gamma-Aminobutyric acid and cardiovascular function

Cardiovascular therapeutics: A new potential for anxiety treatment?

Besides the well‐recognized risk factors, novel conditions increasing cardiovascular morbidity and mortality are emerging. Undesirable emotions and behavior such as anxiety and depression, appear to participate in worsening cardiovascular pathologies. On the other hand, deteriorating conditions of the heart and vasculature result in disturbed mental and emotional health. The pathophysiological background of this bidirectional interplay could reside in an inappropriate activation of vegetative neurohormonal and other humoral systems in both cardiovascular and psychological disturbances. This results in circulus vitiosus potentiating mental and circulatory disorders. Thus, it appears to be of utmost importance to examine the alteration of emotions, cognition, and behavior in cardiovascular patients. In terms of this consideration, recognizing the potential of principal cardiovascular drugs to interact with the mental state in patients with heart or vasculature disturbances is unavoidable, to optimize their therapeutic benefit. In general, beta‐blockers, central sympatholytics, ACE inhibitors, ARBs, aldosterone receptor blockers, sacubitril/valsartan, and fibrates are considered to exert anxiolytic effect in animal experiments and clinical settings. Statins and some beta‐blockers appear to have an equivocal impact on mood and anxiety and ivabradine expressed neutral psychological impact. It seems reasonable to suppose that the knowledge of a patient's mood, cognition, and behavior, along with applying careful consideration of the choice of the particular cardiovascular drug and respecting its potential psychological benefit or harm might improve the individualized approach to the treatment of cardiovascular disorders.

Characterization and comparative genomic analysis of gamma-aminobutyric acid (GABA)-producing lactic acid bacteria from Thai fermented foods

OBJECTIVES

This study aimed to screen, characterize, and annotate the genome along with the comparison of GABA synthesis genes presented in lactic acid bacteria (LAB).

RESULTS

Thirty-five LAB isolates from fermented foods were screened for GABA production using thin-layer chromatography (TLC). Fifteen isolates produced GABA ranging from 0.07 to 22.94 g/L. Based on their GTG₅ profiles, phenotypic, and genotypic characteristics, isolates LSI1-1, LSI1-5, LSI2-1, LSI2-2, LSI2-3, LSI2-5, and LSM3-1-4 were identified as Lactobacillus plantarum subsp. plantarum; isolate LSM1-4 was Lactobacillus argentoratensis; isolates CAB1-2, CAB1-5, CAB1-7, and LSI1-4 were Lactobacillus pentosus; and CAB1-1, LSM3-1-1 and LSM3-2-3 were Lactobacillus fermentum. Strains LSI2-1 and CAB1-7 from pickled vegetables were selected for genome analysis. The gadA gene (1410 bp, 470aa) was encountered in GABA production of both strains and no other glutamate decarboxylase (GAD) genes were found in the genomes when compared with other LAB strains. The presence of gadA is evidence for GABA production. Strains LSI2-1 and CAB1-7 produced 22.94 g/L and 11.59 g/L of GABA in GYP broth supplemented with 3% (w/v) MSG at 30 °C for 72 h, respectively.

CONCLUSIONS

Our report highlights the characterization of LAB and GABA production of L. plantarum LSI2-1 strain with its GABA synthesis gene. GABA production of strains LSI2-1 and CAB1-7 in GYP broth with 3% (w/v) MSG and comparative GAD genes.

Tissue-Specific Landscape of Metabolic Dysregulation during Ageing

The dysregulation of cellular metabolism is a hallmark of ageing. To understand the metabolic changes that occur as a consequence of the ageing process and to find biomarkers for age-related diseases, we conducted metabolomic analyses of the brain, heart, kidney, liver, lung and spleen in young (9-10 weeks) and old (96-104 weeks) wild-type mice [mixed genetic background of 129/J and C57BL/6] using NMR spectroscopy. We found differences in the metabolic fingerprints of all tissues and distinguished several metabolites to be altered in most tissues, suggesting that they may be universal biomarkers of ageing. In addition, we found distinct tissue-clustered sets of metabolites throughout the organism. The associated metabolic changes may reveal novel therapeutic targets for the treatment of ageing and age-related diseases. Moreover, the identified metabolite biomarkers could provide a sensitive molecular read-out to determine the age of biologic tissues and organs and to validate the effectiveness and potential off-target effects of senolytic drug candidates on both a systemic and tissue-specific level.

