Biomedical subjects

C Suñol

Publications and source records attributed to C Suñol.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Lindane inhibition of [35S]TBPS binding to the GABAA receptor in rat brain.

The inhibition of [35S]t-butylbicyclophosphorothionate [( 35S]TBPS) binding to the GABAA receptor by the insecticide gamma-hexachlorocyclohexane, lindane, was studied in several brain regions and using different membrane preparation methods, both in vitro and after dosing the animals with the chemical. In the latter studies, the amount of lindane remaining in the membrane suspensions used for binding assays was determined. In vitro data showed values of IC50 from 150 to 1675 nM, varying in function of the membrane preparation method used. This may account for the discrepancies in IC50 values found in the literature. IC50 values within the range of 150-250 nM were determined using extensively washed membranes from several brain regions, so no evidence arose for brain regional differences in the affinity of lindane for the TBPS binding site. After different schedules of acute treatment with lindane, we found a manifest relationship between the extent of the observable inhibition of [35S]TBPS binding and the lindane amount remaining in the membrane suspensions used for binding assays. This relationship was in good agreement with the in vitro data, so no support for an in vivo acute regulation of the binding site was obtained.

Animals↗

PubMedDate not supplied

On the effects of lindane on the plus-maze model of anxiety.

The behavioral effects of an acute subconvulsant dose of the insecticide and ectoparasiticide gamma-hexachlorocyclohexane, lindane, were compared in the plus-maze ((+)-maze) animal model of anxiety to those elicited by the anxiogenic GABAA-antagonist pentylenetetrazole (PTZ) and the anxiolytic benzodiazepine diazepam. The effects of the coadministration of diazepam and lindane, and of diazepam and PTZ were also studied. The results from the analysis of the data with the multivariate statistical technique principal component analysis indicated that the effects of subconvulsant doses of lindane and PTZ on the behavior of rats in the (+)-maze are similar, and opposite to those elicited by diazepam, and that the administration of the convulsants would antagonize the effects of the benzodiazepine. The putative anxiogenic properties of the insecticide and the utility of the (+)-maze model in neurotoxicological research are discussed.

Animals↗

PubMedDate not supplied

Behavioral and monoaminergic changes after lindane exposure in developing rats.

The effects of lindane on behavior and central monoaminergic systems were studied in rat pups at 15 days of postnatal age. Pups were previously given nonconvulsant lindane PO doses, either a single 20 mg/kg or 7-day repeated 10 mg/kg doses. Both treatment schedules improved the passive avoidance acquisition but only the acute administration prolonged the step-through latency. Acute lindane decreased the motor activity, whereas the repeated dosing increased it. Increases of the ratio 5-HIAA/serotonin in several brain regions and of the ratio DOPAC/dopamine in the mesencephalon after a single dose of lindane suggest an enhanced monoaminergic turnover. In contrast, repeated lindane doses decreased monoamine/metabolite ratios excluding the striatum, where an increase of DOPAC/dopamine ratio correlates with the higher motor activity of these animals. It is postulated that both the imbalance of the central monoaminergic systems and the lindane-induced GABAergic blockade may be the basis of the behavioral alterations.

Animals↗

PubMedDate not supplied

Polychlorocycloalkane insecticide action on GABA-and glycine-dependent chloride flux.

The inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and glycine directly cause an increase in conductance to Cl- by binding to ligand-operated ion channel receptors at the postsynaptic membranes, so that opening of Cl- channels usually leads to a net hyperpolarization. The GABA(A) receptor has separate but allosterically interacting binding sites for GABA, benzodiazepines, barbiturates, anesthetic steroids and the convulsant picrotoxinin. The GABA(C) receptor also forms a Cl- channel, however its pharmacology differs from that of the GABA(A) receptor. Neurotoxic organochlorine pesticides belonging to the group of polychlorocycloalkanes (cyclodienes and gamma-hexachlorocyclohexane or lindane) induce in mammals an hyperexcitability syndrome that can progress until the production of tonic-clonic convulsions. They act as non-competitive GABA antagonists interacting with the picrotoxinin site both in membranes and in intact cultured neurons, thereby inhibiting the GABA-induced Cl- flux following activation of either GABA(A) or GABA(C) receptors. We also report the effects of polychlorocycloalkanes on glycine-induced 36Cl- flux in primary neuronal cultures. The delta isomer of hexachlorocyclohexane is a depressant compound, that increases the GABA-induced Cl- flux and allosterically increases benzodiazepine binding at the GABA(A) receptor. We discuss the mechanism of action of these compounds in relation to the disruption of ligand-operated Cl- channel receptors and the relevance of their convulsant/depressant actions.

Animals↗