Characterization of binding sites for [3H]Gaba in Drosophila melanogaster CNS membranes

Rosario, Paula; Barat, Ana; Ramı́rez, Galo

doi:10.1016/0197-0186(89)90083-1

Cited by 4 publications

(5 citation statements)

References 20 publications

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“…3-APS was the least potent agonist of RDLac tested in the present study and was 100 fold less potent than GABA. Finally, the relative potencies of muscimol, GABA, isonipecotic acid, I-4-AA, /3-alanine and bicuculline on RDLac homo-oligomers resemble those observed in radioligand binding studies on native Drosophila GABA receptors (Rosario et al, 1989). It therefore appears that the agonist site pharmacology of RDLac and DRC 17-1-2 homo-oligomers is characteristic of that of native, bicuculline-insensitive GABA receptors from a variety of insect species.…”

Section: Resultsmentioning

confidence: 64%

Agonist pharmacology of two Drosophila GABA receptor splice variants

Hosie

Sattelle

1996

British J Pharmacology

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1 The Drosophila melanogaster y-aminobutyric acid (GABA) receptor subunits, RDLaC and DRC 17-1-2, form functional homo-oligomeric receptors when heterologously expressed in Xenopus laevis oocytes. The subunits differ in only 17 amino acids, principally in regions of the N-terminal domain which determine agonist pharmacology in vertebrate ionotropic neurotransmitter receptors. A range of conformationally restricted GABA analogues were tested on the two homo-oligomers and their agonist pharmacology compared with that of insect and vertebrate iontropic GABA receptors. 2 The actions of GABA, isoguvacine and isonipecotic acid on RDLaC and DRC 17-1-2 homo-oligomers were compared, by use of two-electrode voltage-clamp. All three compounds were full agonists of both receptors, but were 4-6 fold less potent agonists of DRC 17-1-2 homo-oligomers than of RDLaC. However, the relative potencies of these agonists on each receptor were very similar.3 A more complete agonist profile was established for RDLac homo-oligomers. The most potent agonists of these receptors were GABA, muscimol and trans-aminocrotonic acid (TACA), which were approximately equipotent. RDLaC homo-oligomers were fully activated by a range of GABA analogues, with the order of potency: GABA> ZAPA ((Z)-3-[(aminoiminomethyl)thio]prop-2-enoic acid)> isoguvacine > imidazole-4-acetic acid > isonipecotic acid > cis-aminocrotonic acid (CACA) > P-alanine. 3-Aminopropane sulphonic acid (3-APS), a partial agonist of RDLLC homo-oligomers, was the weakest agonist tested and 100 fold less potent than GABA. 4 SR95531, an antagonist of vertebrate GABAA receptors, competitively inhibited the GABA responses of RDLaC homo-oligomers, which have previously been found to be insensitive to bicuculline. However, its potency (IC50 500 gM) was much reduced when compared to GABAA receptors.5 The agonist pharmacology of Drosophila RDLac homo-oligomers exhibits aspects of the characteristic pharmacology of certain native insect GABA receptors which distinguish them from vertebrate GABA receptors. The high potency and efficacy of isoguvacine and ZAPA distinguishes RDLIC homo-oligomers from bicuculline-insensitive vertebrate GABAC receptors, while the low potency of SR95531 and 3-APS distinguishes them from GABAA receptors. The differences in the potency of agonists on RDLaC and DRC 17-1-2 homo-oligomers observed in the present study may assist in identification of further molecular determinants of GABA receptor function.

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Section: Resultsmentioning

confidence: 64%

Agonist pharmacology of two Drosophila GABA receptor splice variants

Hosie

Sattelle

1996

British J Pharmacology

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“…26 Notably, the B max and K d values of FF binding to the M. domestica GABARs were 21.3 ± 2.5 pmol/ mg of protein and 109 ± 9 nM, respectively, in good agreement with previous reports from Abalis et al 27 and Rosario et al 28 In the radioisotopic labeling assay, the K d values of fipronil binding to the GABARs of M. domestica were 24.3 and 23 nM, respectively. 27,28 Therefore, the superior affinity of fipronil for GABARs in M. domestica may underlie the high fipronil toxicity in insects. Moreover, the above results showed that fipronil exhibited high affinity for fish GABARs, which may be responsible for the high toxicity of fipronil to fish.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the obtained K d value was far less than that of fipronil binding to mammalian GABARs ( K d = 16 μM in the receptor stimulation state, K d = 26 μM in the receptor closed state) but similar to that of fipronil binding to insect GABARs ( K d = 179 nM in the receptor stimulation state, K d = 98 nM in the receptor closed state) . Notably, the B max and K d values of FF binding to the M. domestica GABARs were 21.3 ± 2.5 pmol/mg of protein and 109 ± 9 nM, respectively, in good agreement with previous reports from Abalis et al and Rosario et al In the radioisotopic labeling assay, the K d values of fipronil binding to the GABARs of M. domestica were 24.3 and 23 nM, respectively. , Therefore, the superior affinity of fipronil for GABARs in M. domestica may underlie the high fipronil toxicity in insects. Moreover, the above results showed that fipronil exhibited high affinity for fish GABARs, which may be responsible for the high toxicity of fipronil to fish.…”

