http://chemse.oxfordjournals.org Chemical Senses - RSS feed of current issue 1464-3553 November 2009 Chemical Senses 0379-864X http://chemse.oxfordjournals.org/cgi/content/short/34/9/NP?rss=1 Thu, 15 Oct 2009 00:37:02 PDT info:doi/10.1093/chemse/bjp075 Oxford University Press 9 34 NP 2009-11-01 NP Standing Material http://chemse.oxfordjournals.org/cgi/content/short/34/9/NP-a?rss=1 Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp076 Oxford University Press 9 34 NP 2009-11-01 NP Cover http://chemse.oxfordjournals.org/cgi/content/short/34/9/NP-b?rss=1 Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp077 Oxford University Press 9 34 NP 2009-11-01 NP Standing Material http://chemse.oxfordjournals.org/cgi/content/short/34/9/NP-c?rss=1 Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp078 Oxford University Press 9 34 NP 2009-11-01 NP Standing Material http://chemse.oxfordjournals.org/cgi/content/short/34/9/733?rss=1 Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp074 Oxford University Press 9 34 734 2009-11-01 733 In this issue http://chemse.oxfordjournals.org/cgi/content/short/34/9/735?rss=1 Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp072 Oxford University Press 9 34 737 2009-11-01 735 Commentary http://chemse.oxfordjournals.org/cgi/content/short/34/9/739?rss=1 The objective of this study was to develop a semantically labeled hedonic scale (LHS) that would yield ratio-level data on the magnitude of liking/disliking of sensation equivalent to that produced by magnitude estimation (ME). The LHS was constructed by having 49 subjects who were trained in ME rate the semantic magnitudes of 10 common hedonic descriptors within a broad context of imagined hedonic experiences that included tastes and flavors. The resulting bipolar scale is statistically symmetrical around neutral and has a unique semantic structure. The LHS was evaluated quantitatively by comparing it with ME and the 9-point hedonic scale. The LHS yielded nearly identical ratings to those obtained using ME, which implies that its semantic labels are valid and that it produces ratio-level data equivalent to ME. Analyses of variance conducted on the hedonic ratings from the LHS and the 9-point scale gave similar results, but the LHS showed much greater resistance to ceiling effects and yielded normally distributed data, whereas the 9-point scale did not. These results indicate that the LHS has significant semantic, quantitative, and statistical advantages over the 9-point hedonic scale.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp054 Oxford University Press 9 34 751 2009-11-01 739 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/753?rss=1 People are often able to reliably detect a mixture of 2 or more odorants, even if they cannot reliably detect the individual mixture components when presented individually. This phenomenon has been called mixture agonism. However, for some mixtures, agonism among mixture components is greater in barely detectable mixtures than in more easily detectable mixtures (level dependence). Most studies that have used rigorous methods have focused on simple, 2-component (binary) mixtures. The current work takes the next logical step to study detection of 3-component (ternary) mixtures. Psychometric functions were measured for 5 unmixed compounds and for 3 ternary mixtures of these compounds (2 of 5, forced-choice method). Experimenters used air dilution olfactometry to precisely control the duration and concentration of stimuli and used gas chromatography/mass spectrometry to verify vapor-phase concentrations. For 2 of the 3 mixtures, agonism was approximately additive in general agreement with similar work on binary mixtures. A third mixture was no more detectable than the most detectable component, demonstrating a lack of agonism. None of the 3 mixtures showed evidence of level dependence. Agonism may be common in ternary mixtures, but general rules of mixture interaction have yet to emerge. For now, detection of any mixture must be measured empirically.