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Prolonged nicotine exposure down-regulates presynaptic NMDA receptors in dopami...
Salamone, Alessia; Zappettini, Stefania; Grilli, Massimo; Guendalina, Paula; Tomé, Angelo R.; Chen, Jiayang; Pittaluga, Anna; Cunha, Rodrigo A.The presynaptic control of dopamine release in the nucleus accumbens (NAc) by glutamate and acetylcholine has a profound impact on reward signaling. Here we provide immunocytochemical and neurochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs) and N-methyl-D-aspartic acid (NMDA) receptors in dopaminergic terminals of the NAc. Most NAc d...
Regulation by glucose of oscillatory electrical activity and 5-HT/insulin relea...
Rosário, Luís M.; Barbosa, Rui M.; Antunes, Célia M.; Baldeiras, Inês E.; Silva, Amélia M.; Tomé, Ângelo R.; Santos, Rosa M.The glucose sensitivity of bursting electrical activity and pulsatile insulin release from pancreatic islets was determined in absence of functional KATP channels. Membrane potential, [Ca2+]i and 5-HT/insulin release were measured by intracellular recording, fura-2 fluorescence and 5-HT amperometry, respectively. Single mouse islets, bathed in tolbutamide or glibenclamide and high extracellular Ca2+ (Ca2+o), di...
Regulation by glucose of oscillatory electrical activity and 5-HT/insulin relea...
Antunes, Célia M.; Rosário, Luís M.; Barbosa, Rui M.; Silva, Amélia S.; Baldeiras, Inês E.; Tomé, Ângelo R.; Santos, Rosa M.The glucose sensitivity of bursting electrical activity and pulsatile insulin release from pancreatic islets was determined in absence of functional KATP channels. Membrane potential, [Ca2+]i and 5- HT/insulin release were measured by intracellular recording, fura-2 fluorescence and 5-HT amperometry, respectively. Single mouse islets, bathed in tolbutamide or glibenclamide and high extracellular Ca2+ (Ca2+o), d...
Selective stimulation of catecholamine release from bovine adrenal chromaffin c...
Tomé, Ângelo R.; Castro, Enrique; Santos, Rosa M.; Rosário, Luís M.Background 2-Methylthioadenosine 5'-triphosphate (2-MeSATP), formerly regarded as a specific P2Y (metabotropic) purinergic receptor agonist, stimulates Ca2+ influx and evokes catecholamine release from adrenal chromaffin cells. These cells express P2Y and P2X (ionotropic) purinoceptors, with the latter providing an important Ca2+ influx pathway. Using single cell calcium imaging techniques, we have determined ...
Functional distribution of Ca2+-coupled P2 purinergic receptors among adrenergi...
Tomé, Ângelo R.; Castro, Enrique; Santos, Rosa M.; Rosário, Luís M.Background Adrenal chromaffin cells mediate acute responses to stress through the release of epinephrine. Chromaffin cell function is regulated by several receptors, present both in adrenergic (AD) and noradrenergic (NA) cells. Extracellular ATP exerts excitatory and inhibitory actions on chromaffin cells via ionotropic (P2X) and metabotropic (P2Y) receptors. We have taken advantage of the actions of the purin...
Naloxone inhibits nicotine-induced receptor current and catecholamine secretion...
Tomé, Angelo R.; Izaguirre, Victor; Rosário, Luís M.; Ceña, Valentín; González-García, CarmenNicotine-induced catecholamine (CA) secretion and inward ionic currents were inhibited by the opioid antagonist naloxone in cultured bovine chromaffin cells. Naloxone inhibited nicotine-induced CA secretion, as detected by an on-line real-time electrochemical technique, in a dose-dependent manner (IC50=29 [mu]M). In voltage-clamped chromaffin cells, nicotine (10 [mu]M) evoked an average peak inward current of -...
Glucose-mediated Ca2+ signalling in single clonal insulin-secreting cells: evid...
Salgado, António P.; Santos, Rosa M.; Fernandes, Ana P.; Tomé, Angelo R.; Flatt, Peter R.; Rosário, Luís M.Using clonal insulin-secreting BRIN-BD11 cells, we have assessed whether the graded response of the whole cell population to glucose can be accounted for by a dose-dependent recruitment of individual cells, an amplification of the response of the recruited cells or both. Cytosolic free Ca2+ concentration ([Ca2+]i) is an established index of [beta]-cell function. We used fura-2 microfluorescence techniques to as...
Control of pulsatile 5-HT/insulin secretion from single mouse pancreatic islets...
Barbosa, Rui M.; Silva, Amélia M.; Tomé, Angelo R.; Stamford, Jonathan A.; Santos, Rosa M.; Rosário, Luís M.Glucose-induced insulin release from single islets of Langerhans is pulsatile. We have investigated the correlation between changes in cytosolic free calcium concentration ([Ca2+]i) and oscillatory insulin secretion from single mouse islets, in particular examining the basis for differences in secretory responses to intermediate and high glucose concentrations. Insulin release was monitored in real time through...
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