Department of Anesthesiology (UMKC)
https://hdl.handle.net/10355/8385
The Department of Anesthesiology is a department in the School of Medicine.2024-03-28T18:08:26ZAmphetamine Alters Acid-Sensing Ion Channel Expression in the Rat Striatum
https://hdl.handle.net/10355/6354
Amphetamine Alters Acid-Sensing Ion Channel Expression in the Rat Striatum
Suman, A.; Mao, Li-Min; Fibuch, Eugene; Wang, John Q.
Introduction: The acid-sensing ion channel (ASIC) is specifically activated by a drop in the extracellular pH level. These channels are widely expressed in mammalian brains and actively modulate synaptic transmission and a variety of neuronal activities. In the striatum, two ASIC subtypes (ASIC1 and ASIC2) are densely expressed. Given the fact that the striatum is a central site for processing biological actions of drugs of abuse, expression of abundant ASICs in this structure implies a potential involvement of the channel in drug effects. In this study, we examined the expression of ASIC1 and ASIC2 in the rat striatum in response to chronic exposure to the psychostimulant amphetamine in vivo.
Methods: Following IACUC approval, adult male Wistar rats (2 groups, n = 6 per group) received intraperitoneal injections of saline or amphetamine (once daily for 7 days, 1.25 mg/kg for day 1 and day 7, 4 mg/kg for days 2-6). At 14 days after the termination of drug injection, rats were sacrificed after anesthesia. Brains were removed and sliced into coronal sections (400 [mu]m). The dorsal (caudate putamen, CPu) and ventral (nucleus accumbens, NAc) striatum were dissected in artificial cerebrospinal fluid. A membrane-impermeable cross-linking reagent bis(sulfosuccinimidyl)suberate (BS3) was added. BS3 only cross-links ASICs on the surface of live cells to form high-molecular weight aggregates which can be readily separated from normal intracellular monomer ASIC proteins. Densities of immunoblots were measured using optical scanning and the data were analyzed (t-test (p < 0.05)).
Results: BS3-treated striatal tissue showed a high-molecular weight band of ASIC1 and ASIC2 (surface channels) and a monomeric molecular weight band of ASIC1 and ASIC2 (intracellular channels). Quantification analysis revealed that 70-80% of ASIC1 and ASIC2 are expressed in the surface membrane of normal striatal neurons. Chronic amphetamine administration induced parallel increases in ASIC1 protein levels in both surface and intracellular pools in the CPu at a 14-day withdrawal period. Similar results were also observed in the NAc. In contrast to ASIC1, ASIC2 and [alpha]-actinin in their protein levels remained unchanged in the CPu and NAc of amphetamine-treated rats. Conclusion: These data identified the central ASIC as a sensitive target to repeated stimulant exposure. Discussion: Various synaptic proteins have been screened for their responses to repeated drug exposure. Plastic changes in the expression and function of all responsive proteins are thought to operate in concert to control drug effects. In this study, a new responsive gene is identified. Following repeated amphetamine administration, ASIC expression was regulated in striatal regions. This identifies the channel as an important element of molecular adaptations to drug exposure. Indeed, ASICs have been implicated in various mental disorders1. This study represents an initial effort toward elucidating the precise role of ASICs in processing the addictive action of drugs of abuse.
Neuroscience - Vision and Functional Brain Imaging Poster Session
2010-03-01T00:00:00ZAmphetamine Alters Group I mGluR Expression in the Rat Striatum and Medial Prefrontal Cortex
https://hdl.handle.net/10355/6355
Amphetamine Alters Group I mGluR Expression in the Rat Striatum and Medial Prefrontal Cortex
Shaffer, C. B.; Mao, Li-Min; Fibuch, Eugene; Wang, John Q.
