An easy-to-use liquid chromatography method with fluorescence detection for the simultaneous determination of five neuroactive amino acids in different regions of rat brain

Postnatal propionic acid exposure disrupts hippocampal agmatine homeostasis leading to social deficits and cognitive impairment in autism spectrum disorder-like phenotype in rats

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by a range of symptoms including impaired social interaction and cognitive deficits. Although the exact pathogenesis of ASD is not well established, recent clinical findings suggest a decline in levels of biogenic amine agmatine in autistic patients. The present study was designed to investigate the impact of postnatal propionic acid (PPA) exposure on hippocampal agmatine homeostasis in male rat pups and to explore a new therapeutic intervention for ASD using agmatine as a biological target. PPA is commonly used in experimental models of ASD due to its ability to induce social deficits, cognitive impairments, and stereotyped behaviors, which closely resemble key characteristics of ASD. Male rat pups were administered with PPA via the intrahippocampal route bilaterally (25 μg/0.25 μl per side) on PND-21 to simulate the ASD phenotype, and its subsequent effect on the endogenous agmatinergic system. The influence of agmatine treatment and its endogenous modulation on ASD-like phenotypes was also investigated. Behavioral assessments revealed that PPA exposure reduced sociability and social preference, caused learning and memory impairment in the Morris water maze, increased anxiety-like behavior in the elevated plus maze, and reduced exploratory behavior in the hole board test. Neurochemical analyses showed a decrease in agmatine concentration and an increase in its degrading enzyme agmatinase in the hippocampus. PPA treatment altered the content of GABA, glutamate, TNF-α, IL-6, BDNF, and also resulted in increased astrogliosis and neurotoxicity within the hippocampus. Chronic agmatine treatment and its endogenous modulation ameliorated the behavioral and biochemical disruptions induced by PPA exposure. This study highlights the critical role of hippocampal agmatinergic pathway in the etiopathogenesis of ASD, positioning agmatine as a promising therapeutic target for its treatment.

Positive allosteric modulation of glutamate transporter reduces cocaine-induced locomotion and expression of cocaine conditioned place preference in rats

The glutamatergic system, located throughout the brain including the prefrontal cortex and nucleus accumbens, plays a critical role in reward and reinforcement processing, and mediates the psychotropic effects of addictive drugs such as cocaine. Glutamate transporters, including EAAT2/GLT-1, are responsible for removing glutamate from the synaptic cleft. Reduced expression of GLT-1 following chronic cocaine use and abstinence has been reported. Here, we demonstrate that targeting GLT-1 with a novel positive allosteric modulator (PAM), NA-014, results in reduction of cocaine-associated behaviors in rats. Pharmacokinetic analysis demonstrated that NA-014 is brain-penetrant and suitable for in vivo studies.We found that 15 and 30 mg/kg NA-014 significantly reduced cocaine-induced locomotion in males. Only the 15 mg/kg dose was effective in females and 60 mg/kg was ineffective in both sexes. Furthermore, 30 and 60 mg/kg NA-014 reduced expression of cocaine conditioned place preference (CPP) in males. 30 mg/kg NA-014 reduced expression of cocaine CPP in females and 15 mg/kg did not affect cocaine CPP in either sex, suggesting GLT-1 influences cocaine-associated behaviors in a sex-dependent manner. NA-014 did not elicit rewarding behavior, nor alter baseline locomotion. Twice daily/7-day administration of 100 mg/kg of NA-014 did not alter GLT-1 or GLAST expression in either sex in the prefrontal cortex (PFC). Collectively, these studies demonstrated that NA-014 reduced the locomotor stimulant and rewarding effects of cocaine in male and female rats. In the context of psychostimulant use disorders, our study suggests studying GLT-1 PAMs as alternatives to β-lactam compounds that increase GLT-1 protein levels.

