabetes
    (Elsevier Inc., 2017-07-19) Wu, Jinzi; Luo, Xiaoting; Thangthaeng, Nopporn; Sumien, Nathalie; Chen, Zhenglan; Rutledge, Margaret A.; Jing, Siqun; Forster, Michael J.; Yan, Liang-Jun
    It is well established that NADH/NAD(+) redox balance is heavily perturbed in diabetes, and the NADH/NAD(+) redox imbalance is a major source of oxidative stress in diabetic tissues. In mitochondria, complex I is the only site for NADH oxidation and NAD(+) regeneration and is also a major site for production of mitochondrial reactive oxygen species (ROS). Yet how complex I responds to the NADH/NAD(+) redox imbalance and any potential consequences of such response in diabetic pancreas have not been investigated. We report here that pancreatic mitochondrial complex I showed aberrant hyperactivity in either type 1 or type 2 diabetes. Further studies focusing on streptozotocin (STZ)-induced diabetes indicate that complex I hyperactivity could be attenuated by metformin. Moreover, complex I hyperactivity was accompanied by increased activities of complexes II to IV, but not complex V, suggesting that overflow of NADH via complex I in diabetes could be diverted to ROS production. Indeed in diabetic pancreas, ROS production and oxidative stress increased and mitochondrial ATP production decreased, which can be attributed to impaired pancreatic mitochondrial membrane potential that is responsible for increased cell death. Additionally, cellular defense systems such as glucose 6-phosphate dehydrogenase, sirtuin 3, and NQO1 were found to be compromised in diabetic pancreas. Our findings point to the direction that complex I aberrant hyperactivity in pancreas could be a major source of oxidative stress and beta cell failure in diabetes. Therefore, inhibiting pancreatic complex I hyperactivity and attenuating its ROS production by various means in diabetes might serve as a promising approach for anti-diabetic therapies.
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    Gait Analyses in Mice: Effects of Age and Glutathione Deficiency
    (International Society on Aging and Disease, 2018-08-01) Mock, J. Thomas; Knight, Sherilynn G.; Vann, Philip H.; Wong, Jessica M.; Davis, Delaney L.; Forster, Michael J.; Sumien, Nathalie
    Minor changes (~0.1 m/s) in human gait speed are predictive of various measures of decline and can be used to identify at-risk individuals prior to further decline. These associations are possible due to an abundance of human clinical research. However, age-related gait changes are not well defined in rodents, even though rodents are used as the primary pre-clinical model for many disease states as well as aging research. Our study investigated the usefulness of a novel automated system, the CatWalk XT, to measure age-related differences in gait. Furthermore, age-related functional declines have been associated with decreases in the reduced to oxidized glutathione ratio leading to a pro-oxidizing cellular shift. Therefore the secondary aim of this study was to determine whether chronic glutathione deficiency led to exacerbated age-associated impairments. Groups of male and female wild-type (gclm(+/+)) and knock-out (gclm(-/-)) mice aged 4, 10 and 17 months were tested on the CatWalk and gait measurements recorded. Similar age-related declines in all measures of gait were observed in both males and females, and chronic glutathione depletion was associated with some delays in age-related declines, which were further exacerbated. In conclusion, the CatWalk is a useful tool to assess gait changes with age, and further studies will be required to identify the potential compensating mechanisms underlying the effects observed with the chronic glutathione depletion.
