The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform

Naim Akhtar Khan - One of the best experts on this subject based on the ideXlab platform.

  • Oleanolic acid improves diet-induced obesity by modulating fat preference and inflammation in mice
    Biochimie, 2018
    Co-Authors: Fatima Zohra Djeziri, Meriem Belarbi, Babar Murtaza, Aziz Hichami, Chahid Benammar, Naim Akhtar Khan
    Abstract:

    Abstract Obesity, triggered by high-fat diet (HFD), is associated to altered Gustatory Perception of dietary lipids. Oleanolic acid (OLA), a triterpene, has been reported to exert anti-obesity effects in animal models. Hence, we investigated the role of OLA in the modulation of oro-sensory Perception of lipids in control and HFD-induced obese mice. As expected, OLA-treated obese mice exhibited a decrease in body, liver, and visceral adipose tissue weights. OLA treatment improved glucose tolerance, insulin level, plasma lipopolysaccharide (LPS), and hepatic cholesterol and triglyceride concentrations. OLA-treated obese mice exhibited higher fat preference compared to untreated obese mice, probably due to the increase in mRNA encoding CD36, a fat taste receptor, in mouse taste bud cells (mTBC). This phenomenon was associated with fatty-acid induced increases in free intracellular calcium concentrations, [Ca2+]i, induced in mTBC from OLA-treated obese mice. OLA also influenced the expression of mRNA encoding pro-inflammatory cytokines (IL-1β and IL-6) and some lipogenic genes (PPARα, SREBP1, FAS, ChREBP, and G6Pase) in liver and adipose tissue. These findings reveal that OLA improves Gustatory Perception of lipids and exerts protective effects in obesity.

  • CD36 gene polymorphism is associated with Alzheimer's disease.
    Biochimie, 2017
    Co-Authors: Omar Šerý, Naim Akhtar Khan, Jana Janoutová, Laura Ewerlingová, Alice Hálová, Jan Lochman, Vladimir Janout, Vladimir J. Balcar
    Abstract:

    CD36 gene encodes a membrane glycoprotein (type B scavenger receptor) present on the surface of many types of cells and having multiple cellular functions ranging from angiogenesis to Gustatory Perception of fatty acids. Using a case control genetic association approach we have analyzed selected single nucleotide polymorphisms (SNP's) in a total of 859 patients with Alzheimer's disease (AD) and controls and have identified the allele A in rs3211892 polymorphism of CD36 gene as significantly increasing the risk of AD. Additionally we have investigated, in the same sample of control subjects and patients, SNP's in ApoE gene and confirmed that the previously identified AD-associated SNP's indeed increased the risk and decreased the age of onset of AD as reported by others earlier. Based on the current knowledge of CD36 biochemistry we propose that the AD risk-imparting variants of CD36 alter cholesterol homeostasis, oxidation stress or induce pathological inflammatory cascades. The SNP rs3211892 has previously been associated with heart disease and other conditions but the present study is the first to identify a significant association between variations in CD36 gene and the risk of Alzheimer's disease.

  • cell mechanisms of Gustatory lipids Perception and modulation of the dietary fat preference
    Biochimie, 2014
    Co-Authors: Gado Dramane, Simon Akpona, Philippe Besnard, Naim Akhtar Khan
    Abstract:

    Abstract Dietary lipids are usually responsible of several metabolic disorders. Recent compelling evidences suggest that there is a sixth taste modality, destined for the detection of oro-Gustatory fats. The lipid-binding glycoprotein CD36, expressed by circumvallate papillae (CVP) of the mouse tongue, has been shown to be implicated in oro-Gustatory Perception of dietary lipids. We demonstrate that linoleic acid (LA) by activating sPLA2, cPLA2 and iPLA2 via CD36, produced arachidonic acid (AA) and lyso-phosphatidylcholine (Lyso-PC) which triggered Ca2+ influx in CD36-positive taste bud cells (TBC), purified from mouse CVP. LA induced the production of Ca2+ influx factor (CIF). CIF, AA and Lyso-PC exerted different actions on the opening of store-operated Ca2+ (SOC) channels, constituted of Orai proteins and regulated by STIM1, a sensor of Ca2+ depletion in the endoplasmic reticulum. We observed that CIF and Lyso-PC opened Orai1 channels whereas AA-opened Ca2+ channels were composed of Orai1/Orai3. STIM1 was found to regulate LA-induced CIF production and opening of both kinds of Ca2+ channels. Furthermore, Stim1−/− mice lost the spontaneous preference for fat, observed in wild-type animals. Our results suggest that fatty acid-induced Ca2+ signaling, regulated by STIM1 via CD36, might be implicated in oro-Gustatory Perception of dietary lipids and the spontaneous preference for fat. Other cell types are involved in, and external factors can influence this preference.

