CAPSAICIN HEAT INTENSITY - CONCENTRATION, CARRIER, FAT LEVEL, AND SERVING TEMPERATURE EFFECTS

In a study of pungency in food systems, three carriers (water, cheese sauce, starch paste) with varying fat levels (none, low, medium, high), synthetic capsaicin concentrations (0.0, 0.4, 0.8, 1.3 ppm), and serving temperatures (25 and 38C) were formulated. Panelists evaluated sensory heat intensity over a 3-min interval. Time-intensity parameters (maximum intensity-MAX, time to maximum intensity-TMAX, and rate of release-RATE) were evaluated. Overall, intensity scores increased as capsaicin concentration increased. The increase was related to carrier and fat level. Water samples (0.4, 0.8, and 1.3 ppm) were perceived as more intense than cheese or starch samples at the same capsaicin level. Generally, increasing the fat level resulted in lower intensity scores. Warming samples increased RATE, the only parameter affected by temperature. The training method was effective when water was the carrier. However, physical or chemical interactions that occur in simple food systems may influence perceived pungency.     

MODELING OF SWEET, BITTER AND IRRITANT SENSATIONS AND THEIR INTERACTIONS ELICITED BY MODEL ICE WINES

Interactions between taste and irritant sensations elicited by model ice wine solutions were investigated, including the use of U and Γ′ models for predicting the perceived intensity of these sensory interactions. Fifteen solutions of varying ethanol and sugar concentrations representative of commercial ice wine values were evaluated in two trials by a trained sensory panel (n = 12) for perceived sweetness, bitterness and heat intensities. Sweetness perception of lower sugar‐concentration level in ice wine model solution was affected by ethanol concentration. The sweetness intensities of the sugar and ethanol mixtures are higher than the sweetness intensities of sugar solutions. The Γ′ index indicates a slight synergy between ethanol and sugar on sweetness perception. The bitterness intensities elicited by ethanol–sugar mixtures are lower than those elicited by unmixed ethanol solutions. The Γ′ index indicates inhibition of ethanol and sugar perception on bitterness perception. Suppression of heat sensation was found in model base wine solutions across sugar and ethanol concentrations.     

Differences in ratings of intensity and pleasantness for the capsaicin burn between chili likers and non-likers; implications for liking development

If liking for the chili burn is acquired, then the relationshipbetween ratings of burn intensity and pleasantness in chilinon-likers should be representative of the inital response patternto chili, and in chili likers, the final acquired response pattern.Close examination of these relationships may provide insightsinto the mechanisms that mediate liking development. The experimentreported here asked chili likers (frequent users) and non-likers(very infrequent users) to make burn intensity and pleasantnessjudgements for an ascending series of capsaicin concentrationsin an attempt to define the relationship between these variables.Non-likers were found to be indifferent to low to moderate burnintensities, which were liked by chili likers. Both groups dislikedstrong burn intensities. These data provide preliminary supportfor a model of liking development whereby initially indifferentresponses develop into liking responses apparently independentof sensory changes. ² Present address: CSIRO, Sensory Research Centre, PO Box 52.North Ryde, NSW 2113, Australia.     

Resiniferatoxin Hampers the Nocifensive Response of Caenorhabditis elegans to Noxious Heat,and Pathway Analysis Revealed that the Wnt Signaling Pathway is Involved

Resiniferatoxin (RTX) is a metabolite extracted from Euphorbia resinifera. RTX is a potent capsaicin analog with specific biological activities resulting from its agonist activity with the transient receptor potential channel vanilloid subfamily member 1 (TRPV1). RTX has been examined as a pain reliever, and more recently, investigated for its ability to desensitize cardiac sensory fibers expressing TRPV1 to improve chronic heart failure (CHF) outcomes using validated animal models. Caenorhabditis elegans (C. elegans) expresses orthologs of vanilloid receptors activated by capsaicin, producing antinociceptive effects. Thus, we used C. elegans to characterize the antinociceptive properties and performed proteomic profiling to uncover specific signaling networks. After exposure to RTX, wild-type (N2) and mutant C. elegans were placed on petri dishes divided into quadrants for heat stimulation. The thermal avoidance index was used to phenotype each tested C. elegans experimental group. The data revealed for the first time that RTX can hamper the nocifensive response of C. elegans to noxious heat (32 – 35 °C). The effect was reversed 6 h after RTX exposure. Additionally, we identified the RTX target, the C. elegans transient receptor potential channel OCR-3. The proteomics and pathway enrichment analysis results suggest that Wnt signaling is triggered by the agonistic effects of RTX on C. elegans vanilloid receptors.

