Repetitive Olfactory Exposure to the Biologically Significant Steroid Androstadienone Causes a Hedonic Shift and Gender Dimorphie Changes in Olfactory-Evoked Potentials
Nassima Boulkroune, Liwei Wang, Amy March, Natalie Walker and Tim JC Jacob ; Neuropsychopharmacology (2007) 32, 1822-1829
The function of a sensory system is to transduce and relay sensory information in a constant and reproducible manner. However, in the olfactory processing of certain steroids this precept of sensory constancy does not appear to apply. Using threshold testing, psychometrics, and electrophysiological techniques, we investigated the effects of a repetitive exposure protocol on the response to androstadienone. Androstadienone is a steroid found in human secretions that has been widely proposed as a candidate for a human pheromone. The detection threshold, hedonic perception, and evoked potential response all changed following repetitive exposure to androstadienone and not to a control odorant, benzaldehyde. Furthermore, the exposure-dependent changes in evoked potentials exhibited a gender dimorphism in which there were changes in the later components of the evoked potentials specific to women. These components have been associated with cognitive and perceptual operations. This ‘learning’ to smell a compound found in sweat may be related to biological signaling.
On the nose: shared themes for the sensory and immune self.
Doherty PC. ; Nat Immunol. 2003 Nov: 4(11): 1043-5.
The immune system and the central nervous system operate in very different ways. but the dual use of the major histocompatibility complex D8+ T cell monitoring and pheromone presentation indicates some commonalities exist.
Sensory coding of pheromone signals in mammals.
Dulac C. ; Présentation Curr Opin Neurobiol. 2000 Aug; 10(4): 511-8.
The vomeronasal organ (VNO) of mammals plays an essential role in the detection of pheromones, chemical cues secreted by animals that elicit genetically programmed sexual and aggressive behaviors among conspecifics. The recent characterization of genes encoding molecular components of the VNO sensory response suggests that VNO neurons express a unique set of molecules to recognize and translate pheromone signals into neuronal electrical activity. Identification of these genes, which include putative pheromone receptor genes, has offered a new opportunity to uncover basic principles of pheromone sensory processing and important aspects of vomeronasal development.
How the olfactory system makes sense of scents.
Firestein S. ; Nature. 2001 Sep 13; 413(6852): 211-8.
The human nose is often considered something of a luxury, but in the rest of the animal world, from bacteria to mommals, detecting chemicals in the environment has been critical to the successful organism. An indication of the importance of olfactory systems is the significant proportion – as much as 4% – of the genomes of many higher eukaryotes that is devoted to encoding the proteins of smell. Growing interest in the detection of diverse compounds at single-molecule levels has made the olfactory system an important system for biological modelling.
[Pheromones: an underestimated communication signal in humans] (Article in French)
Frey J. ; Ann Biol Clin (Paris). 2003 May-Jun; 61(3): 275-8
The pheromones are molecules, mainly aliphatic acids, with or without perceptible odor, recognized by specific receptors, the stimulation of which induces neuroendocrine reactions and affects the individual behavior. Olfactory receptors are underexpressed in human, 70 % of genes have become nonfunctional pseudogenes. But the remaining function was tested and is able to induce emotional reactions corresponding to a non-verbal signal of social interactions. In the present study, we review the actual knowledge on the olfactory receptors. They belong to the G-protein-coupled-receptors. Their signal is transduced to the hypothalamic-pituitary-gonadal axis. Some HLA-based olfactory cues are shown with reference to recent experiments. The pathophysiological hypotheses are considered with respect to studies in anorexia nervosa and Alzheimer’s disease.
