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Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressants, but the mechanisms by which they influence behavior are only partially resolved. Adult hippocampal neurogenesis is necessary for some of the responses to SSRIs, but it is unknown whether the mature dentate gyrus granule cells (mature DG GCs) also contribute. We deleted Serotonin 1A receptor (5HT1AR; a receptor required for the SSRI response) specifically from DG GCs and found that the effects of the SSRI fluoxetine on behavior and the Hypothalamic-Pituitary-Adrenal (HPA) axis were abolished. By contrast, mice lacking 5HT1ARs only in young adult born granule cells (abGCs) showed normal fluoxetine responses. Importantly, 5HT1AR deficient mice engineered to express functional 5HT1ARs only in DG GCs responded to fluoxetine, indicating that 5HT1ARs in DG GCs are sufficient to mediate an antidepressant response. Taken together, these data indicate that both mature DG GCs and young abGCs must be engaged for an antidepressant response.

Smell is the oldest sense of living species on our planet and has allowed communication between species from the beginning of life on earth. Odor has always fascinated mankind even in prehistorical times and the use of scented materials is documented since early history. Materials used were extracts from odorous natural products until the advent of organic chemistry. Progress in analytical methods allowed the isolation and structure identification of odor impact compounds from natural extracts and subsequent syntheses made it possible to produce these compounds on an industrial scale for use in many applications of modern perfumery.

Infant rats must learn to identify their mother’s diet-dependent odor. Once learned, maternal odor controls pups’ approach to the mother, their social behavior and nipple attachment. Here we present a review of the research from four different laboratories, which suggests that neural and behavioral responses to the natural maternal odor and neonatal learned odors are similar. Together, these data indicate that pups have a unique learning circuit relying on the olfactory bulb for neural plasticity and on the hyperfunctioning noradrenergic locus coeruleus flooding the olfactory bulb with norepinephrine to support the neural changes. Another important factor making this system unique is the inability of the amygdala to become incorporated into the infant learning circuit. Thus, infant rats appear to be primed in early life to learn odors that will evoke approach responses supporting attachment to the caregiver.

Recent results suggest that a negative ERP potential emerges not only on error trials, but is also found after correct responses. There is broad evidence that this component is generated in the anterior cingulate cortex (ACC). The present study aimed to explore the influence of working memory demands on the evaluation process probably reflected by the negative potential. To this purpose, a modified continuous performance task (CPT) was used, with variations of the delay between cues and imperative stimuli. Data were analyzed using conventional averaging techniques as well as source localization with LORETA (low resolution brain electromagnetic tomography). Results suggest a significant effect of working memory delay on the amplitude of the post-response negative ERP component. Its source was located in the anterior cingulate cortex, with the exact location being dependent upon working memory demands. The results support the notion of a general response evaluation system reflected by a post-response negative component. The findings of a working memory dependent modification of this potential suggest a functional link between the medial frontal cortex and the lateral frontal regions primarily involved in working memory processing.

The 3-methyl-4-(tricyclo[5.2.1.02,6]dec-4-en-8-ylidene)butan-2-ols (=Fleursandol®; rac-10), a new class of sandalwood odorants, were synthesized in their enantiomerically pure forms by use of tricyclo[5.2.1.02,6]dec-4-en-8-ones 17 and ent-17 and (tetrahydro-2H-pyran-2-yl)-protected 4-bromo-3-methylbutan-2-ols 22 and ent-22 as starting materials (Schemes 2–4). Only four of 16 possible stereoisomers of rac-10 possess the typical, very pleasant, long-lasting sandalwood odor (Table 1). The (2S,3R,4E,1′R,2′R,6′R,7′R)-isomer ent-10a is by far the most important representative, with an odor threshold of 5 μg/l in H2O.

The odorous trace constituent iso-β-bisabolol (4) was isolated from East Indian and Western Australian sandalwood oil and synthesized by using the (E/Z)-triene 12 (iso-γ-bisabolene) as a key intermediate. Only one of four stereoisomeric forms of 4, (6R,7R)-4a, is odor active, having a strong floral, muguet-like, very pleasant scent.