Identification of a New Giant Emrbryo Allele, and Integrated Transcriptomics and Metabolomics Analysis of Giant Embryo Development in Rice

Rice embryos are rich in high-quality protein, lipid, vitamins and minerals, representing the most important nutritional part of brown rice. However, the molecular mechanism of rice embryo development is poorly understood. In this study, two rice cultivars with contrasting embryo size (the giant embryo cultivar Dapeimi and the normal embryo cultivar 187R) were used to explore excellent genes controlling embryo size, and the developed near-isogenic lines (NILs) (NIL-D, which has the giant embryo phenotype, and its matching line, NIL-X) were used to explore transcript and metabolic properties in the earlier maturation stage of giant embryo development under natural conditions. The map-based cloning results demonstrated that Dapeimi is a novel allelic mutant of the rice GIANT EMBRYO (GE) gene, and the functional mutation site is a single cytosine deletion in the exon1. A total of 285 differentially accumulated metabolites (DAMs) and 677 differentially expressed genes (DEGs) were identified between NIL-D and NIL-X. The analysis of DAMs indicated that plants lacking GE mainly promoted energy metabolism, amino acid metabolism, and lipid metabolism pathways in the rice embryo. Pearson correlation coefficient showed that 300 pairs of gene-metabolites were highly correlated. Among them, OsZS_02G0528500 and OsZS_12G0013700 were considered to be key genes regulating L-Aspartic acid and L-Tryptophan content during rice giant embryo development, which are promising to be good candidate genes to improve rice nutrition. By analyzing rice embryo development through a combination of strategies, this research contributes to a greater understanding of the molecular mechanism of rice embryo development, and provides a theoretical foundation for breeding high-nutrition varieties.

Snake venom three-finger toxins and their potential in drug development targeting cardiovascular diseases

Cardiovascular diseases such as coronary and peripheral artery diseases, venous thrombosis, stroke, hypertension, and heart failure are enormous burden to health and economy globally. Snake venoms have been the sources of discovery of successful therapeutics targeting cardiovascular diseases. For example, the first-in-class angiotensin-converting enzyme inhibitor captopril was designed largely based on bradykinin-potentiating peptides from Bothrops jararaca venom. In the recent years, sensitive and high throughput approaches drive discovery and cataloging of new snake venom toxins. As one of the largest class of snake venom toxin, there are now>700 sequences of three-finger toxins (3FTxs) available, many of which are yet to be studied. While the function of 3FTxs are normally associated with neurotoxicity, increasingly more 3FTxs have been characterized to have pharmacological effects on cardiovascular systems. Here we focus on this family of snake venom toxins and their potential in developing therapeutics against cardiovascular diseases.

Production of γ-aminobutyric acid in Escherichia coli by engineering MSG pathway

The compound γ-aminobutyric acid (GABA) has many important physiological functions. The effect of glutamate decarboxylases and the glutamate/GABA antiporter on GABA production was investigated in Escherichia coli. Three genes, gadA, gadB, and gadC were cloned and ligated alone or in combination into the plasmid pET32a. The constructed plasmids were transformed into Escherichia coli BL21(DE3). Three strains, E. coli BL21(DE3)/pET32a-gadA, E. coli BL21(DE3)/pET32a-gadAB and E. coli BL21(DE3)/pET32a-gadABC were selected and identified. The respective titers of GABA from the three strains grown in shake flasks were 1.25, 2.31, and 3.98 g/L. The optimal titer of the substrate and the optimal pH for GABA production were 40 g/L and 4.2, respectively. The highest titer of GABA was 23.6 g/L at 36 h in batch fermentation and was 31.3 g/L at 57 h in fed-batch fermentation. This study lays a foundation for the development and use of GABA.

