2-hexenal--z-isomer and 3-hexen-1-ol

Volatile components in fresh leaves are involved in the regulation of many stress responses, such as insect damage, fungal infection and high temperature. However, the potential function of volatile components in hyperosmotic response is largely unknown. Here, we found that 7-day hyperosmotic treatment specifically led to the accumulation of (Z)-3-hexen-1-ol, (E)-2-hexenal and methyl salicylate. Transcriptome and qRT-PCR analyses suggested the activation of linolenic acid degradation and methyl salicylate processes. Importantly, exogenous (Z)-3-hexen-1-ol pretreatment dramatically enhanced the hyperosmotic stress tolerance of tea plants and decreased stomatal conductance, whereas (E)-2-hexenal and methyl salicylate pretreatments did not exhibit such a function. qRT-PCR analysis revealed that exogenous ABA induced the expressions of related enzyme genes, and (Z)-3-hexen-1-ol could up-regulate the expressions of many DREB and RD genes. Moreover, exogenous (Z)-3-hexen-1-ol tremendously induced the expressions of specific LOX and ADH genes within 24 h. Taken together, hyperosmotic stress induced (Z)-3-hexen-1-ol accumulation in tea plant via the activation of most LOX, HPL and ADH genes, while (Z)-3-hexen-1-ol could dramatically enhance the hyperosmotic stress tolerance via the decrease of stomatal conductance and MDA, accumulation of ABA and proline, activation of DREB and RD gene expressions, and probably positive feedback regulation of LOXs and ADHs. KEY MESSAGE: Hyperosmotic stress induced (Z)-3-hexen-1-ol accumulation in Camellia sinensis via the up-regulation of most LOX, HPL and ADH genes, while (Z)-3-hexen-1-ol could dramatically enhance the hyperosmotic stress tolerance via the decrease of stomatal conductance, accumulation of proline, activation of DREB and RD gene expressions, and probably positive feedback regulation of LOXs and ADHs.

Topics: Aldehydes; Camellia sinensis; Hexanols; Nicotiana; Stress, Physiological; Volatile Organic Compounds; Water

Green leaf volatiles (GLVs) have been reported to play an important role in the host-locating behavior of several folivores that feed on angiosperms. However, next to nothing is known about how the green leafhopper, Empoasca vitis, chooses suitable host plants and whether it detects differing emission levels of GLV components among genetically different tea varieties. Here we found that the constitutive transcript level of the tea hydroperoxide lyase (HPL) gene CsiHPL1, and the amounts of (Z)-3-hexenyl acetate and of total GLV components are significantly higher in tea varieties that are susceptible to E. vitis (Enbiao (EB) and Banzhuyuan (BZY)) than in varieties that are resistant to E. vitis (Changxingzisun (CX) and Juyan (JY)). Moreover, the results of a Y-tube olfactometer bioassay and an oviposition preference assay suggest that (Z)-3-hexenyl acetate and (Z)-3-hexenol offer host and oviposition cues for E. vitis female adults. Taken together, the two GLV components, (Z)-3-hexenol and especially (Z)-3-hexenyl acetate, provide a plausible mechanism by which tea green leafhoppers distinguish among resistant and susceptible varieties. Future research should be carried out to obtain the threshold of the above indices and then assess their reasonableness. The development of practical detection indices would greatly improve our ability to screen and develop tea varieties that are resistant to E. vitis.

Topics: Acetates; Aldehydes; Animals; Camellia sinensis; Cues; Food Chain; Hemiptera; Herbivory; Hexanols; Plant Proteins

Several green leaf volatiles have anxiolytic/antidepressant properties and attenuate adrenocortical stress response in rodents. However, it remains unknown whether a mixture of cis-3-hexenol and trans-2-hexenal so-called 'green odor (GO)' affects fear-associated post-traumatic stress disorder (PTSD)-like behavior. In the present study, fear memory of the initial conditioning stimulus was stably maintained by weekly presentation of conditioned tone. Examination of open field behavior, acoustic startle response, prepulse inhibition, and immobility in the forced swim test for 2 weeks after initial conditioning revealed that conditioned rats sustained anxiety, enhanced startle response, hypervigilance, depression-like behavior, and hypocortisolism, which is consistent with PTSD symptoms. Daily, not acute, GO presentation facilitated fear extinction and reduced PTSD-like behavioral and endocrinal responses. To further investigate the mechanism of effect of GO, we examined the effect of paroxetine (a selective serotonin reuptake inhibitor), p-chlorophenylalanine (PCPA, an irreversible serotonin synthesis inhibitor), alone or in combination of GO on PTSD-like phenotype. The alleviative effects of GO were masked by simultaneous paroxetine administration. PCPA-induced serotonin depletion abolished the effects of GO. Our results suggest that daily GO presentation facilitates fear extinction and prevents development of PTSD-like symptoms.