  • Cell signaling mechanisms of oro-Gustatory detection of dietary fat: advances and challenges.
    Progress in Lipid Research, 2013
    Co-Authors: Timothy A. Gilbertson, Naim Akhtar Khan
    Abstract:

    CD36 and two G-protein coupled receptors (GPCR), i.e., GPR120 and GPR40, have been implicated in the Gustatory Perception of dietary fats in rodents. These glycoproteins are coupled to increases in free intracellular Ca2+ concentrations, [Ca2+]i, during their activation by dietary long-chain fatty acids (LCFA). The transient receptor potential type M5 (TRPM5) channel, activated by [Ca2+]i, participates in downstream signaling in taste bud cells (TBC). The mice, knocked-out for expression of CD36, GPR120, GPR40 or TRPM5 have a reduced spontaneous preference for fat. The delayed rectifying K+ (DRK) channels believed to lie downstream of these receptors are also important players in fat taste transduction. The trigeminal neurons by triggering increases in [Ca2+]i may influence the taste signal to afferent nerve fibers. Why are there so many taste receptor candidates for one taste modality? We discuss the recent advances on the role of CD36, GPR120, GPR40, TRPM5 and DRK channels, in signal transduction in TBC. We shed light on their cross-talk and delineate their roles in obesity as a better understanding of the molecular mechanisms behind their regulation could eventually lead to new strategies to fight against this condition.

  • obesity alters the Gustatory Perception of lipids in the mouse plausible involvement of lingual cd36
    Journal of Lipid Research, 2013
    Co-Authors: Michael Chevrot, Arnaud Bernard, Deborah Ancel, Marjorie Buttet, C Martin, Souleymane Abdoulazize, Jeanfrancois Merlin, Helene Poirier, Isabelle Niot, Naim Akhtar Khan
    Abstract:

    A relationship between orosensory detection of dietary lipids, regulation of fat intake, and body mass index was recently suggested. However, involved mechanisms are poorly understood. Moreover, whether obesity can directly modulate preference for fatty foods remains unknown. To address this question, exploration of the oral lipid sensing system was undertaken in diet-induced obese (DIO) mice. By using a combination of biochemical, physiological, and behavioral approaches, we found that i) the attraction for lipids is decreased in obese mice, ii) this behavioral change has an orosensory origin, iii) it is reversed in calorie-restricted DIO mice, revealing an inverse correlation between fat preference and adipose tissue size, iv) obesity suppresses the lipid-mediated downregulation of the lipid-sensor CD36 in circumvallate papillae, usually found during the refeeding of lean mice, and v) the CD36-dependent signaling cascade controlling the intracellular calcium levels ([Ca(2+)]i) in taste bud cells is decreased in obese mice. Therefore, obesity alters the lipid-sensing system responsible for the oral Perception of dietary lipids. This phenomenon seems to take place through a CD36-mediated mechanism, leading to changes in eating behavior.

Gro V. Amdam - One of the best experts on this subject based on the ideXlab platform.

  • rnai mediated double gene knockdown and Gustatory Perception measurement in honey bees apis mellifera
    Journal of Visualized Experiments, 2013
    Co-Authors: Ying Wang, Gro V. Amdam, Nicholas Baker
    Abstract:

    This video demonstrates novel techniques of RNA interference (RNAi) which downregulate two genes simultaneously in honey bees using double-stranded RNA (dsRNA) injections. It also presents a protocol of proboscis extension response (PER) assay for measuring Gustatory Perception. RNAi-mediated gene knockdown is an effective technique downregulating target gene expression. This technique is usually used for single gene manipulation, but it has limitations to detect interactions and joint effects between genes. In the first part of this video, we present two strategies to simultaneously knock down two genes (called double gene knockdown). We show both strategies are able to effectively suppress two genes, vitellogenin (vg) and ultraspiracle (usp), which are in a regulatory feedback loop. This double gene knockdown approach can be used to dissect interrelationships between genes and can be readily applied in different insect species. The second part of this video is a demonstration of proboscis extension response (PER) assay in honey bees after the treatment of double gene knockdown. The PER assay is a standard test for measuring Gustatory Perception in honey bees, which is a key predictor for how fast a honey bee's behavioral maturation is. Greater Gustatory Perception of nest bees indicates increased behavioral development which is often associated with an earlier age at onset of foraging and foraging specialization in pollen. In addition, PER assay can be applied to identify metabolic states of satiation or hunger in honey bees. Finally, PER assay combined with pairing different odor stimuli for conditioning the bees is also widely used for learning and memory studies in honey bees.