     

Chili und der Capsaicinrezeptor TRPV1

Some like it hot – and spicy: Chili and the capsaicin receptor TRPV1 Since many hundred years, many people like to eat chili pepper containing the pungent ingredient capsaicin that is responsible for making the food hot and spicy. Capsaicin activates transient receptor potential TRPV1 channels that are predominantly expressed in sensory neurons involved in pain sensation. TRPV1 is a noxious heat sensor and can also be activated by protons and several animal toxins. Thus, TRPV1 is a polymodal sensor of multiple noxious stimuli that cause pain. TRPV1 functions as a nocisensor that detects chemical and thermal stimuli and transduces this stimulation into sensory nerve impulses which leads to the perception of pain. Inhibition of TRPV1 reduces or abolishes pain sensation. A strong activation of TRPV1 induces a long-lasting refractory period of the pain-detecting system (desensitization) and may even lead to an irreversible loss of TRPV1-expressing sensory neurons. It still remains unclear why many people love hot and spicy food, accompanied by a burning sensation in the mouth.     

Pharmacological evidence for the involvement of the cAMP cascade in sensory fatigue in Drosophila

Summary We have investigated the effect of systemic treatment with drugs that affect the cAMP cascade on the sensory response and sensory fatigue in an identified mechanosensory neuron of Drosophila. Forskolin, an activator of adenylate cyclase, decreases the sensory response of the neuron. H7, an inhibitor of protein kinase, inhibits sensory fatigue. Octopaminergic ligands facilitate sensory fatigue. These results, together with our previous neurogenetic analysis of sensory fatigue in Drosophila (Corfas and Dudai 1990), corroborate the hypothesis that the cAMP cascade is involved in the generation and modulation of sensory fatigue.Abbreviations ANP antero-notopleural (neuron) - CDMF chlordimeform - ISI interstimulus interval     

CONFIDENCE ELLIPSES APPLIED TO THE COMPARISON OF SENSORY PROFILES

Our experiment involved seven panels and six chocolates – five dark chocolates and one milk chocolate. The aim of the study was to compare the sensory profiles of the chocolates. A natural question to ask is “Did the panelists detect any differences among the five dark chocolates or did they systematically contrast them with the milk chocolate?” The scatter plot of the chocolates obtained by principal component analysis was useless to answer that question, because of the proximity of the points. To overcome that, we used confidence ellipses calculated using bootstrap. The originality of the study lies in the fact that we applied those ellipses to hierarchical multiple factor analysis (HMFA): among the seven panels, six were composed of trained professionals and the last one was composed of untrained students, and through that method, we managed to compare the two types of panels and balance the role of each trained panel. HMFA provides in a single scatter plot a representation of the six chocolates for each panel, the trained panels and all the panels. Confidence ellipses around each chocolate show that the combined panels – the six trained panels and also the untrained panel – differentiate the five dark chocolates. They also show how much larger the untrained panel's variability is than that of the trained panels, and how comparable are the trained panels' variability to each other.     

Anesthesiologists' practice patterns for treatment of postoperative nausea and vomiting in the ambulatory Post Anesthesia Care Unit

Background

Induction of the COX-2 isoenzyme appears to play a major role in the genesis of central sensitization after nociceptive stimulation. This study aimed to investigate the efficacy of a single, oral dose of the specific COX-2 inhibitor-valdecoxib in attenuating the central sensitization – induced secondary hyperalgesia in a heat/capsaicin pain model in healthy volunteers.

Methods

The study was a randomized, double blind, placebo controlled, crossover, single dose efficacy trial using 20 healthy volunteers. Two hours following placebo or 40 mg, PO valdecoxib, participants underwent skin sensitization with heat/capsaicin, as well as supra-threshold pain and re-kindling measurements according to an established, validated pain model. Subjects rated pain intensity and unpleasantness on a visual analog scale and the area of secondary hyperalgesia was serially mapped.

Results

The area of secondary hyperalgesia produced after 40 mg of valdecoxib was no different than that after placebo. Furthermore, there were no significantly relevant differences when volunteers were treated with valdecoxib or placebo in relation to either cold- or hot pain threshold or the intensity of pain after supra-threshold, thermal pain stimulation.

Conclusion

We demonstrated that a single, oral dose of valdecoxib when does not attenuate secondary hyperalgesia induced by heat/capsaicin in a cutaneous sensitization pain model in healthy volunteers.     

