Nongenetic optical modulation of neural stem cell proliferation and neuronal/glial differentiation

Photostimulation has been widely used in neuromodulation. However, existing optogenetics techniques require genetic alternation of the targeted cell or tissue. Here, we report that neural stem cells (NSCs) constitutionally express blue/red light-sensitive photoreceptors. The proliferation and regulation of NSCs to neuronal or glial cells are wavelength-specific. Our results showed a 4.3-fold increase in proliferation and 2.7-fold increase in astrocyte differentiation for cells under low-power blue monochromatic light exposure (455 nm, 300 μW/cm²). The melanopsin (Opn4)/transient receptor potential channel 6 (TRPC6) non-visual opsin serves as a key photoreceptor response to blue light irradiation. Two-dimensional gel electrophoresis coupled with mass spectrometry further highlighted the Jun activation domain-binding protein 1 (Jab1) as a novel and specific modulator in phototransduction pathways induced by blue light exposure. Quiescent adult NSCs reside in specific regions of the mammalian brain. Therefore, we showed that melanopsin/TRPC6 expressed in these regions and blue light stimulation through optical fibers could directly stimulate the NSCs in vivo. Upconversion nanoparticles (UCNPs) converted deep-penetrating near-infrared (NIR) light into specific wavelengths of visible light. Accordingly, we demonstrated that UCNP-mediated NIR light could be used to modulate in vivo NSC differentiation in a less invasive manner. In the future, this light-triggered system of NSCs will enable nongenetic and noninvasive neuromodulation with therapeutic potential for central nervous system diseases.

Tendon stem/progenitor cell ageing: Modulation and rejuvenation

Tendon ageing is a complicated process caused by multifaceted pathways and ageing plays a critical role in the occurrence and severity of tendon injury. The role of tendon stem/progenitor cells (TSPCs) in tendon maintenance and regeneration has received increasing attention in recent years. The decreased capacity of TSPCs in seniors contributes to impaired tendon functions and raises questions as to what extent these cells either affect, or cause ageing, and whether these age-related cellular alterations are caused by intrinsic factors or the cellular environment. In this review, recent discoveries concerning the biological characteristics of TSPCs and age-related changes in TSPCs, including the effects of cellular epigenetic alterations and the mechanisms involved in the ageing process, are analyzed. During the ageing process, TSPCs ageing might occur as a natural part of the tendon ageing, but could also result from decreased levels of growth factor, hormone deficits and changes in other related factors. Here, we discuss methods that might induce the rejuvenation of TSPC functions that are impaired during ageing, including moderate exercise, cell extracellular matrix condition, growth factors and hormones; these methods aim to rejuvenate the features of youthfulness with the ultimate goal of improving human health during ageing.

Portal flow modulation in living donor liver transplantation: review with a focus on splenectomy

Small-for-size graft (SFSG) syndrome after living donor liver transplantation (LDLT) is the dysfunction of a small graft, characterized by coagulopathy, cholestasis, ascites, and encephalopathy. It is a serious complication of LDLT and usually triggered by excessive portal flow transmitted to the allograft in the postperfusion setting, resulting in sinusoidal congestion and hemorrhage. Portal overflow injures the liver directly through nutrient excess, endothelial activation, and sinusoidal shear stress, and indirectly through arterial vasoconstriction. These conditions may be attenuated with portal flow modulation. Attempts have been made to control excessive portal flow to the SFSG, including simultaneous splenectomy, splenic artery ligation, hemi-portocaval shunt, and pharmacological manipulation, with positive outcomes. Currently, a donor liver is considered a SFSG when the graft-to-recipient weight ratio is less than 0.8 or the ratio of the graft volume to the standard liver volume is less than 40%. A strategy for transplanting SFSG safely into recipients and avoiding extensive surgery in the living donor could effectively address the donor shortage. We review the literature and assess our current knowledge of and strategies for portal flow modulation in LDLT.

