EXAMINING THE BEHAVIORAL AND PHYISIOLGICAL EFFECTS OF D-METHAMPHETAMINE ADMINISTERED VIA E-CIGARETTE AEROSOLIZATION

Abstract EXAMINING THE BEHAVIORAL AND PHYISIOLGICAL EFFECTS OF D-METHAMPHETAMINE ADMINISTERED VIA E-CIGARETTE AEROSOLIZATION By Srikethan Mahavadi, B.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University Virginia Commonwealth University, 2021 Principal Investigator: Dr. Keith Shelton, PhD., Department of Pharmacology & Toxicology E-cigarettes have become increasing popular worldwide. They are primarily used as a means to deliver nicotine to users, but these devices may also be used to administer a wide range of other substances including psychomotor stimulants such as d-methamphetamine. Methamphetamine has been widely abused throughout the United States and across the world leading us to believe there may be a possibility of abuse potential resulting from aerosolization of methamphetamine via e-cigarettes. In the present thesis, methamphetamine aerosol’s CNS-mediated behavioral effects were assessed using locomotor activity, sympathomimetics effects examined using physiological testing, and drug blood levels after aerosolized methamphetamine was assayed. Key user controllable parameters of e-cigarette which may impact abuse liability such as puff number and e-cigarette wattage were manipulated. The locomotor assay revealed dose-dependent effects on total distance traveled following methamphetamine administered subcutaneously (at doses of 0.03, 0.1, and 0.3 mg/kg) as well as puff (1, 5, 10, 15, 20) and wattage (18 and 36 watt) dependent changes in locomotor after exposure to 30 mg/ml aerosolized methamphetamine. Physiological effects measuring blood pressure (systolic and diastolic), body temperature, and heart rate showed puff-dependent increases in blood pressure and body temperature; however, heart rate did not show similar results. Finally, methamphetamine plasma concentration levels were also puff dependent as the greater the number of puffs the higher the concentration of methamphetamine in plasma was detected. All of these results were similar or in some cases greater than our positive subcutaneously administered methamphetamine control suggesting that methamphetamine may have high abuse liability when administered using e-cigarettes

Nicotine-Induced Effects on Nicotinic Acetylcholine Receptors (nAChRs), Ca2+ and Brain-Derived Neurotrophic Factor (BDNF) in STC-1 Cells

In addition to the T2R bitter taste receptors, neuronal nicotinic acetylcholine receptors (nAChRs) have recently been shown to be involved in the bitter taste transduction of nicotine, acetylcholine and ethanol. However, at present it is not clear if nAChRs are expressed in enteroendocrine cells other than beta cells of the pancreas and enterochromaffin cells, and if they play a role in the synthesis and release of neurohumoral peptides. Accordingly, we investigated the expression and functional role of nAChRs in enteroendocrine STC-1 cells. Our studies using RT-PCR, qRT-PCR, immunohistochemical and Western blotting techniques demonstrate that STC-1 cells express several α and β nAChR subunits. Exposing STC-1 cells to nicotine acutely (24h) or chronically (4 days) induced a differential increase in the expression of nAChR subunit mRNA and protein in a dose- and time-dependent fashion. Mecamylamine, a non-selective antagonist of nAChRs, inhibited the nicotineinduced increase in mRNA expression of nAChRs. Exposing STC-1 cells to nicotine increased intracellular Ca2+ in a dose-dependent manner that was inhibited in the presence of mecamylamine or dihydro-β-erythroidine, a α4β2 nAChR antagonist. Brain-derived neurotrophic factor (BDNF) mRNA and protein were detected in STC-1 cells using RT-PCR, specific BDNF antibody, and enzyme-linked immunosorbent assay. Acute nicotine exposure (30 min) decreased the cellular content of BDNF in STC-1 cells. The nicotine-induced decrease in BDNF was inhibited in the presence of mecamylamine. We also detected α3 and β4 mRNA in intestinal mucosal cells and α3 protein expression in intestinal enteroendocrine cells. We conclude that STC-1 cells and intestinal enteroendocrine cells express nAChRs. In STC-1 cells nAChR expression is modulated by exposure to nicotine in a doseand time-dependent manner. Nicotine interacts with nAChRs and inhibits BDNF expression in STC-1 cells

Negative storm surges in the Elbe estuary — Large-scale meteoro-logical conditions and future climate change

This article belongs to the Special Issue "Impacts of Climate Change on Transportation Infrastructure, Networks and Nodes"; https://www.mdpi.com/journal/atmosphere/special_issues/climate_transportatio

Cyclic-AMP regulates postnatal development of neural and behavioral responses to NaCl in rats