Topics: Aldehydes; Animals; Conditioning, Psychological; Disease Models, Animal; Drug Evaluation, Preclinical; Exploratory Behavior; Extinction, Psychological; Fear; Fenclonine; Hexanols; Male; Motor Activity; Paroxetine; Phenotype; Prepulse Inhibition; Psychotropic Drugs; Random Allocation; Rats, Sprague-Dawley; Reflex, Startle; Stress Disorders, Post-Traumatic

The black citrus aphid, also known as the tea aphid, (Toxoptera aurantii Boyer) attacks economically important crops, including tea (Camellia sinensis (L.) O. Kuntze). In the current study, silica sol-gel formulations were screened to find one that could carry and release C. sinensis plant volatiles to lure black citrus aphids in a greenhouse. The common plant volatile trans-2-hexen-1-al was used as a model molecule to screen for suitable sol-gel formulations. A zNose (Electronic Sensor Technology, Newbury Park, CA) transportable gas chromatograph was used to continuously monitor the volatile emissions. A sol-gel formulation containing tetramethyl orthosilicate and methyltrimethoxysilane in an 8:2 (vol:vol) ratio was selected to develop a slow-release dispenser. The half-life of trans-2-hexen-1-al in the sol-gel dispenser increased slightly with the volume of this compound in the dispenser. Ten different volatiles were tested in the sol-gel dispenser. Alcohols of 6-10 carbons had the longest half-lives (3.01-3.77 d), while esters of 6-12 carbons had the shortest (1.53-2.28 d). Release of these volatiles from the dispensers could not be detected by the zNose after 16 d (cis-3-hexenyl acetate) to 26 d (3,7-dimethylocta-1,6-dien-3-ol). In greenhouse experiments, trans-2-hexen-1-al and cis-3-hexen-1-ol released from the sol-gel dispensers attracted aphids for ≍17 d, and release of these volatiles could not be detected by the zNose after ≍24 d. The sol-gel dispensers performed adequately for the slow release of plant volatiles to trap aphids in the greenhouse.

Topics: Acyclic Monoterpenes; Aldehydes; Animals; Aphids; Camellia sinensis; Hexanols; Insect Control; Monoterpenes; Volatile Organic Compounds

Attraction of the soybean pod borer, Leguminivora glycinivorella (Matsumura), an economically important pest of soybean, to nine plant volatiles, alone or combined with two kinds of synthetic sex pheromone, ((E,E)-8,10-dodecadienyl acetate (EE8,10-12:Ac), or a blend of EE8,10-12:Ac and (E)-10-dodecenyl acetate in a 10:1 ratio), was evaluated in field trapping experiments in a soybean field in Harbin, China. By themselves, the plant volatiles (dose) linalool (0.1 mg), (Z)-3-hexenyl acetate (0.1 mg), and geraniol (0.1 mg, 1.0 mg) were weakly attractive to L. glycinivorella males, but significantly reduced mean catches when higher doses were combined with pheromones. Conversely, (E)-2-hexenal, benzaldehyde, and phenylacetaldehyde were not attractive to L. glycinivorella males at any dose tested, but significantly increased mean catch when certain doses were combined with the binary pheromone blend. Other plant volatiles, such as (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, and (E)-2-hexenyl acetate, were unattractive on their own, but significantly reduced mean catch of L. glycinivorella males when certain doses were combined with the pheromones. These results suggest that efficacy of pheromone-baited traps for survey and monitoring of L. glycinivorella male moths may be enhanced by the addition of specific plant volatiles and that the relative dose is critical.

