Olfactory Discrimination and Transient Mood Change in Young Men and Women: Variation by Season,Mood State,and Time of Day

Odor performance varies by clinical state and gender, though little is known about its variation by season or time of day. Many odors, including lavender, induce transient mood changes. This study explored discrimination differences between various lavender oil blends and their effects on transient mood in the morning and evening in depressed and nondepressed adults. We also determined seasonal influences on these measures. A total of 169 subjects, 98 women and 71 men (mean age ± SD, 19.3 ± 1.6 y) participated, with different subjects studied at different times of the year. The Beck Depression Inventory (BDI) classified subjects as depressed (score ≥10; N = 57) or nondepressed (score <10; N = 112). In the discrimination test, subjects compared pairs of two different lavender oil blends or a control. Transient change in mood was assessed by the Profile of Mood States (POMS) after each trial of five lavender blends interspersed by three control odors. Tests were conducted in the morning (08:00–10:00 h) and evening (18:00–20:00 h). In all subjects, discrimination was significantly better for some odor pairs than for others, thus demonstrating test specificity. Discrimination was better overall in the fall than winter/spring and better in depressed than nondepressed subjects for specific odor pairs. No significant gender or time-of-day differences in discriminability were detected. There were, however, significant group differences in transient mood profiles. Current depressed state affected mood response, with lavender increasing anger in depressed subjects only. In addition, depressed subjects and men, whether or not depressed, exhibited diurnal mood variation, with better mood in the evening; the former group also showed more evening energy. All subjects were more confused in the morning than evening. Season also affected transient mood; winter/spring-tested subjects reported more vigor than fall-tested subjects. In addition, summer-tested subjects showed more tension in the morning, whereas fall-tested subjects showed the opposite pattern in the evening. In all subjects, lavender increased fatigue, tension, confusion, and total mood disturbance, and it decreased vigor. The study showed that both chronobiological (seasonal and time-of-day) and clinical factors modify discrimination and mood response to odors. Brief lavender odor presentation may serve as a nonphotic method for altering mood in young depressed and nondepressed adults particularly during the fall, a time of heightened discriminability.     

Ciliated olfactory receptor neurons in goldfish (Carassius auratus) partially survive nerve axotomy,rapidly regenerate and respond to amino acids

Electro-olfactogram (EOG) recordings in response to amino acid stimulation were made from both control and experimental olfactory mucosae following unilateral axotomy. The recorded EOG amplitudes, amino acid stimulus relative effectiveness and dose-response relations for control and experimental mucosae were comparable in all pre- and postoperative recordings. Semi-thin investigations of olfactory mucosae showed degeneration of olfactory receptors but indicated that intact receptors were also present. SEM of olfactory mucosae revealed that ciliated receptor cells were present in both axotomized and control sides on postoperative days, whereas microvillous receptors completely degenerated and did not regenerate until 7 weeks post axotomy. The present findings along with previous behavioral observations suggest at least three possible sources of the EOGs recorded from the experimental olfactory mucosae following olfactory nerve transection: (1) young olfactory receptor neurons whose axons had not yet reached the region of the transected olfactory nerve; (2) newly-emerged olfactory receptor neurons; and (3) olfactory receptor neurons that had not degenerated.Abbreviations EOG electro-olfactogram - SEM scanning electron microscopy (micrograph)     

Immunolocalization of pheromone-binding protein and general odorant-binding protein in olfactory sensilla of the silk moths Antheraea and Bombyx

The distribution of odorant-binding proteins among olfactory sensilla of three moth species was studied by immuno-electron microscopy. Two polyclonal antisera were used in a post-embedding labelling protocol on sections of cryo-substituted antennae. The first was directed against the pheromone-binding protein (PBP) of Antheraea polyphemus, the second against the general odorant-binding protein (GOBP) of the same species. Immunoblots showed that these antisera were highly specific; both antisera did, however, cross-react with related proteins in the related species A. pernyi, and in the bombycid moth B. mori. PBP and GOBP were localized only in olfactory sensilla trichodea and sensilla basiconica, the principal site being the sensillum lymph surrounding the sensory dendrites. In the males of all three species, the pheromone-sensitive long sensilla trichodea exclusively contained PBP. the majority of the sensilla basiconica in both sexes in these species contained GOBP; these sensilla are known to respond to plant and other general odours. Some sensilla were not labelled by either antiserum; presumably, these held an odorantbinding protein of a different subfamily. Never were PBP and GOBP co-localized in the same sensillum. Two observations deserve special attention: (1) PBP was also found in a few sensilla in females, and (2) in B. mori, where the long sensilla trichodea have a different functional specificity in males (pheromone) and females (plant odours), the expression of the odorant-binding protein (males: PBP; females: GOBP) is similarly different. The distinct and complex distribution pattern of odorant-binding proteins supports the notion that these proteins participate in stimulus recognition.Dedicated to Professor Ya.A. Vinnikov on the occasion of his 85. birthdayThis work was partly supported by DFG grant ste 501/3-1.     