The Analytic Truth and Falsity of Disjunctions

Disjunctive inferences are difficult. According to the theory of mental models, it is because of the alternative possibilities to which disjunctions refer. Three experiments corroborated further predictions of the mental model theory. Participants judged that disjunctions, such as Either this year is a leap year or it is a common year are true. Given a disjunction such as Either A or B, they tended to evaluate the four cases in its 'partition': A and B, A and not-B, not-A and B, not-A and not-B, as 'possible' or 'impossible' in ways that bore out the difference between inclusive disjunctions ('or both') and exclusive disjunctions ('but not both'). Knowledge usually concerns what is true, and so when participants judge that a disjunction is false, or contingent, and evaluate the cases in its partition, they depend on inferences that yield predictable errors. They tended to judge that disjunctions, such as follows: Either the food is cold or else it is tepid, but not both, are true, though in fact they could be false. They tended to infer 'mirror-image' evaluations that yield the same possibilities for false disjunctions as those for true disjunctions. The article considers the implications of these results for alternative theories based on classical logic or on the probability calculus.

Effect of the essential oils from Piper sp. and blue led lights in the enhancement of the antibiotic activity of drugs against mdr bacterial strains

The indiscriminate use of antibiotics has made bacterial resistance an important public health problem, since many antibiotics have become ineffective. Phototherapy can be considered an alternative to reduce the abusive use of antimicrobials, thus impacting microbial resistance. The objective of this study was to determine the chemical profile and to evaluate the effect of blue LED lights on the antibacterial activity of essential oils from Piper species, as well as their aminoglycoside antibiotic activity modulation using the microdilution method to determine the Minimum Inhibitory Concentration (MIC). The antibiotic activity modulating effect of these oils was also determined using the broth microdilution method with 96-well plates which were exposed to LED light for 20 min. Chemical components were characterized by gas chromatography coupled to mass spectrometry, revealing β-copaen-4-α-ol, germacrene A and germacrene B as major essential oil constituents for Piper arboreum (OEPar), Piper aduncum (OEPad) and Piper gaudichaudianum (OEPg), respectively. OEPar obtained a MIC of 512 μg/mL against Staphylococcus aureus and a MIC ≥ 1024 μg/mL against Escherichia coli. OEPad and OEPg showed MIC values ≥ 1024 μg/mL against the utilized strains. The essential oils modulated the effect of the antibiotics amikacin and gentamicin, with this effect being potentiated when exposed to blue LED. The blue LED light in the absence of the essential oil also showed an ability to modulate aminoglycoside antibiotic activity in this study, presenting mostly synergistic effects. In conclusion, the results obtained in this study demonstrate that photodynamic therapy using blue LED light interferes with the antibacterial action of P. arboreum, P. aduncum and P. gaudichaudianum essential oils and aminoglycoside antibiotic activity.

Shearing overbite and asymmetrical jaw motions facilitate food breakdown in a freshwater stingray, Potamotrygon motoro

Many species of fish process their prey with cyclic jaw motions that grossly resemble those seen in mammalian mastication, despite starkly different tooth and jaw morphologies. The degree of similarity between the processing behaviors of these disparate taxa has implications for our understanding of convergence in vertebrate feeding systems. Here, we used XROMM (X-ray reconstruction of moving morphology) to investigate prey processing behavior of Potamotrygon motoro, the ocellate river stingray, which has recently been found to employ asymmetrical, shearing jaw motions to break down its prey. We found that P. motoro modulates its feeding kinematics to produce two distinct types of chew cycles: compressive cycles and overbite cycles. The latter are characterized by over-rotation of the upper jaw relative to the lower jaw, past the expected occlusal limit, and higher levels of bilateral asymmetry as compared with compressive chews. We did not find evidence of the mediolateral shearing motions typical of mammalian mastication, but overbite cycles appear to shear the prey item between the upper and lower toothplates in a propalinal fashion. Additionally, comparison of hyomandibular and jaw motions demonstrates that the angular cartilages decouple jaw displacement from hyomandibular displacement in rostrocaudal and mediolateral directions. The multiple similarities between mammalian mastication and the dynamic processing behavior of P. motoro support the use of sub-family Potamotrygoninae as a model for studying evolutionary convergence of mastication-like processing.

