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Interaction of organophosphate and carbamate cholinesterase inhibitors with acetylcholine binding proteins
Abstracts / Toxicology Letters 164S (2006) S1–S324
tion. It may be hypothesized that different mechanisms and/or transporters may be involved in PRX excretion. This research was supported in part by SERB laboratories (Paris, France).
S239
P17-13 Interaction of organophosphate and carbamate cholinesterase inhibitors with acetylcholine binding proteins
doi:10.1016/j.toxlet.2006.07.155
Zoran Radi´c, Todd T. Talley, Scott B. Hansen, Wenru Yu, Palmer Taylor
P17-12 The separate and combined action of Decis, Polyram and 2,4-D on the female rats reproductive system
University of California at San Diego, La Jolla, CA 92093, USA
N. Shepelskaya, M. Prodanchuk Medved’s Institute of Ecohygiene and Toxicology, Kiev, Ukraine On the basis of food pesticides residues monitoring results the plant protection substances, which most widely contaminate in agricultural commodities of Ukraine were identified. Experimental investigations of separate and combined action of this pesticides (Decis, Polyram and 2,4-D) on the female rat reproductive function were carried out. All studies were conducted using 500 Wistar rats (females and males). Pesticides were administered 5 days per week for 10 weeks, orally by gavage in the form of aqueous emulsions. After the scheduled period of exposure, treated females were paired with untreated males. The day on which evidence of mating was found was designated day zero of gestation. On days, 20 of gestation period females were sacrificed, and the number of corpuses luteum, of uterine implantation sites, resorptions, number of live and dead fetuses was recorded. The fetal body weights and the presence of visual developmental anomalies were recorded too. The reproductive performance of females was evaluated based on parameters as the reproductive cycle normality, precoital interval, fertility index, percentage mating, conception rate, gestation index, number of ovarian corpuses luteum, litter size, embryonic and fetal loss. Lowest-observed-adverse-effect levels (LOAEL) and no-observed-effect levels (NOEL) for reproductive toxicity under the conditions of separate exposure to examined pesticides were determined. Then the reproductive effects of a combination of this pesticides in the same doses and conditions were studied. Results of this experiments showed that lowest doses, which caused an adverse alteration under the conditions of separate exposure, did not affect adversely under three pesticides complex action. doi:10.1016/j.toxlet.2006.07.156
Acetylcholine binding proteins (AChBPs) are a family of invertebrate proteins that share significant structural similarity with nicotinic acetylcholine receptors (nAChRs). AChBPs assemble as stable homopentamers and display ligand recognition properties similar to those of the neuronal homopentameric a7 nAChR subtype. We have analyzed the interaction of recombinantly expressed and purified AChBPs from Lymnaea stagnalis, Aplysia californica and Bulinus Truncatus, with several organophosphate (OP) and carbamate (CB) cholinesterase inhibitors commonly used as pesticides or therapeutic agents. Binding of malathion, paraoxon, chlorpyrifos, chlorpyrifos oxon, echothiophate and eserine to AChBPs was measured from the concentration dependence of the pseudo-first order association rate, kobs , of the AChBP ligand gallamine on the OP or CB concentration. Rates were monitored in a millisecond time frame by stopped-flow measurements of intrinsic Trp fluorescence enhancement of AChBPs. The dissociation constant was determined from semi-logarithmic plots of kobs versus OP or CB concentrations and calculated by nonlinear regression. Up to millimolar malathion, paraoxon, chlorpyrifos and chlorpyrifos oxon did not show noticeable binding to AChBPs, in the absence or presence of an agonist acetylthiocholine. Eserine and echothiophate, however, bound reversibly to AChBPs at high nanomolar and low micromolar concentrations, respectively. Organophosphates have been known to reversibly interact with several types of neuronal nAChRs, suggesting the possibility of their involvement in the mechanisms of toxicity in prolonged exposure to OP and CB compounds. doi:10.1016/j.toxlet.2006.07.157
tion. It may be hypothesized that different mechanisms and/or transporters may be involved in PRX excretion. This research was supported in part by SERB laboratories (Paris, France).
S239
P17-13 Interaction of organophosphate and carbamate cholinesterase inhibitors with acetylcholine binding proteins
doi:10.1016/j.toxlet.2006.07.155
Zoran Radi´c, Todd T. Talley, Scott B. Hansen, Wenru Yu, Palmer Taylor
P17-12 The separate and combined action of Decis, Polyram and 2,4-D on the female rats reproductive system
University of California at San Diego, La Jolla, CA 92093, USA
N. Shepelskaya, M. Prodanchuk Medved’s Institute of Ecohygiene and Toxicology, Kiev, Ukraine On the basis of food pesticides residues monitoring results the plant protection substances, which most widely contaminate in agricultural commodities of Ukraine were identified. Experimental investigations of separate and combined action of this pesticides (Decis, Polyram and 2,4-D) on the female rat reproductive function were carried out. All studies were conducted using 500 Wistar rats (females and males). Pesticides were administered 5 days per week for 10 weeks, orally by gavage in the form of aqueous emulsions. After the scheduled period of exposure, treated females were paired with untreated males. The day on which evidence of mating was found was designated day zero of gestation. On days, 20 of gestation period females were sacrificed, and the number of corpuses luteum, of uterine implantation sites, resorptions, number of live and dead fetuses was recorded. The fetal body weights and the presence of visual developmental anomalies were recorded too. The reproductive performance of females was evaluated based on parameters as the reproductive cycle normality, precoital interval, fertility index, percentage mating, conception rate, gestation index, number of ovarian corpuses luteum, litter size, embryonic and fetal loss. Lowest-observed-adverse-effect levels (LOAEL) and no-observed-effect levels (NOEL) for reproductive toxicity under the conditions of separate exposure to examined pesticides were determined. Then the reproductive effects of a combination of this pesticides in the same doses and conditions were studied. Results of this experiments showed that lowest doses, which caused an adverse alteration under the conditions of separate exposure, did not affect adversely under three pesticides complex action. doi:10.1016/j.toxlet.2006.07.156
Acetylcholine binding proteins (AChBPs) are a family of invertebrate proteins that share significant structural similarity with nicotinic acetylcholine receptors (nAChRs). AChBPs assemble as stable homopentamers and display ligand recognition properties similar to those of the neuronal homopentameric a7 nAChR subtype. We have analyzed the interaction of recombinantly expressed and purified AChBPs from Lymnaea stagnalis, Aplysia californica and Bulinus Truncatus, with several organophosphate (OP) and carbamate (CB) cholinesterase inhibitors commonly used as pesticides or therapeutic agents. Binding of malathion, paraoxon, chlorpyrifos, chlorpyrifos oxon, echothiophate and eserine to AChBPs was measured from the concentration dependence of the pseudo-first order association rate, kobs , of the AChBP ligand gallamine on the OP or CB concentration. Rates were monitored in a millisecond time frame by stopped-flow measurements of intrinsic Trp fluorescence enhancement of AChBPs. The dissociation constant was determined from semi-logarithmic plots of kobs versus OP or CB concentrations and calculated by nonlinear regression. Up to millimolar malathion, paraoxon, chlorpyrifos and chlorpyrifos oxon did not show noticeable binding to AChBPs, in the absence or presence of an agonist acetylthiocholine. Eserine and echothiophate, however, bound reversibly to AChBPs at high nanomolar and low micromolar concentrations, respectively. Organophosphates have been known to reversibly interact with several types of neuronal nAChRs, suggesting the possibility of their involvement in the mechanisms of toxicity in prolonged exposure to OP and CB compounds. doi:10.1016/j.toxlet.2006.07.157