Medicine and Health Sciences Commons^™

Transport Of Bmaa Into Neurons And Astrocytes By System XC-, Rebecca Albano, Doug Lobner

Biomedical Sciences Faculty Research and Publications

The study of the mechanism of β-N-methylamino-l-alanine (BMAA) neurotoxicity originally focused on its effects at the N-methyl-d-aspartate (NMDA) receptor. In recent years, it has become clear that its mechanism of action is more complicated. First, there are certain cell types, such as motor neurons and cholinergic neurons, where the dominate mechanism of toxicity is through action at AMPA receptors. Second, even in cortical neurons where the primary mechanism of toxicity appears to be activation of NMDA receptors, there are other mechanisms involved. We found that along with NMDA receptors, activation of mGLuR5 receptors and effects on the …

Pituitary Adenylate Cyclase-Activating Polypeptide Orchestrates Neuronal Regulation Of The Astrocytic Glutamate-Releasing Mechanism System XC−, Linghai Kong, Rebecca Albano, Aric Madayag, Nicholas Raddatz, John R. Mantsch, Sujean Choi, Doug Lobner, David A. Baker

Biomedical Sciences Faculty Research and Publications

Glutamate signaling is achieved by an elaborate network involving neurons and astrocytes. Hence, it is critical to better understand how neurons and astrocytes interact to coordinate the cellular regulation of glutamate signaling. In these studies, we used rat cortical cell cultures to examine whether neurons or releasable neuronal factors were capable of regulating system x_c^-(Sxc), a glutamate-releasing mechanism that is expressed primarily by astrocytes and has been shown to regulate synaptic transmission. We found that astrocytes cultured with neurons or exposed to neuronal-conditioned media displayed significantly higher levels of Sxc activity. Next, we demonstrated that the pituitary …

The Level Of Nmda Receptor In The Membrane Modulates Amyloid-Β Association And Perforation, Christian Peters, Fernando J. Sepúlveda, Eduardo Fernández-Pérez, Robert W. Peoples, Luis G. Aguayo

Biomedical Sciences Faculty Research and Publications

Alzheimer’s disease is a neurodegenerative disorder that affects mostly the elderly. The main histopathological markers are the senile plaques formed by amyloid-β peptide (Aβ) aggregates that can perforate the plasma membrane of cells, increasing the intracellular calcium levels and releasing synaptic vesicles that finally lead to a delayed synaptic failure. Several membrane proteins and lipids interact with Aβ affecting its toxicity in neurons. Here, we focus on NMDA receptors (NMDARs) as proteins that could be modulating the association and neurotoxic perforation induced by Aβ on the plasma membrane. In fact, our results showed that decreasing NMDARs, using enzymatic or siRNA …

Behavioral Assessment Of Acute Inhibition Of System XC - In Rats, Victoria Lutgen, Jon M. Resch, Krista Qualmann, Nicholas J. Raddatz, Cristina Panhans, Ellen M. Olander, Linghai Kong, Sujean Choi, John R. Mantsch, David A. Baker

Biomedical Sciences Faculty Research and Publications

Rationale

Gaps in our understanding of glutamatergic signaling may be key obstacles in accurately modeling complex CNS diseases. System x_c ^- is an example of a poorly understood component of glutamate homeostasis that has the potential to contribute to CNS diseases.

Objectives

This study aims to determine whether system x_c ^- contributes to behaviors used to model features of CNS disease states.

Methods

In situ hybridization was used to map mRNA expression of xCT throughout the brain. Microdialysis in the prefrontal cortex was used to sample extracellular glutamate levels; HPLC was used to measure extracellular glutamate and tissue …

Time Course Of Cocaine-Induced Behavioral And Neurochemical Plasticity, Victoria Lutgen, Linghai Kong, Kristen S. Kau, Aric Madayag, John Mantsch, David A. Baker