Introduction: Group I metabotropic glutamate receptors (mGluR1/mGluR5 subtypes) and their key scaffolding protein Homer1b/c are densely expressed in the striatum. These receptors are believed to play important roles in the regulation of psychostimulant action. The psychostimulant amphetamine increases extracellular glutamate levels, which in turn activates postsynaptic mGluR1/5 in striatal neurons. It is, however, unclear whether amphetamine has any impact on striatal mGluR1/5 expression. In this study, we hypothesized that alterations in mGluR1/5 and Homer 1b/c expression in the rat striatum and medial prefrontal cortex (mPFC) would occur in response to an acute injection of amphetamine in vivo. Methods: Following IACUC approval, adult male Wistar rats received an intraperitoneal injection of saline (n = 4) or amphetamine (5 mg/kg, n = 5). Motor responses to amphetamine were monitored continuously following drug administration. For detecting gene expression, rats were anesthetized and sacrificed 1 h after saline or amphetamine injection. Brains were removed, and the striatum, including the dorsal (caudate putamen) and ventral (nucleus accumbens) striatum, and mPFC were dissected. Synaptic proteins were extracted for Western blot analysis of changes in mGluR1, mGluR5, and Homer1b/c protein levels with specific antibodies. The density of immunoblots was measured using optical scanning. Data were statistically analyzed using Student's t-test (p<0.05). Results: A single injection of amphetamine induced a typical increase in motor activity, confirming that a behaviorally active dose of the drug was used. At this dose, amphetamine markedly reduced mGluR5 protein levels in the striatum, while increasing mGluR5 protein levels in the mPFC. Unlike mGluR5, mGluR1 protein expression in both the striatum and mPFC was not significantly altered in amphetamine-treated rats relative to saline-treated rats. Homer1b/c protein levels in the two regions also remained stable in response to amphetamine administration. Actin protein levels showed no difference between amphetamine- and saline-treated groups. Conclusion: These data identify mGluR5 as a sensitive target of amphetamine. Acute amphetamine exposure is able to alter striatal mGluR5 expression in a subtype- and region-specific manner.
Discussion: Amphetamine increases glutamate release in the striatum1 which can activate mGluRs in striatal neurons to produce drug effects. Group I mGluRs have been demonstrated to undergo rapid desensitization following ligand stimulation of the receptor1. Thus, our finding of a loss of synaptic mGluR5 after amphetamine suggests a previously unrecognized mechanism for such desensitization. Of note, amphetamine has no effect on glutamate release in the mPFC1. Future studies are needed to define the role of amphetamine-stimulated mGluR5 expression in this region.
Neuroscience - Vision and Functional Brain Imaging Poster Session
2010-03-01T00:00:00ZChronic Fibrotic Changes in Experimental Pulmonary Embolization in the Rat Model
https://hdl.handle.net/10355/6234
Chronic Fibrotic Changes in Experimental Pulmonary Embolization in the Rat Model
Mehrer, M.; Schroeppel, J.; Fibuch, Eugene; Adler, F.; Molteni, A.; Herndon, B.; Lankachandra, K. M.; McIff, T.; Poisner, A. M. (Alan M.)
Introduction: Fat embolism, a subclinical event, occurs in many clinical settings, such as long bones fractures, liposuction and during cardiopulmonary bypass. Some cases, especially with trauma, result in fat embolism syndrome (FES), a serious manifestation of fat embolism. FES is reported to occur in 5-10% of major trauma cases and can produce profound respiratory problems that may culminate in adult respiratory distress syndrome (ARDS). Embolized fat is hydrolyzed by lipase into free fatty acids which have been shown by previous histological studies to be toxic to the lung. An animal model of fat embolism has been developed utilizing triolein given intravenously (i.v.) to rats. We hypothesized that i.v. triolein will produce histological changes in the lung that are similar to the changes seen in human FES.
Methods: Following University animal care approval, unanesthetized Sprague Dawley rats (study n=13, control n=12) were injected with either triolein, 0.2 mL (study) or saline, 0.2 mL (control). Weights were recorded until necropsy at 3 weeks (n=13) and 6 weeks (n=12). Morphometric measurements were made on both H&E and fat-stained tissues from the lungs, heart, kidneys and spleen. All vessels were examined using high magnification fields. Arterial wall thickness (lumen patency) was calculated by vessel luminal and external diameters. The medial-adventitial ratio was calculated from the outer medial diameter divided by the outer adventitial diameter. These values were keyed into statistical software and analysis as a function of time and treatment was calculated using t-tests with significance noted at a p<0.05.