Peroxynitrite formation in vivo is implicated in numerous human diseases and there is considerable interest in the use of antioxidants and natural products such as thiols as “peroxynitrite scavengers”. We therefore investigated the effects of a recently identified constituent of onions, 3-mercapto-2-methylpentan-1-ol (3-MP), for its ability to inhibit peroxynitrite-mediated processes in vitro and using cultured human cells and compared its effectiveness against glutathione. 3-MP significantly inhibited peroxynitrite-mediated tyrosine nitration and inactivation of α 1 -antiproteinase to a greater extent than glutathione at each concentration tested (15–500 μM). 3-MP also inhibited peroxynitrite-induced cytotoxicity, intracellular tyrosine nitration, and intracellular reactive oxygen species generation in human HepG2 cells in culture to a greater extent than glutathione. These data suggest that 3-MP has the potential to act as an inhibitor of ONOO − -mediated processes in vivo and that the antioxidant action of 3-MP deserves further study.

3-Mercapto-2-methylpentan-1-ol was first detected in a complex thermally processed flavor and finally isolated from raw onions. The chemical structure of this new compound was identified by MS and (1)H NMR measurement and synthesis of the proposed structure. Sensory evaluation at different concentrations indicated that the flavor quality is strongly dependent on concentration. At low concentration (0.5 ppb) a pleasant meat broth, sweaty, onion, and leek-like odor can be perceived. On the basis of some isolation experiments and volatiles occurring in raw onions, a formation pathway is proposed. As one intermediate 3-mercapto-2-methylpentanal, another new strong flavor compound, was suggested. The presence of this compound in raw onions was confirmed by synthesis and comparison of MS and chromatographic data.

The essential oil produced from the heartwood of Santalum album L. was analyzed using GC/MS. Forty-four constituents were identified: one monoterpene and 43 sesquiterpenes. 2,10-Bisaboladien-6-ol (= β-bisabolol/epi-β-bisabolol) was one of the trace compounds found in east Indian sandalwood oil. Chiral GC analysis showed that besides the main stereoisomer, which possessed an (R,R)-configuration, all three other isomers were also present.

In an extract of peanut butter, prepared by a Likens-Nickerson extraction, 16 alkyl-substituted 5,6-dihydro-4H-1,3,5-dithiazines were identified. Their structures were confirmed by specific synthesis.

Antidepressant drugs and psychotherapy combined are more effective in treating mood disorders than either treatment alone, but the neurobiological basis of this interaction is unknown. To investigate how antidepressants influence the response of mood-related systems to behavioral experience, we used a fear-conditioning and extinction paradigm in mice. Combining extinction training with chronic fluoxetine, but neither treatment alone, induced an enduring loss of conditioned fear memory in adult animals. Fluoxetine treatment increased synaptic plasticity, converted the fear memory circuitry to a more immature state, and acted through local brain-derived neurotrophic factor. Fluoxetine-induced plasticity may allow fear erasure by extinction-guided remodeling of the memory circuitry. Thus, the pharmacological effects of antidepressants need to be combined with psychological rehabilitation to reorganize networks rendered more plastic by the drug treatment.

Infant rats must learn to identify their mother’s diet-dependent odor. Once learned, maternal odor controls pups’ approach to the mother, their social behavior and nipple attachment. Here we present a review of the research from four different laboratories, which suggests that neural and behavioral responses to the natural maternal odor and neonatal learned odors are similar. Together, these data indicate that pups have a unique learning circuit relying on the olfactory bulb for neural plasticity and on the hyperfunctioning noradrenergic locus coeruleus flooding the olfactory bulb with norepinephrine to support the neural changes. Another important factor making this system unique is the inability of the amygdala to become incorporated into the infant learning circuit. Thus, infant rats appear to be primed in early life to learn odors that will evoke approach responses supporting attachment to the caregiver.

Infant rats must learn to identify their mother’s diet-dependent odor. Once learned, maternal odor controls pups’ approach to the mother, their social behavior and nipple attachment. Here we present a review of the research from four different laboratories, which suggests that neural and behavioral responses to the natural maternal odor and neonatal learned odors are similar. Together, these data indicate that pups have a unique learning circuit relying on the olfactory bulb for neural plasticity and on the hyperfunctioning noradrenergic locus coeruleus flooding the olfactory bulb with norepinephrine to support the neural changes. Another important factor making this system unique is the inability of the amygdala to become incorporated into the infant learning circuit. Thus, infant rats appear to be primed in early life to learn odors that will evoke approach responses supporting attachment to the caregiver.