  • Gustatory Perception and fat body energy metabolism are jointly affected by vitellogenin and juvenile hormone in honey bees
    PLoS Genetics, 2012
    Co-Authors: Ying Wang, Erin Fennern, Colin S. Brent, Gro V. Amdam
    Abstract:

    Honey bees (Apis mellifera) provide a system for studying social and food-related behavior. A caste of workers performs age-related tasks: young bees (nurses) usually feed the brood and other adult bees inside the nest, while older bees (foragers) forage outside for pollen, a protein/lipid source, or nectar, a carbohydrate source. The workers' transition from nursing to foraging and their foraging preferences correlate with differences in Gustatory Perception, metabolic gene expression, and endocrine physiology including the endocrine factors vitellogenin (Vg) and juvenile hormone (JH). However, the understanding of connections among social behavior, energy metabolism, and endocrine factors is incomplete. We used RNA interference (RNAi) to perturb the gene network of Vg and JH to learn more about these connections through effects on gustation, gene transcripts, and physiology. The RNAi perturbation was achieved by single and double knockdown of the genes ultraspiracle (usp) and vg, which encode a putative JH receptor and Vg, respectively. The double knockdown enhanced Gustatory Perception and elevated hemolymph glucose, trehalose, and JH. We also observed transcriptional responses in insulin like peptide 1 (ilp1), the adipokinetic hormone receptor (AKHR), and cGMP-dependent protein kinase (PKG, or "foraging gene" Amfor). Our study demonstrates that the Vg-JH regulatory module controls changes in carbohydrate metabolism, but not lipid metabolism, when worker bees shift from nursing to foraging. The module is also placed upstream of ilp1, AKHR, and PKG for the first time. As insulin, adipokinetic hormone (AKH), and PKG pathways influence metabolism and gustation in many animals, we propose that honey bees have conserved pathways in carbohydrate metabolism and conserved connections between energy metabolism and Gustatory Perception. Thus, perhaps the bee can make general contributions to the understanding of food-related behavior and metabolic disorders.

Natasha Thorne - One of the best experts on this subject based on the ideXlab platform.

  • Gustatory Perception and behavior in drosophila melanogaster
    Current Biology, 2005
    Co-Authors: Hubert Amrein, Natasha Thorne
    Abstract:

    The sense of taste is essential for the survival of virtually all animals. Considered a ‘primitive sense' and present in the form of chemotaxis in many bacteria, taste is also a sense of sophistication in humans. Regardless, taste behavior is a crucial activity for the world's most abundant (insects) and most successful (mammals) inhabitants, providing a means of discrimination between nutrient-rich substrates, such as sugars and amino acids, from harmful, mostly bitter-tasting chemicals present in many plants. In this review, we present an update on progress in understanding taste Perception in the model fruit fly Drosophila melanogaster . An introduction to the fly's taste system will be presented first, followed by a description of relevant behavioral assays developed to quantify taste Perception at the organismal level and a short overview of electrophysiological studies performed on taste cells. The focal point will be the recent molecular-genetic investigations of the Gustatory receptor ( Gr ) genes, which is complemented by a comparison between Drosophila and mammalian taste Perception and transduction. Finally, we provide a perspective on the future of Drosophila taste research, including three specific proposals that seem uniquely applicable to this exquisite model system and cannot, at least currently, be pursued elsewhere.

  • Gustatory Perception and behavior in Drosophila melanogaster
    Current Biology, 2005
    Co-Authors: Hubert Amrein, Natasha Thorne
    Abstract:

    The sense of taste is essential for the survival of virtually all animals. Considered a 'primitive sense' and present in the form of chemotaxis in many bacteria, taste is also a sense of sophistication in humans. Regardless, taste behavior is a crucial activity for the world's most abundant (insects) and most successful (mammals) inhabitants, providing a means of discrimination between nutrient-rich substrates, such as sugars and amino acids, from harmful, mostly bitter-tasting chemicals present in many plants. In this review, we present an update on progress in understanding taste Perception in the model fruit fly Drosophila melanogaster. An introduction to the fly's taste system will be presented first, followed by a description of relevant behavioral assays developed to quantify taste Perception at the organismal level and a short overview of electrophysiological studies performed on taste cells. The focal point will be the recent molecular-genetic investigations of the Gustatory receptor (Gr) genes, which is complemented by a comparison between Drosophila and mammalian taste Perception and transduction. Finally, we provide a perspective on the future of Drosophila taste research, including three specific proposals that seem uniquely applicable to this exquisite model system and cannot, at least currently, be pursued elsewhere. ©2005 Elsevier Ltd. All rights reserved.

