Glufosinate aerogenic exposure induces glutamate and IL-1 receptor dependent lung inflammation

Developmental synapse pathology triggered by maternal exposure to the herbicide glufosinate ammonium

Environmental and genetic factors influence synapse formation. Numerous animal experiments have revealed that pesticides, including herbicides, can disturb normal intracellular signals, gene expression, and individual animal behaviors. However, the mechanism underlying the adverse outcomes of pesticide exposure remains elusive. Herein, we investigated the effect of maternal exposure to the herbicide glufosinate ammonium (GLA) on offspring neuronal synapse formation in vitro. Cultured cerebral cortical neurons prepared from mouse embryos with maternal GLA exposure demonstrated impaired synapse formation induced by synaptic organizer neuroligin 1 (NLGN1)-coated beads. Conversely, the direct administration of GLA to the neuronal cultures exhibited negligible effect on the NLGN1-induced synapse formation. The comparison of the transcriptomes of cultured neurons from embryos treated with maternal GLA or vehicle and a subsequent bioinformatics analysis of differentially expressed genes (DEGs) identified "nervous system development," including "synapse," as the top-ranking process for downregulated DEGs in the GLA group. In addition, we detected lower densities of parvalbumin (Pvalb)-positive neurons at the postnatal developmental stage in the medial prefrontal cortex (mPFC) of offspring born to GLA-exposed dams. These results suggest that maternal GLA exposure induces synapse pathology, with alterations in the expression of genes that regulate synaptic development via an indirect pathway distinct from the effect of direct GLA action on neurons.

Prognostic value of neutrophil to lymphocyte ratio in the diagnosis of neurotoxicity after glufosinate ammonium poisoning

Neurotoxicity related to glufosinate ammonium is known to occur after a latent period of 4-60 hr following ingestion of this herbicide. However, neurotoxicity is difficult to predict in the emergency department (ED) and only a few parameters are known to be useful to indicate development of neurotoxicity. Determination of a systemic inflammation parameter such as the neutrophil to lymphocyte ratio (NLR), is a rapid and simple method which was found to be a prognostic marker in various clinical conditions such as sepsis, cardiac disorders, stroke, and cancer. Therefore, the aim of this study was to determine whether the NLR might predict neurotoxicity and be used at ED to detect neurotoxicity induced following glufosinate ammonium poisoning in admitted patients. This retrospective observational study collected data from consecutive patients diagnosed with acute glufosinate ammonium poisoning between January 2005 and December 2020. The primary outcome was development of neurotoxicity following acute glufosinate ammonium poisoning. Out of the 72 patients selected 44 patients (61.1%) exhibited neurotoxic symptoms. Neurotoxicity appeared with an approximate latent period of 12 hr. The NLR was significantly higher in the group displaying neurotoxicity. Multivariable analysis showed that the NLR was significant in predicting neurotoxicity. The NLR was independently associated with neurotoxicity initiated by glufosinate ammonium. Therefore, the use of the NLR might help clinically to readily and rapidly predict development of neurotoxicity associated with glufosinate ammonium at the ED.

Prenatal exposure to glufosinate ammonium disturbs gut microbiome and induces behavioral abnormalities in mice

Glufosinate ammonium (GLA) is a widely used organophosphate herbicide, which could be commonly detected in body fluids of both pregnant women and newborns. Existing evidences indicate that GLA has reproductive toxicity, while data concerning the effects of prenatal GLA exposure on neurodevelopment is rather limited. Here we employed a mouse model exposed to GLA prenatally. Reduced locomotor activity, impaired memory formation and autism-like behaviors were observed in the treatment group. Marked alteration in gut microbiome of the treatment offspring mice could be found at 4th week, and seemed to recover over time. Fecal metabolomics analysis indicated remarkable changes in microbiome-related metabolism in the treatment group, which could be the cause of behavioral abnormality in mice. Present study suggested that prenatal exposure to GLA disturbed gut microbiome and metabolism, and thereby induced behavioral abnormalities in mice.

Reduction in Blood Glutamate Levels Combined With the Genetic Inactivation of A2AR Significantly Alleviate Traumatic Brain Injury-Induced Acute Lung Injury

Traumatic brain injury-induced acute lung injury (TBI-ALI) is a serious complication of traumatic brain injury (TBI). Our previous clinical study found that high levels of blood glutamate after TBI were closely related to the occurrence and severity of TBI-ALI, while it remains unknown whether a high concentration of blood glutamate directly causes or aggravates TBI-ALI. We found that inhibition of the adenosine A2A receptor (A2AR) after brain injury alleviated the TBI-ALI; however, it is unknown whether lowering blood glutamate levels in combination with inhibiting the A2AR would lead to better effects. Using mouse models of moderate and severe TBI, we found that intravenous administration of L-glutamate greatly increased the lung water content, lung-body index, level of inflammatory markers in bronchoalveolar lavage fluid and acute lung injury score and significantly decreased the PaO2/FiO2 ratio. Moreover, the incidence of TBI-ALI and the mortality rate were significantly increased, and the combined administration of A2AR activator and exogenous glutamate further exacerbated the above damaging effects. Conversely, lowering the blood glutamate level through peritoneal dialysis or intravenous administration of oxaloacetate notably improved the above parameters, and a further improvement was seen with concurrent A2AR genetic inactivation. These data suggest that A2AR activation aggravates the damaging effect of high blood glutamate concentrations on the lung and that combined treatment targeting both A2AR and blood glutamate may be an effective way to prevent and treat TBI-ALI.