Lineage/species-specific expansion of the Mx gene family in teleosts: Differential expression and modulation of nine Mx genes in rainbow trout Oncorhynchus mykiss

Myxovirus resistance (Mx) proteins are interferon (IFN)-inducible Dynamin-like GTPases, which play an important role in antiviral immunity. Three Mx genes (Mx1-3) have been cloned previously in rainbow trout. In this study, an additional six Mx genes were cloned that reside in four chromosomal loci. Further bioinformatics analysis suggests the presence of three teleost Mx groups (TMG) each with a characteristic gene organisation. Salmonid Mx belong to TMG1 and TMG2. The increased salmonid Mx gene copies are due mainly to local gene duplications that happened before and after salmonid speciation, in a lineage/species specific manner. Trout Mx molecules have been diversified in the loop 1 and 4 regions, and in the nuclear localisation signal in loop 4. The trout Mx genes were shown to be differentially expressed in tissues, with high levels of expression of TMG1 (Mx1-4) in blood and TMG2 (Mx5-9) in intestine. The expression of the majority of the trout Mx genes was induced by poly IC in vitro and in vivo, and increased during development. In addition, induction by antiviral (IFN) and proinflammatory cytokines was studied, and showed that type I IFN, IFNγ and IL-1β can induce Mx gene expression in an Mx gene-, cytokine- and cell line-dependent manner. These results show that salmonids possess a large number Mx genes as well as complex regulatory pathways, which may contribute to their success in an anadromous life style.

Modulation of lipid metabolism and colonic microbial diversity of high-fat-diet C57BL/6 mice by inulin with different chain lengths

The physicochemical properties, biological functions and microbial degradation of inulins differ according to their degree of polymerization. However, the relationship between inulin activities and its effect on gut microbiota remains unknown. In this study, high fat diet with inulin (1 or 5 g/kg·bw), either with short or long chains groups were administered to different groups of mice (n = 10) for 10 weeks in order to investigate the effect of inulin on the microbial diversity of the animals. Litchi pericarp procyanidins (LPPC) were used for comparison purposes. Furthermore, the lipid metabolism and key regulator genes in mice were determined. The results indicated that natural inulin (1 g/kg·bw) ingestion reduced the body weight of fat mice between week 6-9. Glutathione peroxidase (GSH-Px) activity in liver was remarkably higher after adding long chain inulin (5 g/kg·bw) compared to high-fat-diet mice. Moreover, high dose of natural inulin regulated malondialdehyde and advanced glycation end-products levels in mice liver. Likewise, the high dose of short-chain inulin increased sterol response element binding protein 1 (SREBP-1), β-Hydroxy β-methylglutaryl-CoA (HMG-CoA) and ATP-binding cassette transporter A1 (ABCA1) genetic expression. A significant change on the abundance of six genera in gut microbial profile suggested that inulin has the ability to modulate the lipid metabolism regardless of chain length, mainly due to its impact on colon microbiota variety.

Second-order visual sensitivity in the aging population

Most visual and cognitive functions are affected by aging over the lifespan. In this study, our aim was to investigate the loss in sensitivity to different classes of second-order stimuli-a class of stimuli supposed to be mainly processed in extrastriate cortex-in the aging population. These stimuli will then allow one to identify specific cortical deficit independently of visibility losses in upstream parts of the visual pathway. For this purpose, we measured the sensitivity to first-order stimuli and second-order stimuli: orientation-modulated, motion-modulated or contrast-modulated as a function of spatial frequency in 50 aged participants. Overall, we observed a sensitivity loss for all classes of stimuli, but this loss differentially affects the three classes of second-order stimuli tested. It involves all modulation spatial frequencies in the case of motion modulation, but just high modulation spatial frequencies in the case of contrast- and orientation modulations. These observations imply that aging selectively affects the sensitivity to second-order stimuli depending on their type. Since there is evidence that these different second-order stimuli are processed in different regions of extrastriate cortex, this result may suggest that some visual cortical areas are more susceptible to aging effects than others.

