Epinephrine-dependent control of glucose metabolism in white adipose tissue: the role of α- and β-adrenergic signalling

Bactericidal activity of esculetin is associated with impaired cell wall synthesis by targeting glutamate racemase of Neisseria gonorrhoeae

Neisseria gonorrhoeae (NG), the causative organism of gonorrhea, has been classified by the World Health Organization as 'Priority' two organism owing to its increased resistance to antibiotics and even failure of recommended dual therapy with ceftriaxone and azithromycin. As a result, the general and reproductive health of infected individuals is severely compromised. The imminent public health catastrophe of antimicrobial-resistant gonococci cannot be understated, as t he of severe complications and sequelae of infection are not only increasing but their treatment has also become more expensive. Tenacious attempts are underway to discover novel drug targets as well as new drugs to fight against NG. Therefore, a considerable number of phytochemicals have been tested for their remedial intercession via targeting bacterial proteins. The MurI gene encodes for an enzyme called glutamate racemase (MurI) that is primarily involved in peptidoglycan (PG) biosynthesis and is specific to the bacterial kingdom and hence can be exploited as a potential drug target for the treatment of bacterial diseases. Accordingly, diverse families of phytochemicals were screened in silico for their binding affinity with N. Gonorrhoeae MurI (NG-MurI) protein. Esculetin, one of the shortlisted compounds, was evaluated for its functional, structural, and anti-bacterial activity. Treatment with esculetin resulted in growth inhibition, cell wall damage, and altered permeability as revealed by fluorescence and electron microscopy. Furthermore, esculetin inhibited the racemization activity of recombinant, purified NG-MurI protein, one of the enzymes required for peptidoglycan biosynthesis. Our results suggest that esculetin could be further explored as a lead compound for developing new drug molecules against multidrug-resistant strains.

Effect of different doses of the catecholamine epinephrine on antioxidant responses of larvae of the flesh fly Sarcophaga dux

The production and use of pharmaceutical products have increased over the past decades, and several are considered potential or proved hazardous wastes. When contaminating the environment, they can severely impact biodiversity. The catecholamine epinephrine (adrenaline) is no exception. Epinephrine can be administered as growth promoter in cattle, and is used for anaphylaxis treatment in human. While a range of studies has examined the effects of this catecholamine on vertebrate tissues, and evidenced that it can disrupt the oxidative stress status, the effects epinephrine could have on insects have remained poorly considered. Here, we examined the physiological effects of different concentrations (0, 25, 50, and 100 μg/mL) of epinephrine on larvae of the flesh fly Sarcophaga dux. Following experimental treatments, levels of H₂O₂, GSH, CAT, GPx, and CEH were measured from the fat body, cuticle, gut, and hemolymph of 3rd instars. Significant differences are reported for these physiological endpoints among the considered body compartments, and epinephrine concentrations. Epinephrine treatments did not increase reactive oxygen species production (H₂O₂ amounts), except for gut tissues. Increased levels of GSH suggest that epinephrine may have enhanced glucose metabolism and flux towards the pentose phosphate pathway, while reducing glutamine oxidation. CAT activity was slightly increased when the concentration of epinephrine was higher. The decreased GPx activity in the fat body was consistent with GSH variations. In sum, the injection of epinephrine seemed to elicit the antioxidant response in S. dux larvae, in turn attenuating ROS production.

Comparison of the sympathetic stimulatory abilities of B-type procyanidins based on induction of uncoupling protein-1 in brown adipose tissue (BAT) and increased plasma catecholamine (CA) in mice

OBJECTIVES

We previously found that elevated energy expenditure following a single oral dose of flavan 3-ols (FL), a mixture of catechins and B type procyanidins, is caused by sympathetic nerve activation. In the present study, we compared the activity of the FL components (-)-epicatechin (EC; monomer), procyanidin B2 (B2; dimer), procyanidin C1 (C1; trimer), cinnamtannin A2 (A2; tetramer), and more than pentamer fraction (P5).

METHODS

Male ICR mice were treated with a single oral dose of FL, EC, B2, C1, A2, or P5. The animals were sacrificed and blood and brown adipose tissue (BAT) sampled. The plasma catecholamine (CA) levels and BAT uncoupling protein (UCP)-1 mRNA expression were determined.

RESULTS

A single dose of 10 mg/kg FL significantly increased plasma CA and UCP-1 mRNA levels. B2, C1, and A2, but not EC and P5 (all at 1 mg/kg), significantly increased plasma adrenaline levels. Plasma noradrenaline was significantly elevated by B2 and A2, but not by EC, C1, or P5. UCP-1 mRNA levels were significantly increased by C1 and P5. In the dose response study of A2, 10-3 mg/kg A2 increased UCP-1 mRNA levels significantly, but not 10-2 and 10-1 mg/kg A2. In addition, combination treatment with 10-1 mg/kg A2 and yohimbine, an α2 adrenalin blocker, remarkably increased UCP-1 mRNA levels.

CONCLUSION

These results suggest that FL and its components, except EC, increase UCP-1 mRNA and plasma CA with varying efficacy.