Acute glufosinate-based herbicide treatment in rats leads to increased ocular interleukin-1β and c-Fos protein levels, as well as intraocular pressure

Glufosinate is a common herbicide with neurotoxic effects, leading to seizures, convulsions and memory loss. Glufosinate indirectly induces glutamate toxicity by inhibiting glutamine synthesis in astrocytes. Here, we studied the acute toxic effects of a glufosinate-based herbicide in rat optic nerve at three doses (40, 80 or 120 μM, equal to 714 or 21 mg/kg bw/day). Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, glucose, calcium, as well as creatinine concentrations were analyzed after 24, 48 and 72 h treatment. Intraocular pressure (IOP) (expressed as the average of both eyes) was measured with a rebound tonometer. Interleukin-1β (IL-1β) and c-Fos expression were determined by immunohistochemistry. The results established that the glufosinate-based herbicide significantly increased IL-1β and c-Fos immunopositivity in the optic nerve (p < 0.05), concomitant with increased IOP. These results suggest that commercial formulations of glufosinate acutely affect the optic nerve.

Perinatal Exposure to the Cyanotoxin β-N-Méthylamino-L-Alanine (BMAA) Results in Long-Lasting Behavioral Changes in Offspring-Potential Involvement of DNA Damage and Oxidative Stress

We recently demonstrated that perinatal exposure to the glutamate-related herbicide, glufosinate ammonium, has deleterious effects on neural stem cell (NSC) homeostasis within the sub-ventricular zone (SVZ), probably leading to ASD-like symptoms in offspring later in life. In the present study, we aimed to investigate whether perinatal exposure to another glutamate-related toxicant, the cyanobacterial amino acid β-N-methylamino-L-alanine (BMAA), might also trigger neurodevelopmental disturbances. With this aim, female mice were intranasally exposed to low doses of BMAA, 50 mg kg^-1 three times a week from embryonic days 7-10 to postnatal day 21. Behavioral analyses were performed during the offspring's early life and during adulthood. Developmental analyses revealed that perinatal exposure to BMAA hastened the appearance of some reflexes and communicative skills. BMAA-exposed offspring displayed sex-dependent changes in emotional cognition shortly after exposure. Later in life, the female offspring continued to express emotional defects and to display abnormal sociability, while males were less affected. To assess whether early exposure to BMAA had deleterious effects on NSC homeostasis, we exposed mice NSCs to 1 and 3 mM BMAA during 24 h. We found that BMAA-exposed NSCs produced high levels of ROS, highlighting the ability of BMAA to induce oxidative stress. We also showed that BMAA exposure increased the number of γH2AX/53BP1 foci per nucleus, suggesting that BMAA-induced DNA damage in NSCs. Collectively, this data strongly suggests that perinatal exposure to the cyanobacteria BMAA, even at low doses, results in neurobehavioral disturbances during both the postnatal period and adulthood. This is considered to be underpinned at the cellular level through dysregulation of NSC homeostasis in the developing brain.

Dramatic increases in blood glutamate concentrations are closely related to traumatic brain injury-induced acute lung injury

Traumatic brain injury-induced acute lung injury (TBI-ALI) is a serious complication after brain injury for which predictive factors are lacking. In this study, we found significantly elevated blood glutamate concentrations in patients with TBI or multiple peripheral trauma (MPT), and patients with more severe injuries showed higher blood glutamate concentrations and longer durations of elevated levels. Although the increase in amplitude was similar between the two groups, the duration was longer in the patients with TBI. There were no significant differences in blood glutamate concentrations in the patients with MPT with regard to ALI status, but the blood glutamate levels were significantly higher in the patients with TBI-ALI than in those without ALI. Moreover, compared to patients without ALI, patients with TBI showed a clearly enhanced inflammatory response that was closely correlated with the blood glutamate levels. The blood glutamate concentration was also found to be a risk factor (adjusted odds ratio, 2.229; 95% CI, 1.082–2.634) and was a better predictor of TBI-ALI than the Glasgow Coma Scale (GCS) score. These results indicated that dramatically increased blood glutamate concentrations were closely related to the occurrence of TBI-ALI and could be used as a predictive marker for “at-risk” patients.