Similar properties of [35S] t-butylbicyclophosphorothionate receptor and coupled components of the gaba receptor-ionophore complex in brains of human, cow, rat, chicken and fish

doi:10.1016/0024-3205(84)90272-8

Life Sciences

Volume 35, Issue 17, 22 October 1984, Pages 1755-1762

https://doi.org/10.1016/0024-3205(84)90272-8 Get rights and content

Abstract

No significant differences are evident in the specific binding characteristics of [³⁵S] $t$ -butylbicyclophosphorothionate ([³⁵S]TBPS) to EDTA/water-dialyzed P₂ membranes of human, cow, rat, chicken and fish brain. This species similarity includes dissociation constants of 61–77 nM at 37°C, maximum receptor densities of 3–7 pmol/mg protein, and sensitivity to inhibition or displacement by γ-aminobutyric acid (GABA), two cage convulsants (picrotoxinin and $t$ -butylbicycloorthobenzoate) and the insecticide [1R, $cis$ , αS]-cypermethrin, indicating a constancy during vertebrate evolution of the [³⁵S]TBPS binding site and its coupling with other components of the GABA receptor-ionophore complex. As a possible exception, chicken and fish brain membranes appear to be less sensitive than the others to the insecticide α-endosulfan. Human and rat preparations are also essentially identical relative to the inhibition of radioligand binding by two GABA mimetics (muscimol and 3-amino-propanesulfonic acid), six other cage convulsants (including examples of three classes of polychlorocycloalkane insecticides), a potent anthelmintic agent (Ivermectin), dimethylbutylbarbiturate, the convulsant benzodiazepine Ro 5–3663, and ethanol. The findings to date with [³⁵S]TBPS and the GABA receptor-ionophore complex in rat brain membranes are therfore generally applicable to human preparations. Cow brain is an appropriate source for large scale preparations in receptor purification studies since it is essentially identical to human and rat preparations in all parameters examined. Species differences in sensitivity to the toxic effects of the convulsants and polychlorocycloalkane insecticides considered are apparently not attributable to receptor site specificity.

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^☆: This research was supported in part by NIH grant PO1 ES00049.

^∗∗: Current address: Department of Pharmacology, University of Arizona Health Sciences Center, Tucson, Arizona 85724.

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Similar properties of [35S] t-butylbicyclophosphorothionate receptor and coupled components of the gaba receptor-ionophore complex in brains of human, cow, rat, chicken and fish☆

Abstract

Life Sci.

Eur. J. Pharmacol.

Eur. J. Pharmacol

Life Sci.

Life Sci.

Toxicol. Appl. Pharmacol.

Anal. Biochem.

Neuroscience Lett.

Prog. Neurobiol.

Brain Res.

Toxicol. Appl. Pharmacol.

Similar properties of [³⁵S] $t$ -butylbicyclophosphorothionate receptor and coupled components of the gaba receptor-ionophore complex in brains of human, cow, rat, chicken and fish☆