Nanobodies: New avenues for imaging, stabilizing and modulating GPCRs

The family of G protein-coupled receptors (GPCRs) is the largest class of membrane proteins and an important drug target due to their role in many (patho)physiological processes. Besides small molecules, GPCRs can be targeted by biologicals including antibodies and antibody fragments. This review describes the use of antibodies and in particular antibody fragments from camelid-derived heavy chain-only antibodies (nanobodies/VHHs/sdAbs) for detecting, stabilizing, modulating and therapeutically targeting GPCRs. Altogether, it becomes increasingly clear that the small size, structure and protruding antigen-binding loops of nanobodies are favorable features for the development of selective and potent GPCRs-binding molecules. This makes them attractive tools to modulate GPCR activity but also as targeting modalities for GPCR-directed therapeutics. In addition, these antibody-fragments are important tools in the stabilization of particular conformations of these receptors. Lastly, nanobodies, in contrast to conventional antibodies, can also easily be expressed intracellularly which render nanobodies important tools for studying GPCR function. Hence, GPCR-targeting nanobodies are ideal modalities to image, stabilize and modulate GPCR function.

D2-like receptor agonist synergizes the μ-opioid agonist spinal antinociception in nociceptive, inflammatory and neuropathic models of pain in the rat

Opioids are potent analgesic drugs, but their use has been limited due to their side effects. Antinociceptive effects of D2-like receptor agonists such as quinpirole have been shown at the spinal cord level; however, their efficacy is not as high as that of opioids. Dopaminergic agonists are long-prescribed and well-tolerated drugs that have been useful to treat clinically and experimentally painful conditions. Because current pain treatments are not completely effective, the aim of this work was to determine if a D2-like receptor agonist improves the antinociceptive effects of a μ-opioid receptor agonist. Drugs were intrathecally administered in adult rats; mechanonociceptive and thermonociceptive tests were carried out. Intraplantar injection of complete Freund's adjuvant (CFA) and sciatic loose ligation (SLL) were used for inflammatory and neuropathic models of pain, respectively. In intact animals, D-Ala2, N-MePhe4, Gly-ol-enkephalin (DAMGO; a µ-opioid receptor agonist) increased the paw withdrawal latencies (PWL) in thermal and mechanical nociceptive tests in a dose-dependent manner. Quinpirole (D2-like receptor agonist) increased PWL only in mechanonociception. In the presence of quinpirole (1 nmol), the ED₅₀ of the mechanical antinociceptive effect of DAMGO was significantly decreased (8-fold). Coadministration of 1 nmol quinpirole and 30 pmol DAMGO completely reversed hyperalgesia in the CFA model, whereas 100 pmol DAMGO plus 1 nmol quinpirole reversed the allodynia in the SLL model. This work offers evidence about a synergistic antinociceptive effect between opioidergic and dopaminergic drugs. This combination may relieve painful conditions resistant to conventional treatments, and it may reduce the adverse effects of chronic opioid administration.

Comparative effect of black, green, oolong, and white tea intake on weight gain and bile acid metabolism

OBJECTIVE

The beneficial effects of tea on health, including obesity, are well known. However, the comparative effects of black, green, white, and oolong teas, which are prepared from the same fresh leaves, on weight gain and the potential mechanisms involved are not yet fully understood. Bile acids (BAs) are shown to be powerful regulators of metabolism; however, to our knowledge, no studies have investigated the effect of tea on BA metabolism. The aim of this study was to investigate the modulatory effects that green, black, white, and oolong teas that were prepared from the same raw tea leaves have on the plasma BA profile.

METHODS

Female rats were dosed with the aforementioned tea types as their sole source of drinking fluid for 28 d. We then investigated their weight and effect on BA metabolic profile using advanced ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS)-based metabolomics.

RESULTS

The UPLC-MS/MS analysis of the plasma show that the levels of murocholic acid, glycochenodeoxycholic acid, glycocholic acid, glycodeoxycholic acid, taurochenodeoxycholic acid, tauroursodeoxycholic acid, taurodeoxycholic acid, tauromuricholic acid, and taurocholic acid were increased; whereas levels of taurolithocholic acid and isolithocholic acid were decreased after drinking green, oolong, and white tea types compared with control. Surprisingly, oolong tea significantly influenced reduction in relative weight compared with control, black, and green tea; whereas black, green, and white teas had no effects on weight compared with control.

CONCLUSIONS

Green, black, oolong, and white teas altered the BA metabolism. This change in BA metabolism could be associated with the health benefit effects of tea. Oolong tea was most effective in reducing weight.