Results: Gross pathological changes were seen in lung, heart, kidneys, liver and spleen of the triolein group. Pulmonary histological examination revealed diffuse intra-alveolar hemorrhages and edema with peri-bronchial inflammation. Vasculitis was more prominent in the peri-bronchial areas as well. Pulmonary arteries revealed significant medial thickening as compared with the control groups with lumen patency p=0.004. Adventitia/media ratio, with large variability in the triolein group, was not statistically significant. Conclusions: Our data showed that injected triolein remains in the rat lung after 3 and 6 weeks with associated vascular and septal damage in the lung tissue compared to controls. Discussion: This study is a continuation of our previous study showing an increase of severe pulmonary damage within 3-6 hours following triolein induced fat embolism in the rat, reaching a peak at 96 hrs post injection. Despite unmedicated recovery of general condition and body weight and reopening of the pulmonary arteries and arterioles, collagen and vasculitis persisted up to 6 weeks. Further studies are needed to verify the eventual recovery or the organ evolution toward chronic fibrosis.
Comparative Medicine - OneHealth and Comparative Medicine Poster Session
2010-03-01T00:00:00ZClearing the hurdles for nanotechnology: In vivo inhalation effects
https://hdl.handle.net/10355/6228
Clearing the hurdles for nanotechnology: In vivo inhalation effects
Herndon, B.; Nalvarte-Kostoryz, Elisabet L. (Elisabet Lourdes), 1958-; Molteni, A.; Quinn, T.; Fibuch, Eugene
INTRODUCTION: Nanoparticles of many types have been created for industrial and medical applications. Among these nanoparticles, single-walled carbon nanotubes (SWCNT) are of high interest for their physicochemical properties and application in electronics, drug delivery and other areas. With the rapid expansion in SWCNT-based new technologies, a full understanding of their safety and risks for human exposure must be considered. Because of the potential human risk of nanoparticle exposure we have developed an animal model to study the effects of nanoparticle exposure on lung tissue. Using this rat model we hypothesized that an acute nanoparticle exposure would result in an inflammatory response in lung tissue. METHODS: Particle instillation (intratracheal under direct visualization) of 50 μL pediatric surfactant containing 500 micrograms SWCNT (or surfactant alone) was performed in 32 rats to date. Pulmonary histology and biochemical measures on bronchoalveolar lavage (BAL), pleural fluid, serum and lung cells was quantified. RESULTS: Very early (<30 minutes) eosinophilia developed in lung tissue following SWCNT instillation. Innate immune system sterile response, or Damage Associated Molecular Patterns (DAMPs) protein was released. Our dose proved sterile, <0.03 EU LPS, showing the effect was damage-induced not pathogen-induced. High mobility group box protein-1 (HMGB1), a nuclear chaperone and prototype DAMP was elevated (ELISA) following SWCNT exposure. A second DAMP, heatshock protein 70 (HSP-70), a cytoplasmic chaperone, was also quantified by ELISA. The response OF HSP-70 over time is similar to HMGB1. Western blots performed on time-harvested lungs exposed to SWCNT demonstrated a receptor for advanced glycation end products (RAGE), with a strong peak at 3 hours after pulmonary exposure. The inflammatory cytokine TNFα appeared in lung tissue and bronchial alveolar lavage (BAL) at 30 minutes, with the same timing as the HMGB1 and HSP-70 release. Flow cytometry of type II pneumocytes and pulmonary macrophages from SWCNT-exposed rats demonstrated secondary DAMP receptors. A potential chronic effect was noted at one month. HMGB1 and HSP-70 peaked acutely at approximately 24 hr and then slowly decreased at 1 to 2 weeks. At 1 month, however, a new increase was seen. CONCLUSIONS: The hydrophobic SWCNT, important industrial components, form bundles and fibers in the hydrophilic lung, creating an immediate cellular inflammatory response, measurable cellular necrosis and very rapid chemokine release. Early data suggests the potential for chronicity.
Nanoparticle Poster Session
2010-03-01T00:00:00Z