Browsing by Author "Cassels, BK"

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    Aleph2, a Suspected Anxiolytic and Putative Hallucinogenic Phenylisopropylamine Derivative, Is a 5-Ht2a and 5-Ht2c Receptor Agonist
    (2000) Acuña-Castillo, C; Scorza, C; Reyes-Parada, M; Cassels, BK; Huidobro-Toro, JP
    To assess the pharmacodynamic profile of ALEPH-2, a phenylisopropylamine derivative with alleged anxiolytic and hallucinogenic properties,Xenopus laevis oocytes were microinjected with either of the rat cRNA for the 5-HT2A or the 5-HT2C receptor. Concentration-response curves were obtained following the exposure of the oocytes to varying concentrations of either ALEPH-2 or 5-hydroxy-tryptamine (5-HT) for 10 s. ALEPH-2 is a partial agonist on the 5-HT,,receptor with a similar potency to 5-HT. In contrast, ALEPH-2 is a full 5-HT2C receptor agonist and is about 15-fold less potent than 5-HT. Pre-application of 1 muM ritanserin antagonized the responses induced by 5-HT and ALEPH-2 to the same extent; however, the 5-HT2A receptor is more sensitive to ritanserin blockade than the 5-HT2C receptor. (C) 2000 Elsevier Science Inc. All rights reserved.
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    Differences in potency and efficacy of a series of phenylisopropylamine/phenylethylamine pairs at 5-HT2A and 5-HT2C receptors
    (2002) Acuña-Castillo, C; Villalobos, C; Moya, PR; Sáez, P; Cassels, BK; Huidobro-Toro, J
    1 The pharmacological profile of a series of (+/-)-2,5-dimethoxy-4-(X)-phenylisopropylamines (X = I, Br, NO2, CH3, or H) and corresponding phenylethylamines, was determined in Xenopus laevis oocytes injected with cRNA coding for rat 5-HT2A or 5-HT2C receptors. The efficacy and relative potency of these drugs were determined and compared to classical 5-HT2 receptor agonists and antagonists.
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    Electrophysiological characterization of nicotinic acetylcholine receptors in cat petrosal ganglion neurons in culture
    (2006) Varas, R; Valdés, V; Iturriaga-Vásquez, P; Cassels, BK; Iturriaga, R; Alcayaga, J
    Petrosal ganglion neurons are depolarized and fire action potentials in response to acetylcholine and nicotine. However, little is known about the subtype(s) of nicotinic acetylcholine receptors involved, although alpha 4 and alpha 7 subunits have been identified in petrosal ganglion neurons. Cytisine, an alkaloid unrelated to nicotine, and its bromo derivatives are agonists exhibiting different affinities, potencies and efficacies at nicotinic acetylcholine receptors containing a4 or 0 subunits. To characterize the receptors involved, we studied the effects of these agonists and the nicotinic acetylcholine receptor antagonists hexamethonium and alpha-bungarotoxin in isolated petrosal ganglion neurons. Petrosal ganglia were excised from anesthetized cats and cultured for up to 16 days. Using patch-clamp technique, we recorded whole-cell currents evoked by 5-10 s applications of acetylcholine, cytisine or its bromo derivatives. Agonists and antagonists were applied by gravity from a pipette near the neuron surface. Neurons responded to acetylcholine, cytisine, 3-bromocytisine and 5-bromocytisine with fast inward currents that desensitized during application of the stimuli and were reversibly blocked by 1 mu M hexamethoniurn or 10 nM alpha-bungarotoxin. The order of potency of the agonists was 3-bromocytisine >> acetylcholine congruent to cytisine >> 5-bromocytisine, suggesting that homomeric alpha 7 neuronal nicotinic receptors predominate in cat petrosal ganglion neurons in culture. (c) 2005 Elsevier B.V. All rights reserved.
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    Regioselectivity in the Diels-Alder reaction of 8,8-dimethylnaphthalene-1,4,5(8H)-trione with 2,4-hexadien-1-ol
    (1999) Araya-Maturana, R; Cassels, BK; Delgado-Castro, T; Valderrama, JA; Weiss-López, BE
    The Diels-Alder reactions of 8,8-dimethylnaphtalene-1,4,5(8H)-trione with 2,4-hexadien-1-ol and its O-acetyl derivative were investigated in different solvents. The regiochemistry of the cycloaddition of the hexadienol was determined through chemical correlation of one of the products. The solvent effect on the regioselectivity and endo/exo selectivity of this reaction is attributed to intermolecular hydrogen bonding between the hydroxyl group of the diene and the carbonyl oxygen atoms at C-4 and C-5 of the quinone in the transition state. The possible transition states have been modelled by AMI calculations in order to better interpret these experimental results. (C) 1998 Elsevier Science Ltd. All rights reserved.