Topics: Acetaldehyde; Acetates; Aldehydes; Animals; Benzaldehydes; Hexanols; Lepidoptera; Male; Sex Attractants

The medial prefrontal cortex (mPFC) is involved in stimulus perception, attentional control, emotional behavior, and the stress response. These functions are thought to be mediated by the infralimbic (IL) and prelimbic (PL) subregions of mPFC; however, few studies have examined the roles of IL and PL cortices in olfactory cognition. In the present study, we investigated the acute effects of two odors, 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) and a mixture of cis-3-hexenol and trans-2-hexenal (green odor: GO), on behavioral responses and IL and PL neuronal activities using extracellular single-unit recordings in a freely moving rat. We found that the total number of spike firings in IL and PL neurons did not change with 10s presentation of odors. TMT presentation induced significant changes in burst firing activity in IL and PL neurons, while GO presentation induced changes in burst firing only in IL neurons. In the temporal profile of the firing activity of IL neurons, TMT exposure induced transient activation and GO exposure induced sustained activation. Those of PL neurons showed sustained activation during TMT exposure and transient activations during GO exposure. GO exposure induced a stretch-attend posture, whereas TMT exposure induced immobility. Furthermore, multiple regression analysis indicated that the property of the odor and neuronal activities of IL and PL regions were correlated with behavioral responses. These findings reveal that olfaction-related neurons exist in IL and PL regions, and that the neurons in these regions might temporarily encode odor information in order to modulate motor outputs by tuning firing properties in the early stage of cognition according to the odor property.

Topics: Aldehydes; Analysis of Variance; Animals; Behavior, Animal; Electrophysiology; Hexanols; Limbic System; Male; Motor Activity; Neurons; Odorants; Prefrontal Cortex; Rats; Rats, Wistar; Regression Analysis; Smell; Thiazoles

Green odor (GO), a mixture of cis-3-hexenol and trans-2-hexenal, attenuates stress responses and anxiety to psychological stressors in rodents; however, it remains unknown whether GO affects behavioral and stress responses to risk-related olfactory stimuli and actual noxious stimuli. The present study investigated the effects of green odor on behavioral and plasma adrenocorticotropic hormone (ACTH) responses to 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a component of fox feces, and electric footshock (FS) stress. When rats were simultaneously exposed to TMT and GO, they showed decreases in immobility and plasma ACTH levels compared with TMT alone. GO exposure after TMT increased immobility, but blocked the elevation of plasma ACTH levels compared with rats exposed to distilled water after TMT. This means that GO presentation during TMT attenuated the TMT-induced behavioral response and GO presentation during and after TMT inhibited TMT-induced elevation of plasma ACTH levels. Furthermore, electric FS-induced plasma ACTH elevations were attenuated by simultaneous GO and FS exposure. GO presentation after FS attenuated plasma ACTH elevations and fecal responses. These findings reveal that GO has alleviating effects on olfactory stimulus- and noxious stimulus-induced behavioral and endocrinal responses.

Topics: Adrenocorticotropic Hormone; Aldehydes; Animals; Anti-Anxiety Agents; Anxiety; Behavior, Animal; Disease Models, Animal; Drug Therapy, Combination; Electric Stimulation; Eliminative Behavior, Animal; Hexanols; Male; Olfactory Perception; Rats; Rats, Wistar; Stress, Psychological; Thiazoles

Chronic maternal stress during pregnancy results in the "prenatally stressed" offspring displaying behavioral and neuroendocrine alterations that persist into adulthood. We investigated how inhalation of green odor (a mixture of equal amounts of trans-2-hexenal and cis-3-hexenol) by stressed dams might alter certain indices of prenatal stress in their offspring. These indices were depression-like behavior (increased immobility time in the forced-swim test) and acute restraint stress-induced changes in hypothalamo-pituitary-adrenocortical (HPA) axis activity [plasma corticosterone (CORT) and ACTH levels and the number of Fos-immunoreactive cells in the hypothalamic paraventricular nucleus (an index of neuronal activity)]. Pregnant rats were exposed to restraint stress for 60 min/day for 10 days (gestational days 10-19). The prenatally stressed offspring exhibited significant increases in depression-like behavior and in restraint stress-induced ACTH, CORT, and Fos responses, unless their dam had been exposed to green odor. The behavioral effect of the odor was also seen in offspring that were fostered by unstressed dams. The results obtained in the dams themselves were as follows. In vehicle-exposed stressed dams, but not in green odor-exposed ones, total body and adrenal weights were significantly decreased or increased, respectively. Depression-like behavior was not observed in the vehicle-exposed stressed dams themselves. Green odor inhalation prevented the impairment of maternal behavior induced by restraint stress. Thus, exposure of dams to stress may affect both the fetal brain and fetal HPA axis, and also maternal behavior, leading to altered behavioral and neuroendocrine responses in the offspring. Such effects may be prevented by the stressed dams inhaling green odor.