During postnatal development rats demonstrate an age-dependent increase in NaCl chorda tympani (CT) responses and the number of functional apical amiloride-sensitive epithelial Na+channels (ENaCs) in salt sensing fungiform (FF) taste receptor cells (TRCs). Currently, the intracellular signals that regulate the postnatal development of salt taste have not been identified. We investigated the effect of cAMP, a downstream signal for arginine vasopressin (AVP) action, on the postnatal development of NaCl responses in 19–23 day old rats. ENaC-dependent NaCl CT responses were monitored after lingual application of 8-chlorophenylthio-cAMP (8-CPT-cAMP) under open-circuit conditions and under ±60 mV lingual voltage clamp. Behavioral responses were tested using 2 bottle/24h NaCl preference tests. The effect of [deamino-Cys1, D-Arg8]-vasopressin (dDAVP, a specific V2R agonist) was investigated on ENaC subunit trafficking in rat FF TRCs and on cAMP generation in cultured adult human FF taste cells (HBO cells). Our results show that in 19–23 day old rats, the ENaC-dependent maximum NaCl CT response was a saturating sigmoidal function of 8-CPT-cAMP concentration. 8-CPT-cAMP increased the voltage-sensitivity of the NaCl CT response and the apical Na+ response conductance. Intravenous injections of dDAVP increased ENaC expression and γ-ENaC trafficking from cytosolic compartment to the apical compartment in rat FF TRCs. In HBO cells dDAVP increased intracellular cAMP and cAMP increased trafficking of γ- and δ-ENaC from cytosolic compartment to the apical compartment 10 min post-cAMP treatment. Control 19–23 day old rats were indifferent to NaCl, but showed clear preference for appetitive NaCl concentrations after 8-CPT-cAMP treatment. Relative to adult rats, 14 day old rats demonstrated significantly less V2R antibody binding in circumvallate TRCs. We conclude that an age-dependent increase in V2R expression produces an AVP-induced incremental increase in cAMP that modulates the postnatal increase in TRC ENaC and the neural and behavioral responses to NaCl

Release of GLP-1 and PYY in response to the activation of G protein-coupled bile acid receptor TGR5 is mediated by Epac/PLC-ε pathway and modulated by endogenous H2S

Activation of plasma membrane TGR5 receptors in enteroendocrine cells by bile acids is known to regulate gastrointestinal secretion and motility and glucose homeostasis. The endocrine functions of the gut are modulated by microenvironment of the distal gut predominantly by sulfur-containing bacteria of the microbiota that produce H2S. However, the mechanisms involved in the release of peptide hormones, GLP-1 and PYY in response to TGR5 activation by bile acids and the effect of H2S on bile acid-induced release of GLP-1 and PYY are unclear. In the present study, we have identified the signaling pathways activated by the bile acid receptor TGR5 to mediate GLP-1 and PYY release and the mechanism of inhibition of their release by H2S in enteroendocrine cells. The TGR5 ligand oleanolic acid (OA) stimulated Gs and cAMP formation, and caused GLP-1 and PYY release. OA-induced cAMP formation and peptide release were blocked by TGR5 siRNA. OA also caused an increase in PI hydrolysis and intracellular Ca2+. Increase in PI hydrolysis was abolished in cells transfected with PLC-ε siRNA. 8-pCPT-2’-O-Me-cAMP, a selective activator of Epac, stimulated PI hydrolysis, and GLP-1 and PYY release. L-Cysteine, which activates endogenous H2S producing enzymes cystathionine--lyase and cystathionine--synthase, and NaHS and GYY4137, which generate H2S, inhibited PI hydrolysis and GLP-1 and PYY release in response to OA or 8-pCPT-2’-O-Me-cAMP. Propargylglycine, an inhibitor of CSE, reversed the effect of L-cysteine on PI hydrolysis and GLP-1 and PYY release. We conclude: i) activation of Gs-coupled TGR5 receptors causes stimulation of PI hydrolysis, and release of GLP-1 and PYY via a PKA-independent, cAMP-dependent mechanism involving Epac/PLC-/Ca2+ pathway, and ii) H2S has potent inhibitory effects on GLP-1 and PYY release in response to TGR5 activation, and the mechanism involves inhibition of PLC-/Ca2+ pathway

Einfluss der Topographie des Wattenmeeres auf Sturmfluten in der Tideelbe im Klimawandel

Vorhersage und ProjektionIm Rahmen des BMVI-Expertennetzwerks Themenfeld 1 „Verkehrs- und Infrastruktur an Klimawandel und extreme Wetterereignisse anpassen“ untersucht die Bundesanstalt für Wasserbau Hamburg u.a. die Bedeutung von Meeresspiegelanstieg und Topographieänderungen in der Deutschen Bucht und ihren Ästuaren. Der Meeresspiegelanstieg beeinflusst die Hydrodynamik in den Ästuaren und somit sowohl mittlere Tiden, als auch Sturmflutereignisse. Da das Küstenprofil in einem morphodynamischen Gleichgewicht mit den hydrodynamischen Kräften steht, kann sich jedoch auch die Topographie eines Küstengebietes durch den Meeresspiegelanstieg verändern. Die Wattflächen der Deutschen Bucht, welche eine wichtige Komponente des Küstenschutzes sind, können, bei ausreichender Sedimentverfügbarkeit, zu einem gewissen Anteil mit dem Meeresspiegelanstieg mitwachsen. Der Einsatz hydrodynamisch-numerischer Modelle ermöglicht es, den Einfluss der genannten Prozesse auf z. B. Sturmflutscheitelwasserstände einzeln zu untersuchen. In einer Sensitivitätsstudie analysieren wir den Einfluss eines Meeresspiegelanstiegs und einer topographischen Erhöhung der Wattflächen auf Sturmflutereignisse in der Tideelbe. Die Ergebnisse zeigen, dass der Sturmflutscheitelwasserstand (HW) in der Tideelbe etwas höher ansteigt als der am Modellrand eingesteuerte Meeresspiegelanstieg. Eine Erhöhung der Wattflächen führt zu einem Absinken des HW gegenüber einem Szenario mit alleinigem Meeresspiegelanstieg ohne Topographieänderung. Die Berechnung weiterer Analysegrößen, wie der Durchflussfläche, ermöglicht ein besseres Systemverständnis der untersuchten Änderungen in der Tideelbe. Die Untersuchungen verdeutlichen die positiven Auswirkungen eines Wattwachstums bei Meeresspiegelanstieg auf den Küstenschutz und die Notwendigkeit, einem Verlust an Wattflächen durch den Klimawandel entgegenzuwirken