Protective role of zeaxanthin on acrylamide-induced neurotoxicity in Wistar rats.

To investigate the effect of hydrogen gas on NOD-like receptor protein 3 (NLRP3) inflammasomes in the cerebral cortex of rats with traumatic brain injury (TBI). 120 adult male Sprague-Dawley (SD) rates were randomly divided into 5 groups (n = 24): sham operation group (S group), TBI model group (T group), TBI+NLRP3 inhibitor MCC950 group (T+M group), TBI+hydrogen gas group (T+H group), TBI+hydrogen gas+MCC950 group (T+H+M group). TBI model was established by controlled cortical impact. NLRP3 inhibitor MCC950 (10 mg/kg) was intraperitoneally injected for 14 consecutive days before TBI operation in T+M and T+H+M groups. 2% hydrogen inhalation was given for 1 hour at 1 hour and 3 hours after TBI operation in T+H and T+H+M groups. At 6 hours after TBI operation, the pericontusional cortex tissues were obtained, the content of Evans blue (EB) was detected to evaluate the permeability of the blood-brain barrier. Water content in brain tissue was detected. The cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL) and the neuronal apoptosis index was calculated. The expressions of Bcl-2, Bax, NLRP3, apoptosis-associated speck-like protein containing CARD (ASC) and caspase-1 p20 were detected by Western blotting. The levels of interleukins (IL-1β, IL-18) were detected by enzyme-linked immunosorbent assay (ELISA). Compared with the S group, the content of EB in cerebral cortex, water content in brain tissue, apoptosis index and the expressions of Bax, NLRP3, ASC, caspase-1 p20 in T group were significantly increased, the expression of Bcl-2 was down-regulated, the levels of IL-1β and IL-18 were increased [the content of EB (μg/g): 87.57±6.89 vs. 10.54±1.15, water content in brain tissues: (83.79±2.74)% vs. (74.50±1.19)%, apoptotic index: (62.66±5.33)% vs. (4.61±0.96)%, Bax/β-actin: 4.20±0.44 vs. 1, NLRP3/β-actin: 3.55±0.31 vs. 1, ASC/β-actin: 3.10±0.26 vs. 1, caspase-1 p20/β-actin: 3.28±0.24 vs. 1, Bcl-2/β-actin: 0.23±0.03 vs. 1, IL-1β (ng/g): 221.58±19.15 vs. 27.15±3.27, IL-18 (ng/g): 87.26±7.17 vs. 12.10±1.85, all P < 0.05]. Compared with the T group, the T+M, T+H and T+H+M groups had significant reductions in the content of EB and water content in brain tissue, apoptotic index of the cerebral cortex, the expressions of Bax, NLRP3, and caspase-1 p20 in the brain tissue and the levels of IL-1β and IL-18, significant increases in the expression of Bcl-2. However, there was no significant difference in ASC expression. Compared with the T+H group, the content of EB in the cerebral cortex, water content in brain tissue, and apoptotic index, and the expressions of Bax, NLRP3 and caspase-1 p20 were further down-regulated in T+H+M group, the expression of Bcl-2 was further up-regulated, the levels of IL-1β and IL-18 were further decreased [the content of EB (μg/g): 40.49±3.15 vs. 51.96±4.69, water content in brain tissue: (76.58±1.04)% vs. (78.76±1.16)%, apoptotic index: (32.22±3.44)% vs. (38.54±3.89)%, Bax/β-actin: 1.92±0.16 vs. 2.56±0.21, NLRP3/β-actin: 1.94±0.14 vs. 2.37±0.24, caspase-1 p20/β-actin: 1.97±0.17 vs. 2.31±0.19, Bcl-2/β-actin: 0.82±0.07 vs. 0.52±0.04, IL-1β (ng/g): 86.23±7.09 vs. 110.44±10.48, IL-18 (ng/g): 40.18±3.22 vs. 46.23±4.02, all P < 0.05], but there were no statistical significance in all the indicators between T+M group and T+H group. The mechanism by which hydrogen gas alleviates TBI may be related to inhibiting NLRP3 inflammasomes in the cerebral cortex of rats.