Study of the rapid detection of γ-aminobutyric acid in rice wine based on chemometrics using near infrared spectroscopy

Rice wine, in which γ-aminobutyric acid is present, is beneficial to human health and is one of the three most well-known fermented wines in the world, and is very popular in China. The rapid detection of γ-aminobutyric acid was studied in rice wine using near infrared spectroscopy with an optical fibre probe. Through the selection of detection conditions, including a waveband range of 12500-4000 cm(-1), a scanning duration of 16 scans and a resolution of 8 cm(-1), the near infrared spectrum of rice wine was acquired three times, for every wine sample, with an optical fibre probe. The resulting average value of the spectrum was obtained and the corresponding data were analysed via normalization. By adopting a multivariate calibration partial least squares method (PLS) and establishing a calibration model, the highest precision for γ-aminobutyric acid in rice wine was predicted when the factor coefficient was 17. The overall results demonstrating the content of γ-aminobutyric acid in rice wine was predicted to be between 157.6696-317.5813 mg/L, with a relative standard deviation of prediction between 0.01-5 %, as well as the fact that the single sample measuring time was less than 20 s, prove that near infrared spectroscopy is a rapid, accurate and effective method to adopt for detecting the content of γ-aminobutyric acid in rice wine.

Research into the functional components and antioxidant activities of North China rice wine (Ji Mo Lao Jiu)

Over the last decade, considerable experimental evidence has supported the view that grape wine and South China rice wine are rich in diverse nutrients and have powerful antioxidant activity. However, little research has been carried out for North China rice wine, of which Ji Mo Lao Jiu (JMLJ) is the outstanding representative. In this study, the functional components and antioxidant activity of JMLJ were investigated. Twenty-eight free amino acids were found in JMLJ, much more than that previously reported in other Chinese rice wines (16-21). Functional oligosaccharides (5290.222 mg/L), total phenols (722.431 ± 10.970 mg/L), and mineral elements (9) were rich in JMLJ. When compared with synthetic antioxidants, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), JMLJ showed effective 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging and reducing capacity. The results of this study lay the foundation for promoting the utilization of JMLJ and the development of North China rice wine in the food industry.

Submerged fermentation of Lactobacillus rhamnosus YS9 for γ-aminobutyric acid (GABA) production

γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in central nervous system, and its application in drugs and functional foods has attracted great attention. To enhance production of γ-aminobutyric acid, Lactobacillus rhamnosus YS9, a strain isolated from Chinese traditional fermented food pickled vegetable, was grown under submerged fermentation. Its cultivation conditions were investigated. When culture pH condition was adjusted to the optimal pH of glutamate decarboxylase activity, culture of Lb. rhamnosus YS9 in medium supplemented with 200 mM of monosodium glutamate and 200 μM of pyridoxal phosphate (PLP), produced 187 mM of GABA.

Alterations in a hypothalamic GABA system in the spontaneously hypertensive rat

The density (Bmax) of muscimol and clonazepam binding to hypothalamic membranes from spontaneously hypertensive rats (SHR) was reduced compared to age-matched Wistar Kyoto (WKY) animals in the period 80 - 120 days. There were no significant differences in dissociation constant (Kd) for either ligand at this time. At 30 - 36 days, prior to development of pronounced hypertension, there were no differences in Kd or Bmax for either ligand in SHR and WKY animals. There were also deficits in endogenous hypothalamic GABA concentrations in SHR at 75 and 120 days as compared to WKY. The hypothesis is advanced, that there may be a dysfunction of a hypothalamic GABA system in the SHR rat as hypertension develops.

