Structure-toxicity analysis of Type-2 Alkenes

In vitro neurotoxicity

Richard M. LoPachin, David S. Barber, Brian C. Geohagen, Terrence Gavin, Deke He, Soma Das

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Acrylamide (ACR) is a conjugated type-2 alkene that produces synaptic toxicity presumably by sulfhydryl adduction. The α,β-unsaturated carbonyl of ACR is a soft electrophile and, therefore, adduction of nucleophilic thiol groups could occur through a conjugate (Michael) addition reaction. To address the mechanism of thiol adduct formation and corresponding neurotoxicological importance, we defined structure-toxicity relationships among a series of conjugated type-2 alkenes (1μM-10mM), which included acrolein and methylvinyl ketone. Results show that exposure of rat striatal synaptosomes to these chemicals produced parallel, concentration-dependent neurotoxic effects that were correlated to loss of free sulfhydryl groups. Although differences in relative potency were evident, all conjugated analogs tested were equiefficacious with respect to maximal neurotoxicity achieved. In contrast, nonconjugated alkene or aldehyde congeners did not cause synaptosomal dysfunction or sulfhydryl loss. Acrolein and other α,β-unsaturated carbonyls are bifunctional (electrophilic reactivity at the C-1 and C-3 positions) and could produce in vitro neurotoxicity by forming protein cross-links rather than thiol monoadducts. Immunoblot analysis detected slower migrating, presumably derivatized, synaptosomal proteins only at very high acrolein concentrations (≥ 25mM). Exposure of synaptosomes to high concentrations of ACR (1M), N-ethylmaleimide (10mM), and methyl vinyl ketone (MVK) (100mM) did not alter the gel migration of synaptosomal proteins. Furthermore, hydralazine (1mM), which blocks the formation of protein cross-links, did not affect in vitro acrolein neurotoxicity. Thus, type-2-conjugated alkenes produced synaptosomal toxicity that was linked to a loss of thiol content. This is consistent with our hypothesis that the mechanism of ACR neurotoxicity involves formation of Michael adducts with protein sulfhydryl groups.

Original languageEnglish (US)
Pages (from-to)136-146
Number of pages11
JournalToxicological Sciences
Volume95
Issue number1
DOIs
StatePublished - Jan 2007

Fingerprint

Acrolein
Acrylamide
Alkenes
Sulfhydryl Compounds
Toxicity
Synaptosomes
Proteins
Corpus Striatum
Hydralazine
Ethylmaleimide
Addition reactions
Aldehydes
Gels
Rats
In Vitro Techniques
link protein
3-buten-2-one

Keywords

  • Acrolein
  • Acrylamide
  • Adduct formation
  • Distal axonopathy
  • Neurodegeneration
  • Synapse

ASJC Scopus subject areas

  • Toxicology

Cite this

Structure-toxicity analysis of Type-2 Alkenes : In vitro neurotoxicity. / LoPachin, Richard M.; Barber, David S.; Geohagen, Brian C.; Gavin, Terrence; He, Deke; Das, Soma.

In: Toxicological Sciences, Vol. 95, No. 1, 01.2007, p. 136-146.

Research output: Contribution to journalArticle

LoPachin, RM, Barber, DS, Geohagen, BC, Gavin, T, He, D & Das, S 2007, 'Structure-toxicity analysis of Type-2 Alkenes: In vitro neurotoxicity', Toxicological Sciences, vol. 95, no. 1, pp. 136-146. https://doi.org/10.1093/toxsci/kfl127
LoPachin, Richard M. ; Barber, David S. ; Geohagen, Brian C. ; Gavin, Terrence ; He, Deke ; Das, Soma. / Structure-toxicity analysis of Type-2 Alkenes : In vitro neurotoxicity. In: Toxicological Sciences. 2007 ; Vol. 95, No. 1. pp. 136-146.
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