Neural regulation of cancer: from mechanobiology to inflammation

Despite recent progress in cancer research, the exact nature of malignant transformation and its progression is still not fully understood. Particularly metastasis, which accounts for most cancer death, is a very complex process, and new treatment strategies require a more comprehensive understanding of underlying regulatory mechanisms. Recently, the sympathetic nervous system (SNS) has been implicated in cancer progression and beta-blockers have been identified as a novel strategy to limit metastasis. This review discusses evidence that SNS signaling regulates metastasis by modulating the physical characteristics of tumor cells, tumor-associated immune cells and the extracellular matrix (ECM). Altered mechanotype is an emerging hallmark of cancer cells that is linked to invasive phenotype and treatment resistance. Mechanotype also influences crosstalk between tumor cells and their environment, and may thus have a critical role in cancer progression. First, we discuss how neural signaling regulates metastasis and how SNS signaling regulates both biochemical and mechanical properties of tumor cells, immune cells and the ECM. We then review our current knowledge of the mechanobiology of cancer with a focus on metastasis. Next, we discuss links between SNS activity and tumor-associated inflammation, the mechanical properties of immune cells, and how the physical properties of the ECM regulate cancer and metastasis. Finally, we discuss the potential for clinical translation of our knowledge of cancer mechanobiology to improve diagnosis and treatment.

Obesity-associated sympathetic overactivity in children and adolescents: the role of catecholamine resistance in lipid metabolism

BACKGROUND

Obesity in children and adolescents is characterized by chronic sympathetic overdrive and reduced epinephrine-stimulated lipolysis. This resistance to catecholamines occurs during the dynamic phase of fat accumulation. This review will focus on the relationship between sympathetic-adrenal activity and lipid metabolism, thereby highlighting the role of catecholamine resistance in the development of childhood obesity.

RESULTS AND CONCLUSIONS

Catecholamine resistance causes lipid accumulation in adipose tissue by reducing lipolysis, increasing lipogenesis and impeding free fatty acid (FFA) transportation. Exercise improves catecholamine resistance, as evidenced by attenuated systemic sympathetic activity, reduced circulating catecholamine levels and enhanced β-adrenergic receptor signaling. Insulin resistance is mostly a casual result rather than a cause of childhood obesity. Therefore, catecholamine resistance in childhood obesity may promote insulin signaling in adipose tissue, thereby increasing lipogenesis. This review outlines a series of evidence for the role of catecholamine resistance as an upstream mechanism leading to childhood obesity.

Adrenaline and noradrenaline: protectors against oxidative stress or molecular targets?

Density functional theory was used to investigate the potential role of neurotransmitters adrenaline and noradrenaline regarding oxidative stress. It is predicted that they can be efficient as free radical scavengers both in lipid and aqueous media, with the main reaction mechanism being the hydrogen transfer and the sequential proton loss electron transfer, respectively. Despite the polarity of the environment, adrenaline and noradrenaline react with (•)OOH faster than Trolox, which suggests that they are better peroxyl radical scavengers than the reference compound. Both catecholamines are also proposed to be capable of efficiently inhibiting the oxidative stress induced by copper(II)-ascorbate mixtures, and the (•)OH production via Haber-Weiss reaction, albeit the effects on the later are only partial. They exert such beneficial effects by sequestering Cu(II) ions. In summary, these catecholamines can be capable of reducing oxidative stress, by scavenging free radicals and by sequestering metal ions. However, at the same time they might lose their functions in the process due to the associated structural modifications. Consequently, adrenaline and noradrenaline can be considered as both protectors and molecular targets of oxidative stress. Fortunately, under the proper conditions, both catecholamines can be regenerated to their original form so their functions are restored.

Analysis of the "endocannabinoidome" in peripheral tissues of obese Zucker rats

The endocannabinoid system (ECS) represents one of the major determinants of metabolic disorders. We investigated potential changes in the endogenous levels of anandamide (AEA), 2-arachidonoylglycerol (2-AG), N-oleoylethanolamine (OEA) and N-palmitoylethanolamine (PEA) in some peripheral organs and tissues of obese Zucker(fa/fa) and lean Zucker(fa/+) rats by qPCR, liquid chromatography mass spectrometry, western blot and enzymatic activity assays. At 10-12 weeks of age AEA levels were significantly lower in BAT, small intestine and heart and higher in soleus of Zucker(fa/fa) rats. In this tissue, also the expression of CB1 receptors was higher. By contrast in Zucker(fa/fa) rats, 2-AG levels were changed (and lower) solely in the small and large intestine. Finally, in Zucker(fa/fa), PEA levels were unchanged, whereas OEA was slightly lower in BAT, and higher in the large intestine. Interestingly, these differences were accompanied by differential alterations of the genes regulating ECS tone. In conclusion, the levels of endocannabinoids are altered during obesity in a way partly correlating with changes of the genes related to their metabolism and activity.