Background: Neurotoxicity is one of the most recognized effects of acrylamide (ACR) in humans and animals. Oxidative stress is an important mechanism in ACR-induced neurotoxicity. Objectives: In this research, the effect of silymarin as a potent antioxidant was evaluated against ACR-induced toxicity in both in vitro and in vivo models. Methods: For the in vitro assay, PC12 cells were exposed to different concentrations (2.5 - 100 µM) of silymarin for 24 hours. ACR at a final concentration of 5 mM was added and cell viability was determined using the MTT assay. For the in vivo study, neurotoxicity was induced using intraperitoneal (IP) administration of ACR (50 mg/kg) for 11 days. The effects of different doses of silymarin (40, 80, and 160 mg/kg IP, respectively) were evaluated in ACR-induced neurotoxicity in Wistar rats based on gait scores. Results: Exposure to ACR reduced cell viability in PC12 cells. Pre-treatment of cells with silymarin (100 µM) significantly reduced ACR-induced toxicity. In addition, administration of ACR induced severe toxicity in Wistar rats, while silymarin at a dose of 160 mg/kg could improve the rats’ gait abnormalities. Conclusions: With regard to the potent antioxidant properties of silymarin, the neuroprotective effects of this natural compound suggested in the current study may in part be mediated through inhibition of oxidative stress.

Acrylamide (ACR) is a toxic agent for humans and animals. Gentisic acid, anaspirinmetabolite, has antioxidant activity. Therefore, the present study investigated the probable protective effects of aspirin and gentisic acid on ACR-induced neurotoxicity in PC12 cells and rats. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the effects of aspirin and gentisic acid (1.25, 2.5, 5 µM) on ACR (5 mM) toxicity. Male Wistar rats were randomly divided into 13 groups: (1) Control group, (2) ACR (50 mg/kg, 11 days, i.p.), (3-5) ACR + aspirin (25, 50, 75 mg/kg, 11 days, p.o.), (6-8) ACR + gentisic acid (25, 50, 75 mg/kg, 11 days, p.o.), (9) ACR + vitamin E (200 mg/kg, every other day, i.p.), (10, 11) Aspirin (75, 100 mg/kg, 11 days, p.o.), (12, 13) Gentisic acid (75, 100 mg/kg, 11 days, p.o.). Behavioral tests were assessed on the final day of the study. In the cerebral cortex, malondialdehyde (MDA), glutathione (GSH), cleaved-caspase-3, and microtubule-associated protein 1A/1B-light chain 3 (LC3) protein levels were evaluated. When compared with the ACR group, aspirin (2.5, 5 µM) and gentisic acid (2.5 µM) significantly enhanced cell viability. In comparison to the control group, ACR induced severe motor impairment, elevated MDA, cleaved-caspase-3, LC3 II/I ratio, and decreased GSH levels in the cerebral cortex of rats. ACR-induced changes were significantly reversed by aspirin and gentisic acid (25 mg/kg). Oxidative stress, apoptosis, and autophagy play important roles in the neurotoxicity of ACR. Aspirin and gentisic acid significantly reduced ACR-induced toxicity by inhibiting the mentioned mechanisms.

Acrylamide is an environmental electrophile that has been produced in large amounts for many years. There is concern about the adverse health effects of acrylamide exposure due to its widespread industrial use and also presence in commonly consumed foods and others. IL-1β is a key cytokine that protects the brain from inflammatory insults, but its role in acrylamide-induced neurotoxicity remains unknown. We reported recently that deletion of IL-1β gene exacerbates ACR-induced neurotoxicity in mice. The aim of this study was to identify genes or signaling pathway(s) involved in enhancement of ACR-induced neurotoxicity by IL-1β gene deletion or ACR-induced neurotoxicity to generate a hypothesis mechanism explaining ACR-induced neurotoxicity. C57BL/6J wild-type and IL-1β KO mice were exposed to ACR at 0, 12.5, 25mg/kg by oral gavage for 7days/week for 4weeks, followed by extraction of mRNA from mice cerebral cortex for RNA sequence analysis. IL-1β deletion altered the expression of genes involved in extracellular region, including upregulation of PFN1 gene related to amyotrophic lateral sclerosis and increased the expression of the opposite strand of IL-1β. Acrylamide exposure enhanced mitochondria oxidative phosphorylation, synapse and ribosome pathways, and activated various pathways of different neurodegenerative diseases, such as Alzheimer disease, Parkinson disease, Huntington disease, and prion disease. Protein network analysis suggested the involvement of different proteins in related to learning and cognitive function, such as Egr1, Egr2, Fos, Nr4a1, and Btg2. Our results identified possible pathways involved in IL-1β deletion-potentiated and ACR-induced neurotoxicity in mice.