Chemical communication in heliothine moths

The chemical and temporal features of the sex-pheromone emitted by Heliothis virescens females are encoded by a diverse array of output pathways from the male-specific macroglomerular complex (MGC) in the antennal lobe. Most output neurons (29 out of 32) were activated by antennal stimulation with the principal component of the sex-pheromone blend of this species, (Z)-11-hexadecenal. Six neurons were excited solely by this component, 8 neurons also responded to the second essential blend component, (Z)-9-tetradecenal, and 14 neurons displayed equivalent responses to the two. Many neurons also effectively encoded the onset and duration of the stimulus. In one additional neuron, a prolonged excitatory response (synergism) was evoked only by the blend of the two components, indicating that some MGC neurons function as blend detectors.In contrast to the situation in Helicoverpa zea, none of the MGC neurons in H. virescens responded selectively to (Z)-9-tetradecenal, suggesting that these two noctuid species employ different neural strategies to encode information about their respective pheromone blends.Three MGC-output neurons responded selectively to (Z)-11-hexadecenyl acetate, an odorant released by some sympatric species that disrupts normal upwind flight to pheromones. Thus, changes in the attractant and deterrent chemical signals, as well as the physical features of these odor plumes, are encoded in the MGC across a diverse parallel array of output pathways to the protocerebrum.Abbreviations AL antennal lobe - AN antennal nerve - 16:AL hexadecanal - MGC macroglomerular complex - 14:AL tetradecanal - Z11-16:AL (Z) 11-hexadecenal - Z11-16:AC (Z) 11-hexadecenyl acetate - Z9-14:AL (Z) 9-tetradecenal - Z9-14:FO (Z) 9-tetradecenyl formate     

Intraepithelial blood vessels in the vomeronasal neuroepithelium of the rat

Summary Epithelial-vascular relationships are established during the development of the vomeronasal neuroepithelium of the rat. Special attention is given to the fine structure of the endothelial wall of intra-epithelial vessels, to ultrastructural aspects of the neuronal-vascular relationships, and to the appearance of inclusion bodies in the neuronal cells adjacent to these vessels. The neuronal perikarya surrounding the blood vessels are filled with highly developed smooth endoplasmic reticulum. Possible functional implications of the vascularization of the neuroepithelium of the vomeronasal organ in mediating olfacto-endocrine relationships are discussed. It is suggested that the intra-epithelial blood vessels are at least supportive and nutritive in nature, while their implication in an olfacto-endocrine connection remains obscure.On sabattical leave: Visiting Professor, Department of Anatomy, University of Kentucky, Lexington, Ky., USA     

Pheromone-induced stimulation of inositol-trisphosphate formation in insect antennae is mediated by G-proteins

Summary Phospholipase C in the antennae of Periplaneta americana was stimulated by pheromones in a GTP-dependent manner. The enzyme activity was potentiated by hydrolysis-resistant analogs of GTP and decreased by GDP analogs. Guanine nucleotide binding regulatory proteins (G-proteins) in antennal preparations were identified by bacterial toxin-catalyzed ADP-ribosylation and immunoreactivity with antibodies of designed specificity. The stimulatory effect of pheromones on inositol phosphate formation was completely blocked by pertussis toxin suggesting that the pheromone action was mediated via specific G-proteins.Abbreviations G-protein guanine nucleotide-binding regulatory protein - IP ₃ inositol 1,4,5-trisphosphate - GTPS guanine-5-[thio]-triphosphate - GDPS guanine-5-[-thio]-diphosphate - NAD nicotinic acid adenine dinucleotide - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - DTT dithiothreitol - MOPS 3-(N-morpholino)propanesulfonic acid - PIPES piperazine-N,N-bis[2-ethanesulfonic acid] - DMSO dimethyl-sulfoxide     

Representation of binary pheromone blends by glomerulus-specific olfactory projection neurons

An outstanding challenge in olfactory neurobiology is to explain how glomerular networks encode information about stimulus mixtures, which are typical of natural olfactory stimuli. In the moth Manduca sexta, a species-specific blend of two sex-pheromone components is required for reproductive signaling. Each component stimulates a different population of olfactory receptor cells that in turn target two identified glomeruli in the macroglomerular complex of the males antennal lobe. Using intracellular recording and staining, we examined how responses of projection neurons innervating these glomeruli are modulated by changes in the level and ratio of the two essential components in stimulus blends. Compared to projection neurons specific for one component, projection neurons that integrated information about the blend (received excitatory input from one component and inhibitory input from the other) showed enhanced ability to track a train of stimulus pulses. The precision of stimulus-pulse tracking was furthermore optimized at a synthetic blend ratio that mimics the physiological response to an extract of the females pheromone gland. Optimal responsiveness of a projection neuron to repetitive stimulus pulses therefore appears to depend not only on stimulus intensity but also on the relative strength of the two opposing synaptic inputs that are integrated by macroglomerular complex projection neurons.     

Intensity and the ratios of compounds in the scent of snapdragon flowers affect scent discrimination by honeybees (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Floral scent is used by pollinators during foraging to identify and discriminate among flowers. The ability to discriminate among scents may depend on both scent intensity and the ratios of the concentrations of the volatile compounds of a complex mixture rather than on the presence of a few compounds. We used four scent-emitting cultivars of snapdragon (Antirrhinum majus) to test this hypothesis by examining the ability of honeybees to differentiate among their scents. Each cultivar produced three monoterpenes (myrcene, E--ocimene, and linalool) and five phenylpropanoids (methylbenzoate, acetophenone, dimethoxytoluene, cis-methylcinnamate, and trans-methylcinnamate). Cultivars were reliably classified by their scents in a canonical discriminant analysis. Honeybees were unable to discriminate among the scents of flowers of the same cultivar in our assay. The ability of honeybees to discriminate among the scents of different cultivars was a function of the intensity of the floral scent. Discrimination was also correlated to the distance among the scents described by the discriminant analysis; the cultivars that had the greatest differences observed in the discriminant analysis were the easiest to discriminate. Our results show that honeybees are capable of using all of the floral volatiles to discriminate subtle differences in scent.