Identification of metabolic pathways influenced by the G-protein coupled receptors GprB and GprD in Aspergillus nidulans

Heterotrimeric G-protein-mediated signaling pathways play a pivotal role in transmembrane signaling in eukaryotes. Our main aim was to identify signaling pathways regulated by A. nidulans GprB and GprD G-protein coupled receptors (GPCRs). When these two null mutant strains were compared to the wild-type strain, the ΔgprB mutant showed an increased protein kinase A (PKA) activity while growing in glucose 1% and during starvation. In contrast, the ΔgprD has a much lower PKA activity upon starvation. Transcriptomics and ¹H NMR-based metabolomics were performed on two single null mutants grown on glucose. We noted modulation in the expression of 11 secondary metabolism gene clusters when the ΔgprB and ΔgprD mutant strains were grown in 1% glucose. Several members of the sterigmatocystin-aflatoxin gene cluster presented down-regulation in both mutant strains. The genes of the NR-PKS monodictyphenone biosynthesis cluster had overall increased mRNA accumulation in ΔgprB, while in the ΔgprD mutant strain the genes had decreased mRNA accumulation. Principal component analysis of the metabolomic data demonstrated that there was a significant metabolite shift in the ΔgprD strain. The ¹H NMR analysis revealed significant expression of essential amino acids with elevated levels in the ΔgprD strain, compared to the wild-type and ΔgprB strains. With the results, we demonstrated the differential expression of a variety of genes related mainly to secondary metabolism, sexual development, stress signaling, and amino acid metabolism. We propose that the absence of GPCRs triggered stress responses at the genetic level. The data suggested an intimate relationship among different G-protein coupled receptors, fine-tune regulation of secondary and amino acid metabolisms, and fungal development.

Peripheral adrenoceptors: the impetus behind glucose dysregulation and insulin resistance

It is now accepted that several pharmacological drug treatments trigger clinical manifestations of glucose dysregulation, such as hyperglycaemia, glucose intolerance and insulin resistance, in part through poorly understood mechanisms. Persistent sympathoadrenal activation is linked to glucose dysregulation and insulin resistance, both of which significantly increase the risk of emergent endocrinological disorders, including metabolic syndrome and type 2 diabetes mellitus. Through the use of targeted mutagenesis and pharmacological methods, preclinical and clinical research has confirmed physiological glucoregulatory roles for several peripheral α- and β-adrenoceptor subtypes. Adrenoceptor isoforms in the pancreas (α(2A) and β(2) ), skeletal muscle (α(1A) and β(2) ), liver (α(1A & B) and β(2) ) and adipose tissue (α(1A) and β(1 & 3) ) are convincing aetiological targets that account for both immediate and long-lasting alterations in blood glucose homeostasis. Because significant overlap exists between the therapeutic applications of numerous classes of drugs and their associated adverse side-effects, a better understanding of peripheral adrenoceptor-mediated glucose metabolism is thus warranted. Therefore, at the same time as providing a brief review of glucose homeostasis in the periphery, the present review addresses both functional and pathophysiological roles of the mammalian α(1) , α(2) , and β-adrenoceptor isoforms in whole-body glucose turnover. We highlight evidence relating to the clinical use of common adrenergic drugs and their impacts on glucose metabolism.

Vascular and metabolic effects of adrenaline in adipose tissue in type 2 diabetes

Objective:

The aim was to investigate adipose tissue vascular and metabolic effects of an adrenaline infusion in vivo in subjects with and without type 2 diabetes mellitus (T2DM).

Design:

Clinical intervention study with 1-h intravenous adrenaline infusion.

Subjects:

Eight male overweight T2DM subjects and eight male weight-matched, non-T2DM subjects were studied before, during and after an 1-h intravenous adrenaline infusion. Adipose tissue blood flow (ATBF) was determined by ¹³³Xenon wash-out technique, and microvascular volume in the adipose tissue was studied by contrast-enhanced ultrasound imaging. Adipose tissue fluxes of glycerol, non-esterified fatty acids (NEFA), triacylglycerol and glucose were measured by Fick's principle after catherisation of a radial artery and a vein draining the abdominal, subcutaneous adipose tissue.

Results:

ATBF increased similarly in both groups during the adrenaline infusion. One hour post adrenaline, ATBF was still increased in overweight T2DM subjects. Adrenaline increased microvascular volume in non-T2DM subjects while this response was impaired in overweight T2DM subjects. Adrenaline-induced increase in lipolysis was similar in both groups, but NEFA output from adipose tissue was delayed in overweight T2DM subjects. Glucose uptake in adipose tissue increased in non-T2DM subjects during adrenaline infusion but was unchanged in overweight T2DM subjects. This results in a delayed excess release of NEFA from the adipose tissue in overweight T2DM subjects after cessation of the adrenaline infusion.

Conclusion:

Capillaries in the adipose tissue are recruited by adrenaline in non-T2DM subjects; however, this response is impaired in overweight T2DM subjects. NEFA, released in adipose tissue during adrenaline stimulation, is insufficiently re-esterified in situ in overweight T2DM subjects, probably owing to increased ATBF after adrenaline infusion and inability to increase adipose tissue glucose uptake.