Medicinal chemistry of ρ GABAC receptors

The inhibitory neurotransmitter, GABA, is a low-molecular-weight molecule that can achieve many low-energy conformations, which are recognized by GABA receptors and transporters. In this article, we assess the structure–activity relationship profiles of GABA analogs at the ionotropic ρ GABAC receptor. Such studies have significantly contributed to the design and development of potent and selective agonists and antagonists for this subclass of GABA receptors. With these tools in hand, the role of ρ GABAC receptors is slowly being realized. Of particular interest is the development of selective phosphinic acid analogs of GABA and their potential use in sleep disorders, inhibiting the development of myopia, and in improving learning and memory.

Protective role of γ-aminobutyric acid against chronic renal failure in rats

The protective effect of γ-aminobutyric acid (GABA) against chronic renal failure (CRF) was investigated using a remnant kidney model with 5/6 nephrectomized rats. Nephrectomy led to renal dysfunction, which was evaluated via several parameters including serum urea nitrogen, creatinine (Cr) and Cr clearance. However, the administration of GABA ameliorated renal dysfunction, and a longer administration period of GABA increased its protective effect. In addition, nephrectomized control rats showed an elevation in the fractional excretion of sodium (FENa) with an increase in urinary sodium, while GABA led to a significant decline in FENa. Moreover, nephrectomy resulted in a decrease of serum albumin and an increase of urinary protein with a change in the urinary protein pattern, whereas the rats administered GABA showed improvement in these changes associated with CRF caused by nephrectomy. This suggests that GABA would inhibit the disease progression and have a protective role against CRF. As one of the risk factors for CRF progression, hypertension was also regulated by GABA. The results also indicate that GABA may play a protective role against CRF through improvement of the serum lipid profile, with reductions in triglyceride and total cholesterol. Furthermore, nephrectomy led to renal oxidative stress with a decrease in the activity of antioxidative enzymes and elevation of lipid peroxidation. The administration of GABA attenuated oxidative stress induced by nephrectomy through an increase in superoxide dismutase and catalase, and decrease in lipid peroxidation. The histopathological lesions, including glomerular, tubular and interstitial lesions, under nephrectomy were also improved by GABA with the inhibition of fibronectin expression. This study demonstrated that GABA attenuated renal dysfunction via regulation of blood pressure and lipid profile, and it also ameliorated the oxidative stress induced by nephrectomy, suggesting the promising potential of GABA in protecting against renal failure progression.

Protective effect of γ-aminobutyric acid against glycerol-induced acute renal failure in rats

To investigate the effect of gamma-aminobutyric acid (GABA) on acute renal failure, we used a rat model of acute tubular necrosis induced by glycerol. After deprivation of water for 6h, the rats received an injection of 50% glycerol into the muscle of the rear limb at 10 ml/kg body weight. GABA was then administered orally to the rats (100 or 500 mg/kg body weight/day) once every 12h for 3 days. The rats with acute renal failure showed arrested body weight gain and an increase of kidney weight, whereas oral administration of GABA attenuated the physiological changes induced by acute renal failure. However, GABA administration had no significant effect on increased urine volume. Oral administration of GABA at a dose of 100 or 500 mg/kg body weight/day for 3 days significantly improved the markedly elevated levels of blood urea nitrogen and creatinine and the reduced creatinine clearance related to progression of renal failure. Moreover, the rats with acute renal failure exhibited high levels of fractional excretion of sodium (FE(Na)) due to alteration of tubule function following injection of glycerol. However, administration of GABA lowered the FE(Na) levels dose-dependently. Furthermore, urine osmolarity was markedly reduced in control rats with acute renal failure as compared with normal rats, whereas it was significantly increased by administration of GABA at a dose of 500 mg/kg body weight/day. These results indicate that GABA has potential as a therapeutic agent against the renal damage involved in acute renal failure.