Section: Results and Discussionmentioning

confidence: 99%

Interactions of Fipronil within Fish and Insects: Experimental and Molecular Modeling Studies

Zhang

et al. 2018

J. Agric. Food Chem.

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Fipronil is an efficient phenylpyrazole insecticide that acts on insect γ-aminobutyric acid (GABA) receptors (GABARs) and has low toxicity to mammals but high toxicity to nontarget organisms such as fish. To develop novel efficient low-toxicity insecticides, it is necessary to determine the detailed toxic mechanism at the molecular target level. In this work, methods including affinity chromatography, fluorescent-labeled binding assays, and molecular modeling were integrated to explore the binding of fipronil to GABARs in fish ( Aristichthys nobilis) and insects ( Musca domestica). Affinity chromatography revealed that fipronil acts on two different subunits of GABARs in fish and M. domestica. Moreover, fluorescence assays revealed that fipronil exhibits similar affinity to the two GABARs. The K and B of fipronil binding to the A. nobilis GABAR were 346 ± 6 nmol/L and 40.6 ± 3.5 pmol/mg of protein, respectively. And the K and B of fipronil binding to the GABAR in M. domestica brain were 109 ± 9 nM and 21.3 ± 2.5 pmol/mg of protein, respectively. In addition, similar fipronil binding positions but different binding modes were observed in docking studies with Brachydanio rerio var. and M. domestica GABARs. These findings indicated similar interactions of fipronil with fish and insects, leading to high toxicity. The different binding features of fipronil between the two species might be helpful for the design and development of highly selective insecticides with low toxicity to fish.

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“…The potential exists for exploring such differences in the design of novel, safer pesticides. However, although some information has accumulated on GABA receptors of cockroach ( Periplaneta americana ) (Lummis & Sattelle, 1985; Sattelle et al , 1988), housefly ( Musca domestica ) (Abalis et al , 1985; Cohen & Casida, 1986) and fruit fly ( Drosophila melanogaster ) (Zhang et al , 1984; Rosario et al , 1989), to date there have been few studies on GABA receptors of insect pest species. Part of the reason for this is the lack of a suitable radioligand for these species.…”

Section: Introductionmentioning

confidence: 99%

Effects of [³H]‐BIDN, a novel bicyclic dinitrile radioligand for GABA‐gated chloride channels of insects and vertebrates

Rauh

Benner

Schnee

et al. 1997

British J Pharmacology

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3 Rat brain membranes were also shown to possess a population of saturable, speci®c [ 3 H]-BIDN binding sites, though of lower a nity than in rootworm and with a di erent pharmacological pro®le. Of the insecticidal GABAergic convulsants that displaced [ 3 H]-BIDN from rootworm, cockroach (Periplaneta americana) and rat brain membranes, many were more e ective in rootworm. 4 Functional GABA-gated chloride channels of rootworm nervous system and of cockroach nerve and muscle were blocked by BIDN, whereas cockroach neuronal GABA B receptors were una ected. 5 Expression in Xenopus oocytes of either rat brain mRNA, or cDNA-derived RNA encoding a GABA receptor subunit (Rdl) that is expressed widely in the nervous system of Drosophila melanogaster resulted in functional, homo-oligomeric GABA receptors that were blocked by BIDN. Thus, BIDN probes a novel site on GABA-gated Cl 7 channels to which a number of insecticidally-active molecules bind.

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Characterization of binding sites for [3H]Gaba in Drosophila melanogaster CNS membranes

Cited by 4 publications

References 20 publications

Agonist pharmacology of two Drosophila GABA receptor splice variants

Agonist pharmacology of two Drosophila GABA receptor splice variants

Interactions of Fipronil within Fish and Insects: Experimental and Molecular Modeling Studies

Effects of [³H]‐BIDN, a novel bicyclic dinitrile radioligand for GABA‐gated chloride channels of insects and vertebrates

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Characterization of binding sites for [3H]Gaba in Drosophila melanogaster CNS membranes

Cited by 4 publications

References 20 publications

Agonist pharmacology of two Drosophila GABA receptor splice variants

Agonist pharmacology of two Drosophila GABA receptor splice variants

Interactions of Fipronil within Fish and Insects: Experimental and Molecular Modeling Studies

Effects of [3H]‐BIDN, a novel bicyclic dinitrile radioligand for GABA‐gated chloride channels of insects and vertebrates

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Product

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Effects of [³H]‐BIDN, a novel bicyclic dinitrile radioligand for GABA‐gated chloride channels of insects and vertebrates