Coevolution pays off: Herpesviruses have the license to escape the DNA sensing pathway

Early detection of viral invasion by pattern recognition receptors (PRR) is crucial for the induction of a rapid and efficient immune response. Cytosolic DNA sensors are the most recently described class of PRR, and induce transcription of type I interferons (IFN) and proinflammatory cytokines via the key adaptor protein stimulator of interferon genes (STING). Herpesviruses are a family of large DNA viruses widely known for their immense arsenal of proteins dedicated to manipulating and evading host immune responses. Tantamount to the significant role played by DNA sensors and STING in innate immune responses, herpesviruses have in turn evolved a range of mechanisms targeting virtually every step of this key signaling pathway. Strikingly, some herpesviruses also take advantage of this pathway to promote their own replication. In this review, we will summarize the current understanding of DNA sensing and subsequent induction of signaling and transcription, and showcase the close adaptation of herpesviruses to their host reflected by the myriad of viral proteins dedicated to modulating this critical innate immune pathway.

Review: modulation of the oral microbiome by the host to promote ecological balance

The indivisible relationship between the human host and its oral microbiome has been shaped throughout the millennia, by facing various changes that have forced the adaptation of oral microorganisms to new environmental conditions. In this constant crosstalk between the human host and its microbiome, a bidirectional relationship has been established. The microorganisms provide the host with functions it cannot perform on its own and at the same time the host provides its microbes with a suitable environment for their growth and development. These host factors can positively affect the microbiome, promoting diversity and balance between different species, resulting in a state of symbiosis and absence of pathology. In contrast, other host factors can negatively influence the composition of the oral microbiome and drive the interaction towards a dysbiotic state, where the balance tilts towards a harmful relationship between the host and its microbiome. The aim of this review is to describe the role host factors play in cultivating and maintaining a healthy oral ecology and discuss mechanisms that can prevent its drift towards dysbiosis.

Bovine colostrum-driven modulation of intestinal epithelial cells for increased commensal colonisation

Nutritional intake may influence the intestinal epithelial glycome and in turn the available attachment sites for bacteria. In this study, we tested the hypothesis that bovine colostrum may influence the intestinal cell surface and in turn the attachment of commensal organisms. Human HT-29 intestinal cells were exposed to a bovine colostrum fraction (BCF) rich in free oligosaccharides. The adherence of several commensal bacteria, comprising mainly bifidobacteria, to the intestinal cells was significantly enhanced (up to 52-fold) for all strains tested which spanned species that are found across the human lifespan. Importantly, the changes to the HT-29 cell surface did not support enhanced adhesion of the enteric pathogens tested. The gene expression profile of the HT-29 cells following treatment with the BCF was evaluated by microarray analysis. Many so called "glyco-genes" (glycosyltransferases and genes involved in the complex biosynthetic pathways of glycans) were found to be differentially regulated suggesting modulation of the enzymatic addition of sugars to glycoconjugate proteins. The microarray data was further validated by means of real-time PCR. The current findings provide an insight into how commensal microorganisms colonise the human gut and highlight the potential of colostrum and milk components as functional ingredients that can potentially increase commensal numbers in individuals with lower counts of health-promoting bacteria.

Lateral line sensitivity in free-swimming toadfish Opsanus tau

A longstanding question in aquatic animal sensory physiology is the impact of self-generated movement on lateral line sensitivity. One hypothesis is that efferent modulation of the sensory hair cells cancels self-generated noise and allows fish to sample their surroundings while swimming. In this study, microwire electrodes were chronically implanted into the anterior lateral line nerve of oyster toadfish and neural activity was monitored during forward movement. Fish were allowed to freely swim or were moved by a tethered sled. In all cases, neural activity increased during movement with no evidence of efferent modulation. The anterior lateral line of moving fish responded to a vibrating sphere or the tail oscillations of a robotic fish, indicating that the lateral line also remains sensitive to outside stimulus during self-generated movement. The results suggest that during normal swim speeds, lateral line neuromasts are not saturated and retain the ability to detect external stimuli without efferent modulation.

Peptide Self-Assembly and Its Modulation: Imaging on the Nanoscale

This chapter intends to review the progress in obtaining site-specific structural information for peptide assemblies using scanning tunneling microscopy. The effects on assembly propensity due to mutations and modifications in peptide sequences, small organic molecules and conformational transitions of peptides are identified. The obtained structural insights into the sequence-dependent assembly propensity could inspire rational design of peptide architectures at the molecular level.