Topics: Administration, Inhalation; Adrenal Glands; Adrenocorticotropic Hormone; Aldehydes; Animals; Body Weight; Corticosterone; Depression; Female; Hexanols; Male; Maternal Behavior; Paraventricular Hypothalamic Nucleus; Pregnancy; Prenatal Exposure Delayed Effects; Proto-Oncogene Proteins c-fos; Psychotropic Drugs; Random Allocation; Rats; Rats, Wistar; Restraint, Physical; Stress, Psychological

Although various emotional behaviors and activation of the hypothalamic-pituitary-adrenal (HPA) axis of rats are induced by the exposure of 2,5-dihydro-2,4,5-trimethylthiazoline: TMT, a component of fox odor, these odor-induced responses are influenced by the external environment. Our previous study demonstrated that exposure to green odor, a mixture of cis-3-hexenol and trans-2-hexenal, attenuated stress-induced elevation of the plasma ACTH level in rats. The present study investigated the effect of TMT or green odor on emotional behavior and the HPA axis stress response with or without the influence of environmental novelty. We exposed rats to TMT or green odor in "familiar" or "unfamiliar" environments and compared the various responses, including fear-related behaviors, non-defensive behaviors and plasma ACTH concentrations. TMT induced enhanced freezing behavior, reduced exploration behavior and elevations in plasma ACTH concentrations in two environmental conditions. Comparing TMT-induced responses in an unfamiliar environment with the familiar environment showed that environmental novelty enhanced TMT-induced fear-related behaviors and elevations of plasma ACTH concentrations. These results revealed that TMT causes fear and stress responses in both familiar and unfamiliar environments, although the novelty of an unfamiliar environment enhances these TMT-induced responses. On the other hand, green odor did not induce any responses in either environment. These findings indicate that odor-induced responses are influenced by the surrounding environment.

Topics: Adrenocorticotropic Hormone; Aldehydes; Animals; Environment; Exploratory Behavior; Fear; Hexanols; Male; Motor Activity; Odorants; Rats; Rats, Wistar; Stress, Psychological; Thiazoles

In the present study, on rats, a quantitative analysis of Fos protein immunohistochemistry was performed as a way of investigating the effects of inhalation of green odor (a mixture of equal amounts of trans-2-hexenal and cis-3-hexenol) on the neuronal activations in stress-related forebrain regions induced by acute and repeated stress. Rats were exposed to restraint stress for 90 min each day for 1, 2, 4, 7, or 11 consecutive days. The hypothalamic paraventricular nucleus (PVN), amygdala, hippocampus and paraventricular thalamic nucleus (PVT) were examined. Both acute and repeated restraint stress increased Fos-positive cells in the entire hypothalamic PVN, in the central and medial amygdala, and in PVT, although these responses declined upon repeated exposure to such stress. The stress-induced Fos responses were much weaker in rats that inhaled green odor during each day's restraint. No increases in Fos-positive cells were observed in the hippocampus in acutely stressed rats. The Fos-immunoreactive response to acute stress shown by the piriform cortex did not differ significantly between the vehicle+stress and green+stress groups. Green odor had inhibitory effects on the stress-induced corticosterone response, body-weight loss, and adrenal hypertrophy. These results suggest that in rats, green odor inhalation may, in an as yet unknown way, act on the brain to suppress activity in the neuronal networks involved in stress-related responses (such as activation of the hypothalamo-pituitary-adrenocortical axis and activation of the sympathetic nervous system, as well as stress-induced fear responses).