Biomedical Sciences Faculty Research and Publications

Factors that result in augmented reinstatement, including increased withdrawal period duration and high levels of cocaine consumption, may provide insight into relapse vulnerability. The neural basis of augmented reinstatement may arise from more pronounced changes in plasticity required for reinstatement and/or the emergence of plasticity expressed only during a specific withdrawal period or under specific intake conditions. In this study, we examined the impact of withdrawal period duration and cocaine intake on the magnitude of cocaine-primed reinstatement and extracellular glutamate in the nucleus accumbens, which has been shown to be required for cocaine-primed reinstatement. Rats were assigned to self-administer under …

Inhibition Of Food Intake By Pacap In The Hypothalamic Ventromedial Nuclei Is Mediated By Nmda Receptors, Jon M. Resch, Brian Maunze, Kailynn A. Phillips, Sujean Choi

Biomedical Sciences Faculty Research and Publications

Central injections of pituitary adenylate cyclase-activating polypeptide (PACAP) into the ventromedial nuclei (VMN) of the hypothalamus produce hypophagia that is dependent upon the PAC1 receptor; however, the signaling downstream of this receptor in the VMN is unknown. Though PACAP signaling has many targets, this neuropeptide has been shown to influence glutamate signaling in several brain regions through mechanisms involving NMDA receptor potentiation via activation of the Src family of protein tyrosine kinases. With this in mind, we examined the Src-NMDA receptor signaling pathway as a target for PACAP signaling in the VMN that may mediate its effects on feeding behavior. …

Fgf-2 Induces Neuronal Death Through Upregulation Of System Xc-, Xiaoqian Liu, Rebecca Albano, Doug Lobner

Biomedical Sciences Faculty Research and Publications

The cystine/glutamate antiporter (system xc-) transports cystine into cell in exchange for glutamate. Fibroblast growth factor-2 (FGF-2) upregulates system xc- selectively on astrocytes, which leads to increased cystine uptake, the substrate for glutathione production, and increased glutamate release. While increased intracellular glutathione can limit oxidative stress, the increased glutamate release can potentially lead to excitotoxicity to neurons. To test this hypothesis, mixed neuronal and glial cortical cultures were treated with FGF-2. Treatment with FGF-2 for 48 h caused a significant neuronal death in these cultures. Cell death was not observed in neuronal-enriched cultures, or astrocyte-enriched …

Reduction In Phencyclidine Induced Sensorimotor Gating Deficits In The Rat Following Increased System Xc − Activity In The Medial Prefrontal Cortex, Victoria Lutgen, Krista Qualmann, Jon M. Resch, Linghai Kong, Sujean Choi, David A. Baker

Biomedical Sciences Faculty Research and Publications

Rationale: Aspects of schizophrenia, including deficits in sensorimotor gating, have been linked to glutamate dysfunction and/or oxidative stress in the prefrontal cortex. System x_c ⁻, a cystine–glutamate antiporter, is a poorly understood mechanism that contributes to both cellular antioxidant capacity and glutamate homeostasis.

Objectives: Our goal was to determine whether increased system x_c ⁻ activity within the prefrontal cortex would normalize a rodent measure of sensorimotor gating.

Methods: In situ hybridization was used to map messenger RNA (mRNA) expression of xCT, the active subunit of system x_c ⁻, in the prefrontal cortex. Prepulse inhibition was …

Blunted Cystine–Glutamate Antiporter Function In The Nucleus Accumbens Promotes Cocaine-Induced Drug Seeking, Kristen S. Kau, Aric Madayag, John R. Mantsch, Mark D. Grier, Omer Abdulhameed, David A. Baker

Biomedical Sciences Faculty Research and Publications

Repeated cocaine alters glutamate neurotransmission, in part, by reducing cystine–glutamate exchange via system x_c−, which maintains glutamate levels and receptor stimulation in the extrasynaptic compartment. In the present study, we undertook two approaches to determine the significance of plasticity involving system x_c−. First, we examined whether the cysteine prodrug N-acetylcysteine attenuates cocaine-primed reinstatement by targeting system x_c−. Rats were trained to self-administer cocaine (1 mg/kg/200 μl, i.v.) under extended access conditions (6 h/day). After extinction training, cocaine (10 mg/kg, i.p.) primed reinstatement was assessed in rats pretreated with N-acetylcysteine (0–60 mg/kg, i.p.) in the …