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.

The fungicide Imazalil (IMZ) is widely used to maintain the freshness of fruits and vegetables after harvest. Despite its widespread use, the neurotoxic effects of IMZ remain poorly studied. Thus, in this work, we aimed to investigate the effects of subacute IMZ exposure on memory and learning, as well as on cholinesterase (ChE) activity, in orally exposed rats. To do so, Wistar rats were exposed to doses corresponding to 1/8, 1/4, and 1/2 of the LD50 of IMZ. Each dose was divided into four equal parts and administered once daily for four consecutive days, while behavioral performance was assessed using the Barnes Maze. On day 5, we measured ChE activity in the hippocampus and serum. The enzymatic activity assays demonstrated a dose-dependent decrease in both cholinesterase activities at 1/4 LD50 of IMZ. In addition, rats in the control group exhibited a typical learning curve in the Barnes maze, characterized by reduced latency and fewer attempts to locate the escape box from the first session (S1) to the final session (S4). The typical learning curve was prevented by a 1/4 LD50 treatment. Additionally, this dose prevented an increase in spatial navigation strategy use, observed in the control group (S1 vs. S4). To our knowledge, these results proved that IMZ inhibits in vivo the activity of both brain and serum ChEs, and exhibits evidence of learning and memory impairments, suggesting that IMZ has neurotoxic effects in rats, probably mediated by alterations in the cholinergic system.

Cafeteria diet, rich in fat and sugar, rapidly induces metabolic dysfunction and alters central energy regulation. We examined behavior and hypothalamic protein abundance profiles in cafeteria-diet-fed rats classified into weight-gain quartiles (Q1–Q4) and compared with standard-chow-fed controls. Pre-adolescent male Sprague–Dawley rats (n = 39:10 controls; Q1–Q4, n = 7–8 each) received ad libitum access to standard chow or a palatable cafeteria diet and underwent open field testing followed by quantitative LC–MS/MS proteomics of the hypothalamus. Behavioral assessment showed no major differences in locomotion, anxiety-like parameters, or exploration, except for reduced grooming (p ≤ 0.05) in cafeteria-fed versus control animals. Global, threshold-independent analyses showed that the lower-weight-gain phenotype (Q1) was significantly more distant from controls than the higher-weight-gain phenotype (Q4) (multivariate distance to the control centroid; Mann–Whitney U, p = 0.006), a pattern also observed by principal component analysis and hierarchical clustering. Consistently, of 17 proteins that remained significant after false discovery rate correction, 16 differed between Q1 and control and only one between Q4 and control, despite both phenotypes having ad libitum access to the same cafeteria diet. These findings suggest that lower weight gain is associated with more extensive hypothalamic protein abundance changes, although a causal link remains to be established, and they highlight candidate pathways for future mechanistic studies.