Objective(s):Acrylamide (ACR) has broad applications in different industries. It also forms in food during heating process. Oxidative stress has a critical role in ACR-induced neurotoxicity in both in vitro and in vivo models; therefore, the aim of the current study was the evaluation of effects of thymoquinone, the main constituent of volatile oil from Nigella sativa seeds in ACR-induced neurotoxicity.Materials and Methods:Male Wistar rats were treated with ACR (50 mg/kg IP) alone or with thymoquinone (TQ) (2.5, 5, 10 mg/kg IP) for 11 days. Two protocols were used in this study, A: in this one TQ and ACR were used simultaneously, B: Administration of TQ was started 1 week before ACR treatment and continued during exposure to ACR. At the end of the treatment, behavioral index (gait score) was examined for rats. After that, rats were sacrificed and molondialdehyde (MDA) as a marker of lipid peroxidation and glutathione (GSH) content were determined in cerebral cortex.Results:Exposure to ACR led to severe gait abnormalities and treatment with TQ significantly decreased abnormalities. Level of MDA was elevated in cerebral cortex after exposure to ACR while TQ treatment significantly and in a dose-dependent manner reduced lipid peroxidation. Results clearly showed that there is no significant difference between two protocols of administration of TQ.Conclusion:It suggests the neuroprotective effect of TQ in this model in part, may be because of due the antioxidant activity of this natural compound.

Objective(s):Acrylamide (ACR) has many applications in different industries. ACR damages the central and the peripheral nervous system in human and animals. Importance of ACR-induced neurotoxicity encouraged researchers to find both different mechanisms involved in ACR neurotoxicity and potent neuroprotective agents. Therefore, this study was designed to investigate the protective effect of crocin, an active constituent of Crocus sativus L. (saffron) on ACR-induced neurotoxicity in Wistar rats.Materials and Methods:Animals were treated with ACR (50 mg/kg, IP) 11 days for induction neurotoxicity. Crocin (12.5, 25 and 50 mg/kg, IP) were used during treatment with ACR. At the end of treatment, gait score examination was performed. Then, rats were sacrificed and the severity of damage in brain tissue was determined using pathological tests. The level of malondialdehyde (MDA) and glutathione (GSH) content were evaluated in cerebral cortex and cerebellum to determine the role of oxidative stress in this model.Results:Exposure to ACR induced severe gait abnormalities and pathological changes, but administration of crocin markedly improved behavioral index and histopathological damages. The elevation of lipid peroxidation parallel with reduction of GSH level was observed in cerebral cortex and cerebellum following exposure to ACR. Treatment with crocin markedly decreased MDA level, while elevated GSH content in nervous system as compared to ACR-treated animals.Conclusion:The administration of crocin markedly improved behavioral and histopathological damages in Wistar rats exposed to ACR. Reduction of oxidative stress can be considered as an important mechanism of neuroprotective effects of crocin against ACR-induced toxicity.

The role of sulfur-containing drugs, disulfiram (DSF) and N-acetylcysteine (NAC), in alleviating neuroinflammation is poorly understood. The objective of this study was to examine the effect of DSF and NAC on memory and on the metabolism of L-cysteine and inflammation-related parameters in the cerebral cortex of rats in a model of neuroinflammation induced by the administration of lipopolysaccharide (LPS). All the treatments were administered intraperitoneally for 10 days (LPS at a dose of 0.5 mg/kg b.w., DSF at a dose of 100 mg/kg b.w, and NAC at a dose of 100 mg/kg b.w.). Behavior was evaluated by the novel object recognition (NOR) test and object location (OL) test, and the level of brain-derived neurotrophic factor (BDNF) was assayed to evaluate neuronal functioning. Cerebral cortex homogenates were tested for hydrogen sulfide (H2S), sulfane sulfur, sulfates, non-protein sulfhydryl groups (NPSH), nitric oxide (NO), and reactive oxygen species (ROS) by biochemical analysis. Neither DSF nor NAC alleviated LPS-induced memory disorders estimated by the NOR test and OL test. The studied compounds also did not affect significantly the levels of BDNF, ROS, NO, H2S, and sulfane sulfur in the cerebral cortex. However, we observed an increase in sulfate concentration in brain tissues after LPS treatment, while DSF and NAC caused an additional increase in sulfate concentration. On the other hand, our study showed that the administration of DSF or NAC together with LPS significantly enhanced the cortical level of NPSH, of which glutathione is the main component. Our study did not confirm the suggested potential of DSF and NAC to correct memory disorders; however, it corroborated the notion that they reduced oxidative stress induced by LPS by increasing the NPSH level. Additionally, our study showed an increase in sulfate concentration in the brain tissues after LPS treatment, which means the upregulation of sulfite and sulfate production in inflammatory conditions.