Scott D Pletcher - One of the best experts on this subject based on the ideXlab platform.

  • Gustatory and metabolic Perception of nutrient stress in drosophila
    Proceedings of the National Academy of Sciences of the United States of America, 2015
    Co-Authors: Nancy J Linford, Jennifer Ro, Brian Y Chung, Scott D Pletcher
    Abstract:

    Sleep loss is an adaptive response to nutrient deprivation that alters behavior to maximize the chances of feeding before imminent death. Organisms must maintain systems for detecting the quality of the food source to resume healthy levels of sleep when the stress is alleviated. We determined that Gustatory Perception of sweetness is both necessary and sufficient to suppress starvation-induced sleep loss when animals encounter nutrient-poor food sources. We further find that blocking specific dopaminergic neurons phenocopies the absence of Gustatory stimulation, suggesting a specific role for these neurons in transducing taste information to sleep centers in the brain. Finally, we show that Gustatory Perception is required for survival, specifically in a low nutrient environment. Overall, these results demonstrate an important role for Gustatory Perception when environmental food availability approaches zero and illustrate the interplay between sensory and metabolic Perception of nutrient availability in regulating behavioral state.

  • re patterning sleep architecture in drosophila through Gustatory Perception and nutritional quality
    PLOS Genetics, 2012
    Co-Authors: Nancy J Linford, Tammy P Chan, Scott D Pletcher
    Abstract:

    Organisms perceive changes in their dietary environment and enact a suite of behavioral and metabolic adaptations that can impact motivational behavior, disease resistance, and longevity. However, the precise nature and mechanism of these dietary responses is not known. We have uncovered a novel link between dietary factors and sleep behavior in Drosophila melanogaster. Dietary sugar rapidly altered sleep behavior by modulating the number of sleep episodes during both the light and dark phase of the circadian period, independent of an intact circadian rhythm and without affecting total sleep, latency to sleep, or waking activity. The effect of sugar on sleep episode number was consistent with a change in arousal threshold for waking. Dietary protein had no significant effect on sleep or wakefulness. Gustatory Perception of sugar was necessary and sufficient to increase the number of sleep episodes, and this effect was blocked by activation of bitter-sensing neurons. Further addition of sugar to the diet blocked the effects of sweet Gustatory Perception through a Gustatory-independent mechanism. However, Gustatory Perception was not required for diet-induced fat accumulation, indicating that sleep and energy storage are mechanistically separable. We propose a two-component model where Gustatory and metabolic cues interact to regulate sleep architecture in response to the quantity of sugar available from dietary sources. Reduced arousal threshold in response to low dietary availability may have evolved to provide increased responsiveness to cues associated with alternative nutrient-dense feeding sites. These results provide evidence that Gustatory Perception can alter arousal thresholds for sleep behavior in response to dietary cues and provide a mechanism by which organisms tune their behavior and physiology to environmental cues.

Marie Guiraud - One of the best experts on this subject based on the ideXlab platform.

  • aversive Gustatory learning and Perception in honey bees
    Scientific Reports, 2018
    Co-Authors: Marie Guiraud, Lucie Hotier, Martin Giurfa, Maria Gabriela De Brito Sanchez
    Abstract:

    Taste Perception allows discriminating edible from non-edible items and is crucial for survival. In the honey bee, the Gustatory sense has remained largely unexplored, as tastants have been traditionally used as reinforcements rather than as stimuli to be learned and discriminated. Here we provide the first characterization of antennal Gustatory Perception in this insect using a novel conditioning protocol in which tastants are dissociated from their traditional food-reinforcement role to be learned as predictors of punishment. We found that bees have a limited Gustatory repertoire via their antennae: they discriminate between broad Gustatory modalities but not within modalities, and are unable to differentiate bitter substances from water. Coupling Gustatory conditioning with blockade of aminergic pathways in the bee brain revealed that these pathways are not restricted to encode reinforcements but may also encode conditioned stimuli. Our results reveal unknown aspects of honey bee gustation, and bring new elements for comparative analyses of Gustatory Perception in animals.