Daniel J Calvo

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Benzodiazepines (BDZs) are the most widely prescribed class of psychoactive drugs in current therapeutic use, despite the important unwanted side-effects that they produce such as sedation, myorelaxation, ataxia, amnesia, ethanol and barbiturate potentiation and tolerance. Searching for safer BDZ-receptor (BDZ-R) ligands we have recently demonstrated the(More)
The dopamine D4 receptor (D4R) has received considerable interest because of its higher affinity for atypical antipsychotics, the extremely polymorphic nature of the human gene and the genetic association with attention deficit and hyperactivity disorder (ADHD). Several efforts have been undertaken to determine the D4R expression pattern in the brain using(More)
The modulation of ionotropic gamma-aminobutyric acid (GABA) receptors (GABA-gated Cl(-) channels) by a group of natural and synthetic flavonoids was studied in electrophysiological experiments. Quercetin, apigenin, morine, chrysin and flavone inhibited ionic currents mediated by alpha(1)beta(1)gamma(2s) GABA(A) and rho(1) GABA(C) receptors expressed in(More)
Neurons of the vertebrate retina possess receptors for many neurotransmitters. Particularly interesting is a new type of GABA receptor (GABA rho) that, in contrast to GABAA and GABAB receptors, shows very little desensitization, is not blocked by bicuculline, and is not activated by baclofen. Homomeric human GABA rho 1 receptors were expressed in Xenopus(More)
Chrysin (5,7-di-OH-flavone) was identified in Passiflora coerulea L., a plant used as a sedative in folkloric medicine. Chrysin was found to be a ligand for the benzodiazepine receptors, both central (Ki = 3 microM, competitive mechanism) and peripheral (Ki = 13 microM, mixed-type mechanism). Administered to mice by the intracerebroventricular route,(More)
1. The mechanisms of action of antagonists of the gamma-aminobutyric acid C (GABA(C)) receptor picrotoxin, quercetin and pregnanolone were studied. 2. Ionic currents (chloride), mediated through human homomeric GABA rho(1) receptors expressed in Xenopus oocytes, were recorded by two-electrode voltage clamp. 3. Dose-response (D-R) curves and kinetic(More)
We studied the functional activation of different polymorphic variants of the human dopamine D(4) receptors by the three major central monoamines, dopamine, noradrenaline and serotonin. Dopamine D(4) receptors carrying two (D4.2), four (D4.4) or seven (D4.7) repeats within the third intracellular domain were co-expressed with G protein-regulated inwardly(More)
The long-term effects of the systemic administration of DSP4 (N-(2-chloroethyl)N-ethyl-2-bromobenzylamine hydrochloride), a selective noradrenergic neurotoxin, on the endogenous levels of monoamines and their metabolites and on alpha- and beta-adrenoceptors in selected brain regions of the rat were examined. After 7 days, DSP4 caused a marked reduction(More)
Fifteen minutes after the initiation of swimming stress in the rat we observed a 50% increase in the number of [3H]RO 5-4864 binding sites in kidney and a 37% increase in the olfactory bulb, without change in affinity. The binding in heart and cerebral cortex remained unchanged after the stress. These results are discussed in relation to previous work on(More)
The activity of many receptors and ion channels in the nervous system can be regulated by redox-dependent mechanisms. Native and recombinant GABA(A) receptors are modulated by endogenous and pharmacological redox agents. However, the sensitivity of GABA(C) receptors to redox modulation has not been demonstrated. We studied the actions of different reducing(More)