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp062 Oxford University Press 9 34 761 2009-11-01 753 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/763?rss=1 In moths, the components of the female pheromone blend are detected in the male antennae by pheromone olfactory receptor neurons (Ph-ORNs) expressing narrowly tuned olfactory receptors. Responses to sex pheromones have generally been thought to be independent from the odorant background. However, interactions between pheromone components and plant volatiles have been reported at behavioral and detection levels. To document the mechanisms of such interactions, we analyzed Ph-ORN responses of Spodoptera littoralis to the main pheromone component, Z9E11-14:Ac, in the presence of 4 monoterpenes. To mimic natural contexts in which plant odors and pheromone emanate from different sources, the 2 stimuli were presented with different temporal patterns and from independent sources. Linalool reversibly reduced the firing response to Z9E11-14:Ac and produced an off effect. Geraniol and geranyl and linalyl acetates reduced the responses to Z9E11-14:Ac with a longer time course. Pulses of linalool over prolonged pheromone stimulation resulted in a discontinuous firing activity. Pulses of pheromone were better separated over a background of linalool, compared with odorless air. The data confirm that plant compounds may modulate the intensity and the temporal coding by Ph-ORNs of pheromone information. This modulation might positively affect mate location at high pheromone density especially nearby a pheromone source.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp060 Oxford University Press 9 34 774 2009-11-01 763 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/775?rss=1 Exposure to flavors in the amniotic fluid and mother's milk derived from the maternal diet has been shown to modulate food preferences and neophobia of young animals of several species. Aim of the experiment was to study the effects of pre- and postnatal flavor exposure on behavior of piglets during (re)exposure to this flavor. Furthermore, we investigated whether varying stress levels, caused by different test settings, affected behavior of animals during (re)exposure. Piglets were exposed to anisic flavor through the maternal diet during late gestation and/or during lactation or never. Piglets that were prenatally exposed to the flavor through the maternal diet behaved differently compared with unexposed pigs during reexposure to the flavor in several tests, suggesting recognition of the flavor. The differences between groups were more pronounced in tests with relatively high stress levels. This suggests that stress levels, caused by the design of the test, can affect the behavior shown in the presence of the flavor. We conclude that prenatal flavor exposure affects behaviors of piglets that are indicative of recognition and that these behaviors are influenced by stress levels during (re)exposure.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp063 Oxford University Press 9 34 787 2009-11-01 775 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/789?rss=1 The P2X ionotropic purinergic receptors, P2X2 and P2X3, are essential for transmission of taste information from taste buds to the gustatory nerves. Mice lacking both P2X2 and P2X3 purinergic receptors (P2X2/P2X3^Dbl–/–) exhibit no taste-evoked activity in the chorda tympani and glossopharyngeal nerves when stimulated with taste stimuli from any of the 5 classical taste quality groups (salt, sweet, sour, bitter, and umami) nor do the mice show taste preferences for sweet or umami, or avoidance of bitter substances (Finger et al. 2005. ATP signaling is crucial for communication from taste buds to gustatory nerves. Science. 310[5753]:1495–1499). Here, we compare the ability of P2X2/P2X3^Dbl–/– mice and P2X2/P2X3^Dbl+/+ wild-type (WT) mice to detect NaCl in brief-access tests and conditioned aversion paradigms. Brief-access testing with NaCl revealed that whereas WT mice decrease licking at 300 mM and above, the P2X2/P2X3^Dbl–/– mice do not show any change in lick rates. In conditioned aversion tests, P2X2/P2X3^Dbl–/– mice did not develop a learned aversion to NaCl or the artificial sweetener SC45647, both of which are easily avoided by conditioned WT mice. The inability of P2X2/P2X3^Dbl–/– mice to show avoidance of these taste stimuli was not due to an inability to learn the task because both WT and P2X2/P2X3^Dbl–/– mice learned to avoid a combination of SC45647 and amyl acetate (an odor cue). These data suggest that P2X2/P2X3^Dbl–/– mice are unable to respond to NaCl or SC45647 as taste stimuli, mirroring the lack of gustatory nerve responses to these substances.