Effects of simulated heat waves on an experimental community of pepper plants,green peach aphids and two parasitoid species

Heat waves – extended periods of abnormally hot weather – are predicted to increase in severity and frequency under climate change. The severity of heat waves should impact communities and food webs through effects on performance of individual species and through changes in the strength of interactions between them. This study tested the effects of severity of simulated heat waves, with daily maxima of either 32°C or 40°C, on a tritrophic food web consisting of plants, Capsicum anuum, aphids, Myzus persicae and two parasitoids, Aphidius matricariae and Aphelinus abdominalis. Osmolarity of plant sap (concentration of dissolved solids) was highest under 40°C heat waves, suggesting the presence of secondary plant compounds involved with stress responses. Population growth of aphids was lower under heat waves (both 32°C and 40°C daily maxima), compared to environments with periodic hot days. Development time of parasitoids was longer under heat waves. Heat waves decreased the proportion of winged aphids in the population. When both parasitoid species were present, impacts on aphid populations were greater in heat wave environments than environments with periodic hot days. When either parasitoid species was by itself, heat waves did not affect the interaction between parasitoids and aphids. Numbers of A. matricariae were reduced in heat wave environments, whereas numbers of A. abdominalis were not. In addition to direct effects on individual species, we also obtained indirect evidence for the effects of heat waves on the bottom–up effects of plant stress compounds on herbivore performance, and on the strength of inter and intra‐specific competition. Our results demonstrate that heat waves could have important effects on community structure, and on important, community‐level processes such as intra‐guild interactions and trophic cascades.     

Differences in the chemesthetic subqualities of capsaicin, ibuprofen, and olive oil

Chemesthetic sensations elicited by ibuprofen, extra-virgin olive oil, and capsaicin were compared to quantify perceptual differences between known agonists of TRPA1 and TRPV1. Extra virgin olive oil contains a phenolic compound, oleocanthal, which is thought to share unique chemesthetic qualities with the nonsteroidal anti-inflammatory drug, ibuprofen. Pilot work suggested participants had difficulty distinguishing between multiple chemesthetic subqualities (e.g., burn, sting, itch, tickle, etc.) in a multiattribute rating task. Here, we assessed overall irritation via direct scaling, and a check all that apply task was used to collect information about chemesthetic subqualities over time. Replicated ratings were collected at discrete intervals using the generalized labeled magnitude scale to generate time-intensity curves; maximum intensity (Imax) and area under the curve were extracted for each participant. Intensity responses varied substantially across participants, and within a participant, the relationship was strongest between ibuprofen and olive oil. However, there were also positive, albeit weaker, correlations between capsaicin and ibuprofen and capsaicin and olive oil. The correlation found between olive oil and capsaicin may suggest the presence of unknown TRPV1 agonists in olive oil. This view was also supported by the qualitative data: capsaicin was described most often as burning and warm/hot, whereas ibuprofen was numbing and tickling. Olive oil shared characteristics with both capsaicin (warm/hot) and ibuprofen (tickle).     

Effect of capsaicin on thermosensitive receptors of the rat skinin vitro

The spike activity of cold- and heat-sensitive receptors was recorded in experiments on skin-nerve preparations (scrotum skin-n. pudendum) of male ratsin vitro. The effects of capsaicin in different concentrations (dilutions of 1·10⁻⁵, 1·10⁻⁶, and 1·10⁻⁷) on the background activity of these receptors and their sensitivity to thermal stimulation were studied. An excitatory effect of capsaicin in the concentrations of 1·10⁻⁵ and 1·10⁻⁶ on skin cold receptors, expressed as intensification of their background activity, was accompanied by complete suppression of their responses to cooling. Against the background of capsaicin in a lower concentration (1·10⁻⁷), some receptors preserved their responses to cooling, but the response intensity dropped, and the thresholds shifted toward lower temperatures. In heat receptors influenced by capsaicin, initial intensification of their responses to increased temperature and their subsequent desensitization to warming were observed.     

Altered nociceptive behavior and emotional contagion of pain in mouse models of autism

Individuals with autism spectrum disorder (ASD) have altered sensory processing but may ineffectively communicate their experiences. Here, we used a battery of nociceptive behavioral tests to assess sensory alterations in two commonly used mouse models of ASD, BTBR T⁺Itpr3^tf/J (BTBR), and fragile-X mental retardation-1 knockout (Fmr1-KO) mice. We also asked whether emotional contagion, a primitive form of empathy, was altered in BTBR and Fmr1 KO mice when experiencing pain with a social partner. BTBR mice demonstrated mixed nociceptive responses with hyporesponsivity to mechanical/thermal stimuli and intraplantar injections of formalin and capsaicin while displaying hypersensitivity on the acetic acid test. Fmr1-KO mice were hyposensitive to mechanical stimuli and intraplantar injections of capsaicin and formalin. BTBR and Fmr1-KO mice developed significantly less mechanical allodynia following intraplantar injections of complete Freund's adjuvant, while BTBR mice developed slightly more thermal hyperalgesia. Finally, as measured by the formalin and acetic acid writhing tests, BTBR and Fmr1-KO mice did not show emotional contagion of pain. In sum, our findings indicate that depending on the sensation, pain responses may be mixed, which reflects findings in ASD individuals.     