Effect of temperature change on synaptic transmission at crayfish neuromuscular junctions

Ectothermic animals in areas characterised by seasonal changes are susceptible to extreme fluctuations in temperature. To survive through varied temperatures, ectotherms have developed unique strategies. This study focuses on synaptic transmission function at cold temperatures, as it is a vital component of ectothermic animals' survival. For determining how synaptic transmission is influenced by an acute change in temperature (20°C to 10°C within a minute) and chronic cold (10°C), the crayfish (Procambarus clarkii) neuromuscular junction (NMJ) was used as a model. To simulate chronic cold conditions, crayfish were acclimated to 15°C for 1 week and then to 10°C for 1 week. They were then used to examine the synaptic properties associated with the low output nerve terminals on the opener muscle in the walking legs and high output innervation on the abdominal deep extensor muscle. The excitatory postsynaptic potentials (EPSPs) of the opener NMJs increased in amplitude with acute warming (20°C) after being acclimated to cold; however, the deep extensor muscles showed varied changes in EPSP amplitude. Synaptic transmission at both NMJs was enhanced with exposure to the modulators serotonin or octopamine. The membrane resistance of the muscles decreased 33% and the resting membrane potential hyperpolarised upon warm exposure. Analysis of haemolymph indicated that octopamine increases during cold exposure. These results suggest bioamine modulation as a possible mechanism for ensuring that synaptic transmission remains functional at low temperatures.

Isolation and characterization of the Bacillus cereus BC7 strain, which is capable of zearalenone removal and intestinal flora modulation in mice

Zearalenone (ZEN) causes serious diseases in both animals and humans and thereby leads to substantial economic losses. The elimination of ZEN contamination from food and feed is an important concern worldwide. This study aimed to screen a bacterium that can efficiently detoxify ZEN both in vitro and in vivo. A bacterium (designated BC7) with high ZEN-removing capability was isolated from mouldy contaminated feeds and characterized as Bacillus cereus based on biochemical and 16S rRNA sequencing analyses. BC7 could remove 100% and 89.31% of 10 mg/L ZEN in Luria-Bertani (LB) medium and simulated gastric fluid (GSF), respectively, within 24 h at 37 °C. The effects of BC7 on ZEN detoxification and on the intestinal flora were further evaluated using four groups of mice that were intragastrically administered normal saline, BC7 culture (CFU = 3.45 × 10⁸/mL), ZEN (10 mg/kg BW) or BC7 culture (CFU = 3.45 × 10⁸/mL) + ZEN (10 mg/kg BW) for 2 weeks. ZEN showed distinct reproductive and hepatic toxicity, as characterized by increased weights of the uterus and liver, altered levels of oestradiol (E2) and luteinizing hormone (LH), increased secretion of the liver injury biomarkers alanine transaminase (ALT) and aspartate transaminase (AST), and abnormal histological phenotypes for the uterus, ovary and liver. However, BC7 could significantly reduce all the above-mentioned adverse effects caused by ZEN with no harmful effect on the reproductive system and liver in mice. Moreover, the addition of BC7 could efficiently renormalize the ZEN-induced perturbation of the gut microbiota and significantly increase the abundance of Lactobacillus to maintain the health of the intestinal flora in mice. In conclusion, Bacillus cereus BC7 could be used as a potential feed additive to efficiently remove ZEN in vitro or in vivo and to normalize the disordered gut microbiota in mice.

Placebo Effect: Theory, Mechanisms and Teleological Roots

Why pain can be relieved with placebos is heavily debated. The term "placebo effect," implies that the placebo treatment induces pain relief which is imprecise because it is the mental cueing to the context of treatment and not the placebo itself that can reduce pain. This essay reverts to fundamentals of perception that have been used to explain how context generates predictions that can in turn effect the process of processing, organizing and interpreting of sensory inputs received from the periphery. We reinterpret placebo effect as a neurobiological phenomenon that occurs through the process of reward and aversive learning. The brain uses learnt information to generate predictions. The perceptual processes adjust the experience of pain to fit with the predictions generated from prior information. Placebo effect is thus understandably a result of the expectations and mental states that result from engaging in the process of treatment. These processes have teleological roots in ancient medicine and are the context that produces these responses is transforming with the evolution of modern medicine. Thus, when placebo effect is observed, the potent agent that induces pain reduction is not the placebo itself, but the mental cueing to the context of taking treatment.