Oxidative stress is a key pathogenic factor in both neurogenerative and metabolic diseases. However, its contribution in the brain complications of insulin resistance is still not well understood. Therefore, the aim of this study was the evaluation of redox homeostasis and oxidative damage in the hypothalamus and cerebral cortex of insulin-resistant and control rats. 16 male Wistar rats were divided into two equal groups (n = 8): the control and high fat diet group (HFD). Prooxidant enzymes (xanthine oxidase and NADPH oxidase); enzymatic and nonenzymatic antioxidants [glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase-1 (SOD-1), and uric acid (UA)]; and oxidative damage products [advanced glycation end products (AGE), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), and 8-hydroxy-2′-deoxyguanosine (8-OHdG)] as well as the total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), and total ferric reducing ability of sample (FRAP) were evaluated in the hypothalamus and cerebral cortex as well as serum/plasma of HFD-fed and control rats. The activity of prooxidant enzymes was significantly increased in the cerebral cortex and hypothalamus of HFD-fed rats vs. control rats. Additionally, we have showed enhanced antioxidant efficiency in the hypothalamus (↑CAT, ↑UA, ↑TAC, and ↑FRAP) and cerebral cortex (↑GPx, ↑CAT, ↑SOD-1, ↑UA, ↑TAC, and ↑FRAP) of HFD-fed rats. All of the oxidative damage markers (AGE, 4-HNE, MDA, 8-OHdG, and OSI) were significantly increased in the cerebral cortex of insulin-resistant rats, while only 4-HNE and MDA were markedly higher in the hypothalamus of the HFD group. Summarizing, the results of our study indicate an adaptive brain response to the increased production of free radicals under insulin resistance conditions. Despite the increase in antioxidative defense systems, this mechanism does not protect both brain structures from oxidative damages. However, the cerebral cortex is more susceptible to oxidative stress caused by HFD.

Acrylamide (ACR) is a neurotoxic and carcinogenic compound found in many foods and industrial products, raising significant public health concerns. It induces oxidative stress, inflammation, and neurotransmitter disruption, all of which contribute to neuroinflammation. This study assessed the neuroprotective potential of germinated faba beans (Vicia faba L., cultivar Giza 843) against ACR-induced neurotoxicity in a rat model and compared two methods of germination (traditional germination (in light) and (germination in the dark)) to enhance their neuroprotective properties. The total phenolic, flavonoid, and antioxidant contents, as well as the profile of faba beans, were assessed via high-performance liquid chromatography (HPLC) and an amino acid analyser. Thirty-two Sprague‒Dawley rats ( n = 8/group) were randomly divided into the following groups: control, ACR-exposed, ACR coadministered with traditionally germinated fava bean extract (GFB), and ACR coadministered with ungerminated fava bean extract. Neuroinflammation was induced via the oral administration of ACR (35 mg/kg/day for 12 days), while GFB and ungerminated extracts were coadministered at 300 mg/kg/day for 12 days. Gait scores were assessed. Antioxidants (GSH, SOD), oxidative stress markers (MDA, NO), inflammatory cytokines (TNF-α, IL-6), neurotransmitters (GABA, serotonin, dopamine), and acetylcholinesterase activity were measured in brain tissues (cerebrum, cerebellum, hippocampus). Histopathology and immunohistochemistry (with anti-GFAP and anti-caspase-3 antibodies) were performed to assess structural damage and apoptotic cell death. The results revealed that, traditionally, germination yielded relatively high levels of bioactive compounds and increased antioxidant activity. Compared with the ACR and ungerminated groups, the optimised traditional germinated faba bean extract significantly reduced oxidative stress, inflammation, and neurotransmitter disruption. The increased neuroprotection was attributed to increased polyphenolic, flavonoid, and amino acid levels from traditional germination. The neuroprotective potential of faba beans against ACR toxicity can be enhanced through traditional germination methods. This finding presents a compelling, natural therapy for mitigating the serious public health concerns associated with ACR exposure, and further clinical trials are therefore needed. Graphical Abstract