The article contains sections titled: 1. Introduction 1.1. The Chemical Senses 1.2. Definition 1.3. History 1.4. Odor Descriptors, Odor Thresholds, Odor Value 1.4.1. Qualitative Measurements 1.4.2. Quantitative Measurements 1.4.2.1. Odor Threshold 1.4.2.2. Odor Value 1.5. Regulations and Labeling Requirements 1.5.1. Flavors 1.5.2. Fragrances 2. Single Fragrance and Flavor Compounds 2.1. Aliphatic Compounds 2.1.1. Hydrocarbons 2.1.2. Alcohols 2.1.3. Aldehydes and Acetals 2.1.4. Ketones 2.1.5. Acids and Esters 2.1.6. Miscellaneous Compounds 2.2. Acyclic Terpenes 2.2.1. Hydrocarbons 2.2.2. Alcohols 2.2.3. Aldehydes and Acetals 2.2.4. Ketones 2.2.5. Acids and Esters 2.2.5.1. Geranyl and Neryl Esters 2.2.5.2. Linalyl and Lavandulyl Esters 2.2.5.3. Citronellyl Esters 2.2.6. Miscellaneous Compounds 2.3. Cyclic Terpenes 2.3.1. Hydrocarbons 2.3.2. Alcohols and Ethers 2.3.3. Aldehydes and Ketones 2.3.4. Esters 2.3.5. Miscellaneous Compounds 2.4. Other Cycloaliphatic Compounds 2.4.1. Alcohols 2.4.2. Aldehydes 2.4.3. Ketones 2.4.4. Esters 2.5. Aromatic Compounds 2.5.1. Hydrocarbons 2.5.2. Alcohols and Ethers 2.5.3. Aldehydes and Acetals 2.5.4. Ketones 2.5.5. Esters of Araliphatic Alcohols and Aliphatic Acids 2.5.6. Aromatic Acids 2.5.7. Esters Derived from Aromatic and Araliphatic Acids 2.5.7.1. Benzoates 2.5.7.2. Phenyl acetates 2.5.7.3. Cinnamates 2.5.8. Miscellaneous Compounds 2.6. Phenols and Phenol Derivatives 2.6.1. Phenols, Phenyl Esters, and Phenyl Ethers 2.6.2. Phenol Alcohols and their Esters 2.6.3. Phenol Aldehydes 2.6.4. Phenol Ketones 2.6.5. Phenol Carboxylates 2.7. O- and O, S-Heterocycles 2.7.1. Cyclic Ethers 2.7.2. Lactones 2.7.3. Glycidates 2.7.4. Miscellaneous Compounds 2.8. N- and N, S-Heterocycles 3. Natural Raw Materials in the Flavor and Fragrance Industry 3.1. Introduction 3.2. Isolation of Natural Fragrance and Flavor Concentrates 3.2.1. Essential Oils 3.2.2. Extracts 3.3. Survey of Natural Raw Materials 4. Quality Control 5. Economic Aspects 6. Toxicology and Environmental Aspects

3-Mercapto-2-methylpentanol, a new powerful flavor compound, exhibits two stereocenters giving rise to two pairs of diastereomers. To determine differences in the sensory properties, all four diastereomers and enantiomers were stereo- and enantioselectively synthesized. A highly diastereoselective aldol reaction using a chiral auxiliary was one of the key steps in the synthesis. Further derivatization yielded the enantiopure compounds. Odor thresholds in air and water were determined.

Descriptions of compounds of natural origin for the purpose of adding odor and flavor to consumer goods date back to the beginning of history of man (Gilgamesch Epos, 1988). The history of the chemistry of flavor, i.e. the molecular knowledge of the flavor imparting compounds, should be considered as old as organic chemistry, the beginning of which is generally accepted as Wohler’s synthesis of urea (Wohler, 1828), so that a short review of the development of the chemistry of flavor compounds should not be limited to the last 30 years, even if this date coincides with the founding of the Flavor Group within the AGFC Section of ACS.