CNS distribution, signalling properties and central effects of G-protein coupled receptor 4

Information on the distribution and biology of the G-protein coupled receptor 4 (GPR4) in the brain is limited. It is currently thought that GPR4 couples to Gs proteins and may mediate central respiratory sensitivity to CO2. Using a knock-in mouse model, abundant GPR4 expression was detected in the cerebrovascular endothelium and neurones of dorsal raphe, retro-trapezoidal nucleus locus coeruleus and lateral septum. A similar distribution was confirmed using RNAscope in situ hybridisation. In HEK293 cells, overexpressing GPR4, it was highly constitutively active at neutral pH with little further increase in cAMP towards acidic pH. The GPR4 antagonist NE 52-QQ57 effectively blocked GPR4-mediated cAMP accumulation (IC50 26.8 nM in HEK293 cells). In HUVEC which natively express GPR4, physiological acidification (pH 7.4-7.0) resulted in a cAMP increase by ∼55% which was completely prevented by 1 μM NE 52-QQ57. The main extracellular organic acid, l-lactic acid (LL; 1-10 mM), suppressed pH dependent activation of GPR4 in HEK293 and HUVEC cells, suggesting allosteric negative modulation. In unanaesthetised mice and rats, NE 52-QQ57 (20 mg kg-1) reduced ventilatory response to 5 and 10% CO2. In anaesthetised rats, systemic administration of NE 52-QQ57 (up to 20 mg kg-1) had no effect on hemodynamics, cerebral blood flow and blood oxygen level dependent responses. Central administration of NE 52-QQ57 (1 mM) in vagotomised anaesthetised rats did not affect CO2-induced respiratory responses. Our results indicate that GPR4 is expressed by multiple neuronal populations and endothelium and that its pH sensitivity is affected by level of expression and LL. NE 52-QQ57 blunts hypercapnic response to CO2 but this effect is absent under anaesthesia, possibly due to the inhibitory effect of LL on GPR4.

Differential effect of Androctonus australis hector venom components on macrophage KV channels: electrophysiological characterization

Neurotoxins of scorpion venoms modulate ion channels. Voltage-gated potassium (K_V) channels regulate the membrane potential and are involved in the activation and proliferation of immune cells. Macrophages are key components of the inflammatory response induced by scorpion venom. The present study was undertaken to investigate the effect of Androctonus australis hector (Aah) venom on K_V channels in murine resident peritoneal macrophages. The cytotoxicity of the venom was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) -based assay and electrophysiological recordings were performed using the whole-cell patch clamp technique. High doses of Aah venom (50, 125, 250 and 500 µg/ml) significantly decreased cell viability, while concentrations of 0.1-25 µg/ml were not cytotoxic towards peritoneal macrophages. Electrophysiological data revealed a differential block of K_V current between resting and LPS-activated macrophages. Aah venom significantly reduced K_V current amplitude by 62.5 ± 4.78% (n = 8, p < 0.05), reduced the use-dependent decay of the current, decreased the degree of inactivation and decelerated the inactivation process of K_V current in LPS-activated macrophages. Unlike cloned K_V1.5 channels, Aah venom exerted a similar blocking effect on K_V1.3 compared to K_V current in LPS-activated macrophages, along with a hyperpolarizing shift in the voltage dependence of K_V1.3 inactivation, indicating a direct mechanism of current inhibition by targeting K_V1.3 subunits. The obtained results, demonstrating that Aah venom differentially targets K_V channels in macrophages, suggest differential outcomes for their inhibitions, and that further investigations of scorpion venom immunomodulatory potential are required.

