title: Gamma aminobutyric acid radioreceptor-assay a possible biomarker for human exposure to certain agrochemicals.
abstract: Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the gamma-aminobutyric acid (GABA)A receptor-ionophore sites. [35S] tertiary-butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABAA receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centrifugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [35S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the alpha-endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8 x 10(-11) gm of endosulfan in each ml of the blood samples.
authors.affiliation: Department of Chemistry, Texas Southern University, Houston 77004.
authors.forename: M A
authors.initials: MA
authors.lastname: Saleh
authors.forename: M
authors.initials: M
authors.lastname: Abou Zied
authors.forename: G
authors.initials: G
authors.lastname: el-Baroty
authors.forename: E
authors.initials: E
authors.lastname: Abdel-Reheim
authors.forename: F
authors.initials: F
authors.lastname: Abdel-Rahman
authors.forename: C
authors.initials: C
authors.lastname: Wallace
authors.forename: A H
authors.initials: AH
authors.lastname: el-Sebae
authors.forename: J N
authors.initials: JN
authors.lastname: Blancato
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D001643:Bridged Bicyclo Compounds / Q000097:blood; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002417:Cattle; D003292:Convulsants / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004726:Endosulfan / Q000097:blood; D004781:Environmental Exposure; D006041:Goats; D006801:Humans; D007059:Ictaluridae; D007306:Insecticides / Q000032:analysis*; D008297:Male; D010573:Pesticide Residues / Q000032:analysis*; D011869:Radioligand Assay / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013329:Structure-Activity Relationship
chemical_list: D001643:Bridged Bicyclo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003292:Convulsants; D007306:Insecticides; D010573:Pesticide Residues; D011963:Receptors, GABA-A; C037476:tert-butylbicyclophosphorothionate; D004726:Endosulfan