Topics: Administration, Inhalation; Aldehydes; Amygdala; Animals; Biomarkers; Cell Count; Corticosterone; Disease Models, Animal; Down-Regulation; Fear; Hexanols; Hippocampus; Hypothalamo-Hypophyseal System; Male; Midline Thalamic Nuclei; Odorants; Paraventricular Hypothalamic Nucleus; Pituitary-Adrenal System; Prosencephalon; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar; Restraint, Physical; Smell; Stress, Psychological; Weight Loss

We investigated whether inhalation of green odor (a mixture of equal amounts of trans-2-hexenal and cis-3-hexenol) prevents the skin-barrier disruption induced by chronic restraint stress in rats. To this end, transepidermal water loss (TEWL) was measured as an index of the disruption of skin-barrier function, whereas light- and electron-microscope examinations were performed to observe histological changes in the skin of the stressed animals. In addition, the effects on TEWL induced by chronic administration of a glucocorticoid, dexamethasone (DEX), were examined. Chronic restraint stress (8 h per day for 14 days) increased TEWL (vehicle + stress group). This effect (and the chronic stress-induced increase in adrenal weight) was prevented in rats that inhaled green odor at the beginning of each day's restraint (2 h each day for 14 days; green odor + stress group). Electron-microscope studies revealed that rats in the green odor + stress group possessed sufficient intercorneocyte lipids to create an effective skin barrier, although these had apparently been decreased in the vehicle + stress group. Daily administration of DEX for 14 days increased TEWL. The present results suggest that chronic stress-induced disruption of the skin barrier in rats can be reduced or prevented by green odor (possibly at least in part through an inhibitory effect on the stress-induced activation of the hypothalamo-pituitary-adrenocortical axis).

Topics: Aldehydes; Animals; Dexamethasone; Glucocorticoids; Hexanols; Male; Odorants; Rats; Rats, Wistar; Restraint, Physical; Skin; Smell; Stimulation, Chemical; Stress, Physiological; Water Loss, Insensible

We investigated volatile infochemicals possibly involved in location of the generalist predatory mite Neoseiulus californicus to plants infested with spider mites in a Y-tube olfactometer. The predators significantly preferred volatiles from lima bean leaves infested with Tetranychus urticae to uninfested lima bean leaves. Likewise, they were attracted to volatiles from artificially damaged lima bean leaves and those from T. urticae plus their visible products. Significantly more predators chose infested lima bean leaves from which T. urticae plus their visible products had been removed than artificially damaged leaves, T. urticae, and their visible products. These results suggest that N. californicus is capable of exploiting a variety of volatile infochemicals originating from their prey, from the prey-foodplants themselves, and from the complex of the prey and the host plants (e.g., herbivore-induced volatiles). We also investigated predator response to some of the synthetic samples identified as volatile components emitted from T. urticae-infested lima bean leaves and/or artificially damaged lima bean leaves. The predators were attracted to each of the five synthetic volatile components: linalool, methyl salicylate, (Z)-3-hexen-1-ol, (E)-2-hexenal, and (Z)-3-hexenyl acetate. The role of each volatile compound in prey-searching behavior is discussed.

Topics: Acetates; Acyclic Monoterpenes; Aldehydes; Animals; Chemotactic Factors; Female; Hexanols; Mites; Monoterpenes; Odorants; Phaseolus; Plant Leaves; Predatory Behavior; Salicylates; Smell; Tetranychidae; Volatilization

The equivalent mixture of cis-3-hexenol and trans-2-hexenal (hexenol/hexenal), 'green odor', is known to have a healing effect on the psychological damage caused by stress. Behavioral studies in humans and monkeys have revealed that hexenol/hexenal prevents the prolongation of reaction time caused by fatigue. In the present study, we investigated which brain regions are activated by the odor of hexenol/hexenal using positron emission tomography with alert monkeys. Regional cerebral blood flow (rCBF) in the prepyriform area (the primary olfactory cortex) was commonly increased by the passive application of odor: acetic acid, isoamylacetate or hexenol/hexenal. We observed rCBF increases in the orbitofrontal cortex (the secondary olfactory cortex) by these olfactory stimuli in two of three monkeys, and found no predominance of laterality of the activated hemisphere. Furthermore, rCBF increase in the cerebellum was observed in two of three monkeys, and the odor of acetic acid increased rCBF in the substantia innominata in all monkeys. In addition to these olfactory related regions, the anterior cingulate gyrus was activated by the odor of hexenol/hexenal. These findings suggest that the increase of rCBF in the anterior cingulate gyrus by the odor of hexenol/hexenal may contribute the healing effects of this mixture observed in the monkey.

Topics: Aldehydes; Animals; Brain Mapping; Cerebellum; Gyrus Cinguli; Hexanols; Macaca mulatta; Magnetic Resonance Imaging; Male; Odorants; Smell; Substantia Innominata; Tomography, Emission-Computed