These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Absence of a protective effect of the oxime 2-PAM toward paraoxon-poisoned honey bees: acetylcholinesterase reactivation not at fault.
    Author: Polyzou A, Froment MT, Masson P, Belzunces LP.
    Journal: Toxicol Appl Pharmacol; 1998 Sep; 152(1):184-92. PubMed ID: 9772214.
    Abstract:
    We investigated the failure of 2-PAM to protect honey bees against poisoning with paraoxon. The protective effect of the oxime 2-PAM against inhibition of acetylcholinesterase (AChE) by paraoxon was estimated in vitro and in vivo and was correlated with the mortality of paraoxon-treated bees. In vitro, 2-PAM protected 90% of AChE activity in the presence of paraoxon and reactivated more than 90% of inhibited AChE. Minor soluble and major membrane-bound forms of bee AChE presented about similar extents of reactivation, but the first order rate constant of reactivation (kobs) of the soluble form is threefold higher than that of the membrane-bound form. However, this difference did not significantly influence the reactivation kinetics of total AChE; the constant kobs of the membrane-bound form reflected that of total AChE. The linear kinetic profile of total AChE reactivation supported the conclusion that there was a single population of reactivatable species. The bimolecular rate constant of reactivation (kr), the dephosphorylation rate constant (k2), and the dissociation constant (Kd) were 646 M-1.min-1, 0.84 min-1 and 1. 30 mM, respectively. In vivo, administration of 2-PAM, after paraoxon exposure, induced a complete protection of AChE activity, but did not elicit any significant effect on mortality in paraoxon-treated bees. The inefficiency of 2-PAM to antagonize paraoxon-induced mortality was not changed by the administration of 2-PAM in pretreatment-therapy and in therapy treatments. These results indicated that the mortality of paraoxon-poisoned honey bees was not due to a lack of AChE reactivation.
    [Abstract] [Full Text] [Related] [New Search]