Reduced GABA inhibition of sympathetic function in renal-wrapped hypertensive rats

Animals with bilateral cannulas in the paraventricular nucleus were made hypertensive by a one-kidney, figure eight renal wrap procedure or sham operated. Femoral artery and vein catheters were inserted for arterial pressure measurement and plasma catecholamine determination. After recovery and 4 days after hypertension surgery, bicuculline methiodide or muscimol was microinjected into the paraventricular nucleus. In some rats, nitroprusside was infused intravenously to reflexly stimulate the sympathetic nervous system. In control rats, bicuculline increased blood pressure, heart rate, and plasma norepinephrine and epinephrine concentrations. In contrast, in hypertensive rats blood pressure did not change while the heart rate response was maintained. Plasma norepinephrine and epinephrine responses were reduced 75 and 68%, respectively. Muscimol injections decreased arterial pressure in the hypertensive rats. Heart rate responses to nitroprusside were similar in the two groups of rats, while the plasma catecholamine responses were attenuated in the hypertensive animals. These data suggest that GABA function in the paraventricular nucleus is reduced in renal wrap hypertension.

Effect of clonidine on blood pressure and GABAergic mechanisms in spontaneously hypertensive rats

The action of clonidine on blood pressure and on the functional state of the gamma-aminobutyric acid-ergic (GABAergic) system was studied. A single injection of clonidine (1, 5, 10, 20 micrograms.kg-1) induced a dose-dependent decrease of blood pressure. Chronic administration of clonidine, 10 micrograms.kg-1, produced the maximum effect after the third injection. The effect was maintained for the duration of the study. Single or chronic clonidine injections, at the dose of 10 micrograms.kg-1 enhanced the GABA content in the brain and hypothalamus. This effect was less pronounced in the hippocampus. The drug administered according to the same regimen stimulated glutamic acid decarboxylase activity only in the hypothalamus. Clonidine caused a marked enhancement of specific [3H]GABA binding in the hypothalamus. These data suggest that the hypotensive action of clonidine is related to stimulation of the GABAergic system.

A novel type of GABA receptor in rat spinal cord?

The depolarization-evoked release of gamma-aminobutyric acid (GABA) and its possible modulation mediated by autoreceptors were studied in nerve endings isolated from rat spinal cord and prelabeled with the radioactive aminoacid. In the presence of the GABA uptake inhibitor SK&F 89976A [N-(4,4-diphenyl-3-butenyl)-nipecotic acid], used to minimize carrier-mediated homoexchange, exogenous GABA (1-10 mumol/l) decreased in a concentration-dependent way the release of 3H-GABA evoked by 15 mmol/l KCl. The GABAA receptor agonist muscimol (10-100 mumol/l) did not affect the K+ (15 mmol/l)-evoked 3H-GABA release. Similarly ineffective was the GABAB receptor agonist (-)-baclofen (3-100 mumol/l). The effect of GABA was not counteracted by the GABAA receptor antagonists bicuculline,picrotoxin or SR95531 [2-(3'-carbethoxy-2'-propenyl)-3-amino-6-paramethoxy-phenyl-pyr idazinium bromide].(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of baroreflex following microinjection of GABA or morphine into the nucleus tractus solitarii in rabbits

The possibility that putative transmitters may influence the aortic nerve stimulation-produced bradycardia and depressor responses was examined in urethane- and chloralose-anesthetized, paralyzed and artificially ventilated rabbits. The ipsilateral microinjection of gamma-aminobutyric acid (GABA, 2-4 micrograms) or morphine hydrochloride (2-4 micrograms) into the nucleus tractus solitarii (NTS) area could partially block the evoked bradycardia and depressor responses produced by stimulation of the aortic nerve without influencing the basal blood pressure and heart rate. This blocking effect of either GABA or morphine was dose-related. Pretreatment with GABA receptor antagonist bicuculline methiodide (0.15-0.20 micrograms) and opiate receptor antagonist naloxone hydrochloride (1-2 micrograms) into the same medullary area completely abolished the effect of GABA and morphine, respectively. Application of bicuculline also greatly antagonized the effect of morphine, but the blocking effect of GABA on the evoked bradycardia and depressor responses still existed following the pretreatment of naloxone. These results indicate that GABAergic and opiate systems present at the NTS exert an inhibitory influence on the evoked baroreflexes and inhibitory effect of the latter may be related to the activation of GABAergic receptor in this nucleus.

