Acute glyphosate and aminomethylphosphonic acid (AMPA), its major metabolite, impaired spatial orientation, navigation, learning and/or memory in female rats

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Human exposure to glyphosate-based herbicides (GBH) has been associated with a range of toxicological effects involving the central nervous system (CNS) such as alterations in learning and memory. Nevertheless, the effects of aminomethylphosphonic acid (AMPA), the main metabolite of glyphosate, remain essentially obscure. Previous preclinical reports suggest that acute intoxication with AMPA and glyphosate exerts decrease on hippocampal acetylcholinesterase activity and produces more metabolomic alterations in the female brain over the male one. Therefore, this work explored the effects of acute AMPA and glyphosate on spatial learning, memory and navigation in female rats. Sprague Dawley rats received a single injection (i.p.) of: (i) vehicle; (ii) 10 or 100mg/kg of AMPA; or (iii) 10 or 100mg/kg of glyphosate; subsequently, the Barnes maze paradigm was performance. Animals from the control group decreased latency and the attempts to solve the Barnes maze; and increased the degree of orientation when compared first training sessions (S1) vs. the last one (S4; p < 0.05). In contrast, both 10 and 100mg/kg of glyphosate and 100mg/kg of AMPA prevented the decrease in latency and attempts; and the increase of orientation (p>0.05 S1 vs. S4). Both treatments decreased the use of the spatial navigation strategy (p < 0.05). Besides, glyphosate at the higher dose but not AMPA impaired the spatial memory during the test. Our findings suggest that acute exposure to glyphosate and AMPA similarly affected spatial orientation, navigations, learning and/or memory.