The entrainment of rhythmically discharging reticulospinal neurons of the eel by sensory nerve stimulation

Recordings made from decerebrated, paralyzed eels (Anguilla anguilla) producing rhythmical spinal motoneuronal activity showed that around 65% of identified reticulospinal units, belonging to the inferior reticular division, discharged rhythmically. The reticulospinal bursts, lasting from 300 up to 3000 ms, were in time with spinal motoneuronal bursting activity. In different fish the modal cycle period varied between 2 to 4 s and burst duration and firing frequency of each neuron showed large changes from cycle to cycle. Burst responses similar in form to those occurring spontaneously were evoked from reticular neurons when the ophthalmic nerve was stimulated regularly (intervals of 1 to 10 s) but the cycle period, firing frequency and burst duration were now more predictable. For stimulation intervals between 2 and 5 s, each ophthalmic nerve stimulus was normally followed by a burst from the reticulospinal neuron. The cycle period of the reticular rhythm then became equal to the interstimulus interval and the reticulospinal unit was entrained by the stimulus. Beyond this range of interstimulus intervals, complete entrainment was lost. We suggest that regular sensory input provides a powerful stabilising influence to rhythmically active motor systems in the brainstem and spinal cord.     

The effects of capsaicin and capsiate on energy balance: critical review and meta-analyses of studies in humans

Consumption of spicy foods containing capsaicin, the major pungent principle in hot peppers, reportedly promotes negative energy balance. However, many individuals abstain from spicy foods due to the sensory burn and pain elicited by the capsaicin molecule. A potential alternative for nonusers of spicy foods who wish to exploit this energy balance property is consumption of nonpungent peppers rich in capsiate, a recently identified nonpungent capsaicin analog contained in CH-19 Sweet peppers. Capsiate activates transient receptor potential vanilloid subtype 1 (TRPV1) receptors in the gut but not in the oral cavity. This paper critically evaluates current knowledge on the thermogenic and appetitive effects of capsaicin and capsiate from foods and in supplemental form. Meta-analyses were performed on thermogenic outcomes, with a systematic review conducted for both thermogenic and appetitive outcomes. Evidence indicates that capsaicin and capsiate both augment energy expenditure and enhance fat oxidation, especially at high doses. Furthermore, the balance of the literature suggests that capsaicin and capsiate suppress orexigenic sensations. The magnitude of these effects is small. Purposeful inclusion of these compounds in the diet may aid weight management, albeit modestly.     

Metabolism of capsaicinoids: Evidence for aliphatic hydroxylation and its pharmacological implications

A new metabolic oxidation pathway of capsaicin (N-[(4-hydroxy-3-methoxyphenyl)-methyl]-8-methyl-(E)-6-nonenamide), a major pungent and pharmacologically active principle of hot peppers, was investigated. Incubation of capsaicin with phenobarbital-induced rat liver postmitochondrial supernatant enriched with NADPH-generating system produced N-(4, 5-dihydroxy-3-methoxybenzyl)-(E)-6-nonenylamide and a more polar metabolite. The latter metabolite was spectrophotometrically and chromatographically identical to authentic ω-hydroxycapsaicin. This new metabolite was also detected in the urine of rabbits given capsaicin by gastric intubation. Other analogs of capsaicin, such as dihydrocapsaicin and nonivamide, also formed similar metabolites via aliphatic hydroxylation. When tested for antinociceptive activity as well as pungency, the above polar metabolites were found to be inactive while their parent compounds exhibited strong sensory effects. Capsaicin interacted irreversibly with hepatic drug metabolizing enzymes, thereby inhibiting their activity as indicated by prolongation of pentobarbital sleeping time in rats. Such inhibition of drug metabolism was not observed with ω-hydroxycapsaicin. These findings suggest that metabolism of capsaicinoids via hydroxylation of their side chains plays an important role in the detoxification of these pharmacologically active substances.     

FLAVOR PROPERTIES OF PLAIN SOYMILK*

A trained sensory panel was used to (1) establish terminology for describing flavor attributes of a wide range of “fresh” and processed soymilks (SMs); and (2) test the lexicon and describe the flavor properties of a wide range (n = 32) of plain SM samples. Twenty‐eight attributes were identified in the SMs studied. However, findings indicate that the main differences are a consequence largely of the presence of certain attributes that are either infrequently present or unique to a specific product. Thus, sensory evaluation of SM needs to include a review of samples to ensure that all attributes are documented prior to evaluation, or use a method that allows the addition of attributes during testing.