Quantifying acute changes in neurometabolism following blast-induced traumatic brain injury

Brain health is largely dependent on the metabolic regulation of amino acids. Brain injuries, diseases, and disorders can be detected through alterations in free amino acid (FAA) concentrations; and thus, mapping the changes has high diagnostic potential. Common methods focus on optimizing neurotransmitter quantification; however, recent focus has expanded to investigate the roles of molecular precursors in brain metabolism. An isocratic method using high performance liquid chromatography with electrochemical cell detection was developed to quantify a wide range of molecular precursors and neurotransmitters: alanine, arginine, aspartate, serine, taurine, threonine, tyrosine, glycine, glutamate, glutamine, and γ-Aminobutyric acid (GABA) following traumatic brain injury. First, baseline concentrations were determined in the serum, cerebrospinal fluid, hippocampus, cortex, and cerebellum of naïve male Sprague Dawley rats. A subsequent study was performed investigating acute changes in FAA concentrations following blast-induced traumatic brain injury (bTBI). Molecular precursor associated FAAs decreased in concentration at 4 h after injury in both the cortex and hippocampus while those serving as neurotransmitters remained unchanged. In particular, the influence of oxidative stress on the observed changes within alanine and arginine pathways following bTBI should be further investigated to elucidate the full therapeutic potential of these molecular precursors at acute time points.

A high performance liquid chromatography tandem mass spectrometry protocol for detection of neurotransmitters in the rat brain tissue

The detection of neurotransmitters has extensively been applied to the study of the pathogenesis, diagnosis, and therapeutic effect of drugs on many neuropsychiatric diseases. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been employed to determine neurotransmitters levels due to its distinct advantages. However, neurotransmitter detection still presents some challenges. A rapid and sensitive HPLC-MS/MS protocol has been established in our lab, which can simultaneously detect 5 neurotransmitters with an easy pretreatment procedure. The protocol provides demanded reference value for the lab using an Agilent HPLC-MS/MS system with a triple quadrupole analyzer.

Artificial Intelligence in Functional Food Ingredient Discovery and Characterisation: A Focus on Bioactive Plant and Food Peptides

Scientific research consistently demonstrates that diseases may be delayed, treated, or even prevented and, thereby, health may be maintained with health-promoting functional food ingredients (FFIs). Consumers are increasingly demanding sound information about food, nutrition, nutrients, and their associated health benefits. Consequently, a nutrition industry is being formed around natural foods and FFIs, the economic growth of which is increasingly driven by consumer decisions. Information technology, in particular artificial intelligence (AI), is primed to vastly expand the pool of characterised and annotated FFIs available to consumers, by systematically discovering and characterising natural, efficacious, and safe bioactive ingredients (bioactives) that address specific health needs. However, FFI-producing companies are lagging in adopting AI technology for their ingredient development pipelines for several reasons, resulting in a lack of efficient means for large-scale and high-throughput molecular and functional ingredient characterisation. The arrival of the AI-led technological revolution allows for the comprehensive characterisation and understanding of the universe of FFI molecules, enabling the mining of the food and natural product space in an unprecedented manner. In turn, this expansion of bioactives dramatically increases the repertoire of FFIs available to the consumer, ultimately resulting in bioactives being specifically developed to target unmet health needs.

Simultaneous determination of five amino acid neurotransmitters in rat and porcine blood and brain by two-dimensional liquid chromatography

A method for the simultaneous determination of aspartic acid (Asp), glutamic acid (Glu), glycine (Gly), taurine (Tau) and gamma-aminobutyric acid (GABA) in animal blood and brain by two-dimensional liquid chromatography (2D-LC) combined with ultraviolet detection was established for the first time. First, the amino acid neurotransmitters (AANTs) were labeled on the corresponding fluorescent derivatives with 4-fluoro-7-nitrobenzofurazan (NBD-F), enriched on the extraction column and automatically transferred to the analytical column to achieve on-line extraction and complete separation of the target components. This method exhibited good selectivity, and the correlation coefficients for the analyte calibration curves of were > 0.99. The intra- and inter-day precisions were ≤ 16.03, and the accuracies were in the range of 70.59-116.20%. The system realizes the rapid detection and stability quantification of the five AANTs, which proves that the alternative dilution method is feasible. The results show that the system has high loading capacity, excellent resolution, and good peak shape and is not affected by other endogenous substances. Moreover, the developed method has been successfully applied to the analysis of biological samples in the blood and whole brain of rats and pigs. The content of AANTs in the hippocampus and cortex of rats was higher than that in those of pigs. This method is expected to provide applicability for the determination of AANTs in pharmacological, pharmaceutical and clinical research in nervous science.

