Aminomethylphosphonic acid (AMPA), a glyphosate metabolite, decreases
plasma cholinesterase activity in rats
Abstract
Glyphosate, a widely used herbicide, is linked to a plethora of
deleterious effects in both clinical and preclinical studies.
Nevertheless, the effects of its main metabolite, aminomethylphosphonic
acid (AMPA), whose half-life in soil is even longer than that of
glyphosate, have been little explored. On this basis, as a first
approach, in this work we report that intraperitoneal (i.p.)
administration of AMPA or glyphosate (at 10, 56, and 100 mg/kg)
decreased, to a similar extent, plasma cholinesterase (ChE) activity in
acutely exposed rats. Moreover, we designed an experimental protocol to
analyze and compare the effects of AMPA and glyphosate on human plasma
ChE activity; this protocol consisted of adding these compounds to human
plasma to subsequently test the effects of this plasma on the
contraction to acetylcholine (ACh) in the frog rectus abdominis muscle
(an indirect estimate of ChE activity). Accordingly, this muscular
contraction to ACh was evaluated before and after pre‑incubation of ACh
with: (i) plasma alone; (ii) plasma with AMPA; and (iii) plasma with
glyphosate. Our results indicate that AMPA, like glyphosate, decreased
ChE activity in the plasma of rats (when given i.p.) and humans (when
added in vitro), suggesting that both xenobiotics may exert
similar toxicological effects.