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp068 Oxford University Press 9 34 797 2009-11-01 789 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/799?rss=1 Mice lacking the purinergic receptors, P2X2 and P2X3 (P2X2/P2X3^Dbl–/–), exhibit essentially no tastant-evoked activity in the chorda tympani and glossopharyngeal nerves and substantial loss of tastant-evoked behavior as measured in long-term intake experiments. To assess whether the residual chemically driven behaviors in these P2X2/P2X3^Dbl–/– mice were attributable to postingestive detection or oropharyngeal detection of the compounds, we used brief access lickometer tests to assess the behavioral capabilities of the P2X2/P2X3^Dbl–/– animals. The P2X2/P2X3^Dbl–/– mice showed avoidance to high levels (10 mM quinine and 10–30 mM denatonium benzoate) of classical "bitter"-tasting stimuli in 24-h, 2-bottle preference tests but minimal avoidance of these substances in the lickometer tests, suggesting that the strong avoidance in the intake tests was largely mediated by post-oral chemosensors. Similarly, increases in consumption of 1 M sucrose by P2X2/P2X3^Dbl–/– mice in long-term intake tests were not mirrored by increases in consumption of sucrose in lickometer tests, suggesting that sucrose detection in these mice is mediated by postingestive consequences. In contrast, in brief access tests, P2X2/P2X3^Dbl–/– mice avoided citric acid and hydrochloric acid at the same concentrations as their wild-type counterparts, indicating that these weak acids activate oropharyngeal chemoreceptors.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp069 Oxford University Press 9 34 808 2009-11-01 799 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/809?rss=1 Previous human sensory evaluation studies have shown that glutathione (GSH) enhances deliciousness, accompanied by thickness, mouthfulness, and continuity feeling, which is known as "kokumi" in Japanese, in an umami solution containing monosodium glutamate and 5'-inosine monophosphate (IMP). We conducted behavioral and electrophysiological experiments to explore possible interactions of taste effectiveness between GSH and umami substances in mice. The 2-bottle preference test revealed that the mice preferred GSH at concentrations ranging from 1 to 10 mM. When GSH was added to IMP or a mixture of IMP and monopotassium glutamate (MPG), the mice showed increased preference for these solutions over the individual IMP or the binary mixture of IMP and MPG in both short-term and long-term tests. The addition of GSH to MPG, however, did not increase preference. Neural responses of the chorda tympani and glossopharyngeal nerves to the mixture of IMP and GSH showed synergism, whereas synergism was not observed in the mixture of MPG and GSH in either taste nerve. Another behavioral study with the use of the conditioned taste aversion paradigm showed that aversions to MPG generalized moderately to GSH, but aversions to GSH did not generalize to MPG. The present study suggests that GSH enhances preference for umami solutions containing 5'-ribonucleotide rather than glutamate. On the basis of these results, we discuss possible receptors involved for the action of GSH.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp070 Oxford University Press 9 34 818 2009-11-01 809 ARTICLES http://chemse.oxfordjournals.org/cgi/content/short/34/9/819?rss=1 Surprisingly little is known about the effects of big-city air pollution on olfactory function and even less about its effects on the intranasal trigeminal system, which elicits sensations like burning, stinging, pungent, or fresh and contributes to the overall chemosensory experience. Using the Sniffin’ Sticks olfactory test battery and an established test for intranasal trigeminal perception, we compared the olfactory performance and trigeminal sensitivity of residents of Mexico City, a region with high air pollution, with the performance of a control population from the Mexican state of Tlaxcala, a geographically comparable but less polluted region. We compared the ability of 30 young adults from each location to detect a rose-like odor (2-phenyl ethanol), to discriminate between different odorants, and to identify several other common odorants. The control subjects from Tlaxcala detected 2-phenyl ethanol at significantly lower concentrations than the Mexico City subjects, they could discriminate between odorants significantly better, and they performed significantly better in the test of trigeminal sensitivity. We conclude that Mexico City air pollution impairs olfactory function and intranasal trigeminal sensitivity, even in otherwise healthy young adults.

]]> Thu, 15 Oct 2009 00:37:03 PDT info:doi/10.1093/chemse/bjp071 Oxford University Press 9 34 826 2009-11-01 819 ARTICLES