Analytical methods for amino acid determination in organisms

Amino acids are important metabolites for tissue metabolism, growth, maintenance, and repair, which are basic life necessities. Therefore, summarizing analytical methods for amino acid determination in organisms is important. In the past decades, analytical methods for amino acids have developed rapidly but have not been fully explored. Thus, this article provides reference to analytical methods for amino acids in organisms for food and human research. Present amino acid analysis methods include thin-layer chromatography, high-performance liquid chromatography, liquid chromatography-mass spectrometer, gas chromatography-mass spectrometry, capillary electrophoresis, nuclear magnetic resonance, and amino acid analyzer analysis.

Effect of Shenfu injection on lipopolysaccharide (LPS)-induced septic shock in rabbits

ETHNOPHARMACOLOGICAL RELEVANCE

Shenfu injection is a popular Chinese herbal formula that has been widely used in the treatment of shock in China.

AIM OF THE STUDY

To investigate the effect of Shenfu injection on lipopolysaccharide (LPS)-induced septic shock in rabbits.

MATERIALS AND METHODS

We established a septic shock model in rabbits by administering an intravenous injection of 0.6 mg/kg LPS to anesthetized rabbit, and 15 min after LPS challenge, the rabbits were intravenously administered the Shenfu injection. In these in vivo experiments, the jugular vein of the rabbits was cannulated for LPS and drug administration, and the right common carotid artery was cannulated to record the mean arterial pressure (MAP) over a 6-h period. In addition, various serum biochemical parameters, including lactate dehydrogenase (LDH), aspartate aminotransferase (AST), glutamate transaminase (ALT), creatinine (Cre), and urea nitrogen (Urea), were measured at 0, 3, and 6 h. Serum LPS levels at 6 h were determined by the test kit. And histological changes in the heart, liver and kidney tissues were observed by HE staining. Furthermore, some related small molecules in the heart tissues were detected by MALDI-TOF-MSI.

RESULTS

We found that Shenfu injection can increase the MAP, decrease the serum LPS, LDH and AST levels, and improve the tissue morphology of the heart, liver and kidney in rabbits with LPS-induced septic shock. In addition, Shenfu injection can increase the contents of ATP and taurine while reducing the content of AMP in the heart tissue during septic shock.

CONCLUSIONS

These results indicate that Shenfu injection exerts a protective effect on LPS-induced septic shock in rabbits.

A Metabonomics Investigation into the Therapeutic Effects of BuChang NaoXinTong Capsules on Reversing the Amino Acid-Protein Interaction Network of Cerebral Ischemia

Background

Amino acids (AAs) in cerebrospinal fluid (CSF) play a pivotal role in cerebral ischemia (CI). BuChang NaoXinTong Capsules (BNC) are widely prescribed in Chinese medicine for the treatment of cerebrovascular and cardiovascular diseases.

Methods

In order to investigate the therapeutic effects and pharmacological mechanisms of BNC on reversing CI from a system level, an amino acid-protein interaction imbalanced network of CI containing metabolites of AAs, key regulatory enzymes, and proteins was constructed for the first time. Furthermore, a novel method for detecting the ten AAs in CSF was developed by UPLC-QQQ-MS in an effort to validate the imbalanced networks and the therapeutic effects of BNC via analysis of metabolites.

Results

Based on a middle cerebral artery occlusion (MCAO) rat model, the dynamic levels of amino acids in CSF 3, 6, 12, and 24 h after MCAO were analyzed. Up to 24 h, the accumulated nine AA biomarkers were found to significantly change in the MCAO group compared to the sham group and exhibited an obvious tendency for returning to baseline values after BNC treatment. In addition, based on the imbalanced network of CI, four key enzymes that regulate the generation of BNC-mediated AA biomarkers were selected and validated using an enzyme-linked immunosorbent assay and western blotting. Finally, aromatic-L-amino-acid decarboxylase (AADC) was found to be one of the putative targets for BNC-mediated protection against CI.

Conclusion

This study provides new strategies to explore the mechanism of cerebral ischemia and help discover the potential mechanism of BNC.