Central receptor binding and cardiovascular effects of GABA analogues in the cat

Several structural analogues of GABA were shown to be inhibitors of GABAA receptor binding in membranes from cat cerebral cortex. These compounds were 3-aminopropanesulfonic acid (APS; IC50 = 0.04 microM), imidazoleacetic acid (IMA; IC50 = 0.4 microM), morpholinopropanesulfonic acid (MOPS; IC50 = 1.6 microM), 5-phenylpyrrolepropionic acid (PPP; IC50 = 15 microM), aminoethanethiosulfonic acid (AETS; IC50 = 22 microM), 3-amino-3-phenylpropionic acid (APP; IC50 = 35 microM), meta-aminobenzoic acid (MABA; IC50 = 58 microM) and urocanic acid (UCA; IC50 = 354 microM). The IC50 value for GABA was 0.03 microM. GABA, PPP, AETS, MABA and UCA were previously shown to reduce arterial pressure in the cat after intracerebroventricular infusion. In the present study MOPS (ED50 = 0.26 nmol/kg), APS (ED50 = 4.7 nmol/kg), APP (ED50 = 49 nmol/kg), and IMA (ED50 = 350 nmol/kg) were also found to be able to decrease blood pressure when infused into the fourth ventricle. All nine compounds reduced blood pressure to the same extent, but in some cases their relative potencies (ED50 values) exhibited significant differences. When the IC50 values for receptor binding were plotted against the ED50 values for the cardiovascular effects, no significant correlation emerged. This lack of a correlation does not necessarily imply that the reductions in blood pressure elicited by the drugs are not related to an activation of central GABAA receptors. Instead, it highlights the difficulties that are sometimes encountered in attempting to obtain quantitative measurements after intracerebroventricular infusion.

Novel GABA analogues as hypotensive agents

The actions of four analogues of gamma-aminobutyric acid (GABA) on blood pressure and heart rate were measured in the cat after intracerebroventricular administration. These compounds were previously found to inhibit binding to GABAA receptors of neuronal membranes from the CNS of the rat. Each of the drugs, together with GABA, produced an average maximum reduction in blood pressure of 27.63% +/- 12.5. However, aminoethanethiosulfonic acid (AETS) was the most potent (ED50 = 2.24 X 10(-10) mol/kg) of the drugs, followed by 5-phenyl-2-pyrrole propionic acid (PPP), urocanic acid (UCA), m-aminobenzoic acid (MABA) and GABA. None of the compounds produced a significant effect on heart rate. The fact that these analogues mimicked the action of GABA on the cardiovascular system of the cat and that they were able to inhibit binding to GABAA receptors, indicates that they may be GABA agonists.

The GABA/benzodiazepine receptor complex in the nervous system of a hypertensive strain of rat

gamma-Aminobutyric acid (GABA) has been implicated in the development of hypertension and in the regulation of blood pressure. The spontaneously hypertensive rat (SHR) offers an opportunity to explore the role of central GABA and other neurotransmitters in the genesis of high blood pressure. The receptor binding of [3H]GABA, [3H]flunitrazepam, and [3H]glutamate to synaptic membranes from the cerebral cortex and cerebellum of SHR rats were measured in animals of various ages. No significant differences between the SHR and a normotensive control strain of rats were found for any of the assays. The results indicate that in this model of hypertension, neither GABA nor glutamate function are involved, at least not in the cerebral cortex or cerebellum.