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    Astrocyte HIV-1 Tat Differentially Modulates Behavior and Brain MMP/TIMP Balance During Short and Prolonged Induction in Transgenic Mice
    (Frontiers Media S.A., 2020-12-15) Joshi, Chaitanya R.; Stacy, Satomi; Sumien, Nathalie; Ghorpade, Anuja; Borgmann, Kathleen
    Despite effective antiretroviral therapy (ART), mild forms of HIV-associated neurocognitive disorders (HAND) continue to afflict approximately half of all people living with HIV (PLWH). As PLWH age, HIV-associated inflammation perturbs the balance between brain matrix metalloproteinases (MMPs) and their tissue inhibitors of metalloproteinases (TIMPs), likely contributing to neuropathogenesis. The MMP/TIMP balance is associated with cognition, learning, and memory, with TIMPs eliciting neuroprotective effects. Dysregulation of the MMP/TIMP balance was evident in the brains of PLWH where levels of TIMP-1, the inducible family member, were significantly lower than non-infected controls, and MMPs were elevated. Here, we evaluated the MMP/TIMP levels in the doxycycline (DOX)-induced glial fibrillary acidic protein promoter-driven HIV-1 transactivator of transcription (Tat) transgenic mouse model. The HIV-1 protein Tat is constitutively expressed by most infected cells, even during ART suppression of viral replication. Many studies have demonstrated indirect and direct mechanisms of short-term Tat-associated neurodegeneration, including gliosis, blood-brain barrier disruption, elevated inflammatory mediators and neurotoxicity. However, the effects of acute vs. prolonged exposure on Tat-induced dysregulation remain to be seen. This is especially relevant for TIMP-1 as expression was previously shown to be differentially regulated in human astrocytes during acute vs. chronic inflammation. In this context, acute Tat expression was induced with DOX intraperitoneal injections over 3 weeks, while DOX-containing diet was used to achieve long-term Tat expression over 6 months. First, a series of behavior tests evaluating arousal, ambulation, anxiety, and cognition was performed to examine impairments analogous to those observed in HAND. Next, gene expression of components of the MMP/TIMP axis and known HAND-relevant inflammatory mediators were assessed. Altered anxiety-like, motor and/or cognitive behaviors were observed in Tat-induced (iTat) mice. Gene expression of MMPs and TIMPs was altered depending on the duration of Tat expression, which was independent of the HIV-associated neuroinflammation typically implicated in MMP/TIMP regulation. Collectively, we infer that HIV-1 Tat-mediated dysregulation of MMP/TIMP axis and behavioral changes are dependent on duration of exposure. Further, prolonged Tat expression demonstrates a phenotype comparable to asymptomatic to mild HAND manifestation in patients.
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    Evaluation of Substituted N-Phenylpiperazine Analogs as D3 vs. D2 Dopamine Receptor Subtype Selective Ligands
    (MDPI, 2021-05-26) Lee, Boeun; Taylor, Michelle; Griffin, Suzy A.; McInnis, Tamara; Sumien, Nathalie; Mach, Robert H.; Luedtke, Robert R.
    N-phenylpiperazine analogs can bind selectively to the D3 versus the D2 dopamine receptor subtype despite the fact that these two D2-like dopamine receptor subtypes exhibit substantial amino acid sequence homology. The binding for a number of these receptor subtype selective compounds was found to be consistent with their ability to bind at the D3 dopamine receptor subtype in a bitopic manner. In this study, a series of the 3-thiophenephenyl and 4-thiazolylphenyl fluoride substituted N-phenylpiperazine analogs were evaluated. Compound 6a was found to bind at the human D3 receptor with nanomolar affinity with substantial D3 vs. D2 binding selectivity (approximately 500-fold). Compound 6a was also tested for activity in two in-vivo assays: (1) a hallucinogenic-dependent head twitch response inhibition assay using DBA/2J mice and (2) an L-dopa-dependent abnormal involuntary movement (AIM) inhibition assay using unilateral 6-hydroxydopamine lesioned (hemiparkinsonian) rats. Compound 6a was found to be active in both assays. This compound could lead to a better understanding of how a bitopic D3 dopamine receptor selective ligand might lead to the development of pharmacotherapeutics for the treatment of levodopa-induced dyskinesia (LID) in patients with Parkinson's disease.
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    ApoE Genotype-Dependent Response to Antioxidant and Exercise Interventions on Brain Function
    (MDPI, 2020-06-25) Chaudhari, Kiran; Wong, Jessica M.; Vann, Philip H.; Como, Tori; O'Bryant, Sid E.; Sumien, Nathalie
    This study determined whether antioxidant supplementation is a viable complement to exercise regimens in improving cognitive and motor performance in a mouse model of Alzheimer's disease risk. Starting at 12 months of age, separate groups of male and female mice expressing human Apolipoprotein E3 (GFAP-ApoE3) or E4 (GFAP-ApoE4) were fed either a control diet or a diet supplemented with vitamins E and C. The mice were further separated into a sedentary group or a group that followed a daily exercise regimen. After 8 weeks on the treatments, the mice were administered a battery of functional tests including tests to measure reflex and motor, cognitive, and affective function while remaining on their treatment. Subsequently, plasma inflammatory markers and catalase activity in brain regions were measured. Overall, the GFAP-ApoE4 mice exhibited poorer motor function and spatial learning and memory. The treatments improved balance, learning, and cognitive flexibility in the GFAP-ApoE3 mice and overall the GFAP-ApoE4 mice were not responsive. The addition of antioxidants to supplement a training regimen only provided further benefits to the active avoidance task, and there was no antagonistic interaction between the two interventions. These outcomes are indicative that there is a window of opportunity for treatment and that genotype plays an important role in response to interventions.