Role of prebiotics in regulation of microbiota and prevention of obesity

There is an increasing incidence in non-communicable diseases (NCD) such as obesity, diabetes and metabolic syndrome all over the world, despite of the governmental investments in healthy policies. Some of these diseases represent a high economic burden to individuals and society, demanding urgency in the identification of risk factors and appropriate solutions. Inadequate nutrition habits are an important risk factor for developing these diseases, and the consumption of functional foods such as prebiotics, probiotics, and phenolic compounds may contribute to mitigate them. It has been reported that the consumption of prebiotics can cause positive changes in the intestinal microbiota. The healthy microbiota, consisting mainly of Bifidobacterium and Lactobacillus, ferment prebiotics producing compounds that appear to play a protective role against metabolic diseases. Despite the growing number of publications on the effects of regular consumption of prebiotics in experimental models, additional studies on their effects on humans are needed to bring more subsidies to public health programs. This manuscript aims to review the literature on the possible benefits of ingestion of prebiotics in the control of obesity.

IGF-1 induces SOCS-2 but not SOCS-1 and SOCS-3 transcription in juvenile Nile tilapia (Oreochromis niloticus)

Insulin-like growth factor-1 (IGF-1) plays a crucial role in regulating growth in vertebrates whereas suppressors of cytokine signaling (SOCS) act as feedback inhibitors of the GH/IGF-1 axis. Although SOCS-2 binds the IGF-1 receptor and inhibits IGF-1-induced STAT3 activation, presently there is no clear evidence as to whether IGF-1 could induce SOCS gene expression. The current study aimed to determine whether IGF-1 could induce the transcription of SOCS in juvenile Nile tilapia (Oreochromis niloticus). We show that there is a common positive relationship between the mRNA expression of IGF-I and SOCS-2 under different nutritional statuses and stimulants, but not the mRNA expression of SOCS-1 and SOCS-3 Furthermore, rhIGF-1 treatment and transcriptional activity assay confirmed the hypothesis that IGF-1 could induce SOCS-2 expression, whereas it had no effect or even decreased the expression of SOCS-1 and SOCS-3 Overall, we obtained evidence that the transcription of SOCS-2, but not SOCS-1 or SOCS-3, could be induced by IGF signaling, suggesting that SOCS-2 serves as a feedback suppressor of the IGF-1 axis in juvenile Nile tilapia.

Modulation of ovine SBD-1 expression by Saccharomyces cerevisiae in ovine ruminal epithelial cells

Background

The ovine rumen is involved in host defense responses and acts as the immune interface with the environment. The ruminal mucosal epithelium plays an important role in innate immunity and secretes antimicrobial innate immune molecules that have bactericidal activity against a variety of pathogens. Defensins are cationic peptides that are produced by the mucosal epithelia and have broad-spectrum antimicrobial activity. Sheep β-defensin-1 (SBD-1) is one of the most important antibacterial peptides in the rumen. The expression of SBD-1 is regulated by the probiotic, Saccharomyces cerevisiae (S.c); however, the regulatory mechanism has not yet been elucidated. In the current study, the effects of S.c on the expression and secretion of SBD-1 in ovine ruminal epithelial cells were investigated using quantitative real-time PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA). In addition, specific inhibitors were used to block the nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), p38, JNK, and ERK1/2 signalling pathways separately or simultaneously, to determine the regulatory mechanism(s) governing S.c-induced SBD-1 upregulation.

Results

Incubation with S.c induced release of SBD-1 by ovine ruminal epithelial cells, with SBD-1 expression peaking after 12 h of incubation. The highest SBD-1 expression levels were achieved after treatment with 5.2 × 10⁷ CFU∙mL^− 1 S.c. Treatment with S.c resulted in significantly increased NF-κB, p38, JNK, ERK1/2, TLR2, and MyD88 mRNA expression. Whereas inhibition of mitogen-activated protein kinases (MAPKs) and NF-κB gene expression led to a decrease in SBD-1 expression.

Conclusions

S.c was induced SBD-1 expression and the S.c-induced up-regulation of SBD-1 expression may be related to TLR2 and MyD88 in ovine ruminal epithelial cells. This is likely simultaneously regulated by the MAPKs and NF-κB pathways with the p38 axis of the MAPKs pathway acting as the primary regulator. Thus, the pathways regulating S.c-induced SBD-1 expression may be related to TLR2-MyD88-NF-κB/MAPKs, with the TLR2-MyD88-p38 component of the TLR2-MyD88-MAPKs signalling acting as the main pathway.