Acrylamide (ACR) is extensively used in industrial areas and has been demonstrated to induce neurotoxicity via oxidative stress and apoptosis. In this study, we assessed the probable protective effects of thymoquinone (TQ), an active constituent of Nigella sativa, against ACR-induced neurotoxicity. ACR (50mg/kg, i.p., for 11 days) and TQ (2.5, 5 and 10mg/kg, i.p., for 11 days) were administered to rats. On 12th day, gait score was examined and rats were sacrificed. Malondialdehyde (MDA) and reduced glutathione (GSH) contents were determined in sciatic nerve. Furthermore, western blotting was conducted. The exposure of rats to ACR caused severe gait disabilities. The MDA and GSH contents were increased and decreased, respectively. ACR decreased P-ERK/ERK ratio and myelin basic protein (MBP) content, but significantly increased P-JNK/JNK, P-P38/P38, Bax/Bcl-2 ratios and caspase 3 and 9 levels. Concurrently administration of TQ (5 and 10mg/kg) with ACR, prevented gait abnormalities and meaningfully reduced MDA and elevated the GSH contents. Furthermore, TQ (5mg/kg) elevated the P-ERK/ERK ratio and MBP content while reduced the P-JNK/JNK, P-P38/P38 ratios and apoptotic markers. MAP kinase and apoptosis signaling pathways were involved in ACR-induced neurotoxicity in rat sciatic nerve and TQ significantly reduced ACR neurotoxicity. TQ afforded neuroprotection, in part, due to its anti-oxidative stress and anti-apoptotic mechanisms.

Preventive and therapeutic effects of azithromycin on acrylamide-induced neurotoxicity in rats

Objective:Acrylamide (ACR) neurotoxicity is induced by different mechanisms such as oxidative stress and apoptosis. Scientific researchs have indicated the antioxidative properties of Lippia citriodora. The protective effect of L. citriodora aqueous and ethanolic extracts on ACR-induced neurotoxicity was investigated.Materials and methods:Male Wistar rats were randomly divided into 13 groups: (1) control, (2) ACR (50 mg/kg, i.p.), (3-6) ACR+aqueous extract (12.5, 25, 50, and 100 mg/kg, i.p.), (7-10) ACR+ethanolic extract (12.5, 25, 50, and 100 mg/kg, i.p.), (11) aqueous extract (100 mg/kg), (12) ethanolic extract (100 mg/kg), and (13) ACR+Vitamin E (200 mg/kg, every other day, i.p.). After 11 days, gait score, MDA, and GSH levels in brain cortical tissue were measured. In the in vitro test, the viability of PC12 cells (using MTT test), the amount of reactive oxygen species (ROS; using DCFH-DA method), and the protein levels of Bax, Bcl2 and caspase 3 (by western blotting) were measured. Results:In the in vitro study, the IC50 for the treatment of PC 12 cells with ACR after 24 hr was 6 mM. ACR decreased cell viability, but increased ROS level, Bax/Bcl-2 ratio, and caspase-3 protein level. Pre-treatment by L. citriodora extracts (15-120 µg/ml) ameliorated the toxic effects of ACR on PC12 cells. In the in vivo experiment, ACR-induced movement disorders increased MDA but decreased GSH content. The extracts of L. citriodora improved ACR toxic effects. Conclusion:Aqueous and ethanolic extracts of L. citriodora were found to reduce ACR-induced neurotoxicity via inhibiting oxidative stress and apoptosis.

We have investigated the subtype of alpha2-adrenoceptor mediating prejunctional inhibition of neurotransmission in rat atrium in comparison with the alpha2-adrenoceptor mediating prejunctional inhibition in rat cerebral cortex. In rat atrium and cerebral cortex, prejunctional alpha2-adrenoceptors were investigated in terms of the ability of alpha2-adrenoceptor antagonists to increase the stimulation-evoked overflow of tritium in tissues pre-incubated with [3H]-noradrenaline. The relatively non-selective alpha2-adrenoceptor antagonist yohimbine and the alpha2D-adrenoceptor selective antagonist BRL 44408 had potencies in rat atrium which were similar to their potencies in rat cerebral cortex. The antagonists ARC 239, HV 723, WB 4101, prazosin, chlorpromazine and abanoquil, which have low affinity for alpha2D-adrenoceptors, significantly increased stimulation-evoked overflow at lower concentrations in rat atrium than rat cerebral cortex. Antagonist potency at prejunctional alpha2-adrenoceptors was correlated with antagonist affinity at alpha2-adrenoceptor ligand binding sites in membranes of rat kidney (alpha2B) and submandibular gland (alpha2D), and human recombinant alpha2C-adrenoceptors labelled with [3H]yohimbine. The correlation between ligand binding sites and the functional receptor in the rat cerebral cortex was significant only for the alpha2D-adrenoceptor ligand binding site (r=0.87, n=8, P<0.01) as compared to the alpha2B-adrenoceptor (r=0.32, n.s.) or alpha2C-adrenoceptor (r=0.12, n.s.) ligand binding sites. The correlation between ligand binding sites and the functional receptor in the rat atrium was not significant for any ligand binding site, with r=0.64, 0.68 and 0.67 for the alpha2D-, the alpha2B- and the alpha2C-adrenoceptor ligand binding sites, respectively. It is concluded that the functional prejunctional alpha2-adrenoceptor of rat cerebral cortex closely resembles the alpha2D-adrenoceptor ligand binding site of rat submandibular gland, but the rat atrium may contain two subypes of prejunctional alpha2-adrenoceptor, alpha2D and another subtype, possibly alpha2B or alpha2C.

The neurotoxicity of acrylamide (ACR) monomer occurs through different mechanisms such as oxidative stress. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) are green tea catechins which are known as powerful antioxidants. In this study, we examined the possible protective effects of ECG and EGCG on ACR neurotoxicity in both in-vitro and in-vivo models. PC12 cells were exposed to different concentrations of ECG and EGCG. After 24 and 48 hours, ACR was added to the cells (IC50 = 4.85 mM) and cell viability was measured through MTT assay after 24 hours. Male Wistar rats were pretreated with ECG, EGCG (10, 20 and 40 mg/kg, i.p) and vitamin E (200 IU/kg i.p.) for 3 days. Afterwards they were treated with ACR (50 mg/kg, i.p.) for 11 days. After the treatment period, gait score examination was performed and molondialdehyde (MDA) and reduced glutathione (GSH) were measured in cerebral cortex. ACR reduced the cell viability in a concentration-dependent manner. Both ECG and EGCG (20 μM) showed inhibitory effects on ACR cytotoxicity. ACR significantly induced gait abnormalities, decreased GSH level and increased lipid peroxidation in cerebral cortex. ECG and EGCG (20 mg/kg) improved all ACR toxic effects. Although the food intake was increased in pretreated groups compared to the ACR-treated group, intensive weight loss was observed due to the green tea’s different weight loss mechanisms. ECG and EGCG inhibited the cytotoxicity of ACR in PC12 cells and increased GSH level and decreased lipid peroxidation in rat cerebral cortex.

(1) In the present study we determined the effects of glutaric (GA, 0.01-1 mM) and 3-hydroxyglutaric (3-OHGA, 1.0-100 microM) acids, the major metabolites accumulating in glutaric acidemia type I (GA I), on Na(+)-independent and Na(+)-dependent [(3)H]glutamate binding to synaptic plasma membranes from cerebral cortex and striatum of rats aged 7, 15 and 60 days. (2) GA selectively inhibited Na(+)-independent [(3)H]glutamate binding (binding to receptors) in cerebral cortex and striatum of rats aged 7 and 15 days, but not aged 60 days. In contrast, GA did not alter Na(+)-dependent glutamate binding (binding to transporters) to synaptic membranes from brain structures of rats at all studied ages. Furthermore, experiments using the glutamatergic antagonist CNQX indicated that GA probably binds to non-NMDA receptors. In addition, GA markedly inhibited [(3)H]kainate binding to synaptic plasma membranes in cerebral cortex of 15-day-old rats, indicating that this effect was probably directed towards kainate receptors. On the other hand, experiments performed with 3-OHGA revealed that this organic acid did not change Na(+)-independent [(3)H]glutamate binding to synaptic membranes from cerebral cortex and striatum of rats from all ages, but inhibited Na(+)-dependent [(3)H]glutamate binding to membranes in striatum of 7-day-old rats, but not in striatum of 15- and 60-day-old rats and in cerebral cortex of rats from all studied ages. We also provided some evidence that 3-OHGA competes with the glutamate transporter inhibitor L-trans-pyrrolidine-2,4-dicarboxylate, suggesting a possible interaction of 3-OHGA with glutamate transporters on synaptic membranes. (3) These results indicate that glutamate binding to receptors and transporters can be inhibited by GA and 3-OHGA in cerebral cortex and striatum in a developmentally regulated manner. It is postulated that a disturbance of glutamatergic neurotransmission caused by the major metabolites accumulating in GA I at early development may possibly explain, at least in part, the window of vulnerability of striatum and cerebral cortex to injury in patients affected by this disorder.