Identification of VIR-like Putative Pheromone Receptor Sequences in Non-human Primates. Characterization of VIR Pseudogenes in Marmoset, a Primate Species that Possesses an Intact Vomeronasal Organ
Dominique Giorgi and Sylvie Rouquier ; Chem. Senses 27: 529-537 2002
The vomeronasal organ (VNO) is responsible in terrestrial vertebrates for the sensory perception of some pheromones, chemicals that elicit characteristic behaviors among individuals of the same species. Two multigene families (V1R, V2R) that encode proteins with seven putative transmembrane domains that are expressed selectively in different neuron subsets of the VNO have been described in rodents. Pheromone-induced behaviors and a functional VNO have been described in a number of mammals, but this sensory organ seems absent in adult catarrhines and apes, including humans. Until now, only pseudogenes have been isolated in humans, except one putative V1R (hV1RL1) sequence expressed in the main olfactory epithelium. We sought to isolate V1R-like genes in a New World monkey species, the marmoset Callithrix jacchus, that possesses an intact VNO and for which pheromone-induced behavior has been well documented. Using library screening approaches, we have identified five different sequences that exhibit characteristic features of V1R sequences, but that are non-functional pseudogenes. In an attempt to sort out functional V1R genes, we next cloned by polymerase chain reaction (PCR) the primate orthologues of hV1RL1. This approach was successful for gorilla, chimpanzee and orangutan, but not for the other species, including marmoset, probably because these species are too divergent from humans. Chimpanzee and orangutan V1RL1 genes are pseudogenes, whereas the gorilla counterpart is potentially functional. These observations raise the possibility that the V1R family has evolved in such a manner in mammals that every species that relies on a VNO-mediated sensory function possesses its own set of functional vomeronasal genes.
[Human and animal vomeronasal systems in health and disease] (Article in Russian)
Gulimova VI ; Arkh Patol. 2002 Jul-Aug; 64(4): 52-9
The vomeronasal organ (VO) or the second olfactory organ has the form of paired epithelial pockets at the base of the nasal septum. In animals it has various functions including reception of pheromones mediating sexual, parental and social behavior. Human VO was considered to be rudimental until the last decade of the XXth century. Since then it was found to be present almost in every adult individual and was proved to be functional. The paper provides new facts on the occurrence of VO in man and animals, analyzes possible consequences of plastic surgery of the nose and considers some vomeronasal abnormalities, their diagnosis and treatment.
Synthetic musks in environmental samples: indicator compounds with relevant properties for environmental monitoring.
Kallenborn R, Gatermann R, Rimkus GG ; J Environ Monit. 1999 Aug; 1(4): 7ON-74N
Synthetic musks (nitro and palycyclic musks) are a group of chemicals offering a wide range of important properties for environmental monitoring programs. They are produced as odorous chemicals and added to a wide variety of perfumes, toiletry products and other household products. As such, they are directly applied in cosmetic products or in washed textiles to the human body in considerable concentrations and accumulate owing to dermal resorption. In addition, synthetic musks also enter the environment via waste water treatment. Several polycyclic musks are chiral. By using chiral gas chromatographic methods, it is possible to determine the enantiomeric ratio and assess their bioavailability. Although an comprehensive quality assurance program must be followed during the analysis of synthetic musks in environmental samples, the determination of these compounds is not very demanding and can be carried out by a standard analytical laboratory specialising in trace analysis of organic pollutants. Owing to the pheromone-like behavior of some synthetic musks, the induction of receptors in olfactory systems should be investigated. For HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran, e.g., Galaxolide), three-dimensional structural similarities with androstenone (5 alpha-androst-16-en-3-one), a mammalian steroid pheromone, were found, which support the hypothesis of HHCB as an artificial pheromone. Owing to their environmental abundance, their relation to human activities and their potential for pheromone-like environmental behavior, synthetic musks are especially valuable as future indicator chemicals for environmental monitoring.
Pheromones, vomeronasal function, and gender-specific behavior.
Keverne EB ; Cell. 2002 Mar 22: 108(6): 735-8
The striking behavioral phenotypes of mice lacking the TRP2 ion channel have highlighted the importance of the vomeronasal organ in gender-specific sexual behavior.
Assessment of olfactory function and androstenone odor thresholds in humans with or without functional occlusion of the vomeronasal duct.
Knecht M, Lundstrom JN, Witt M, Huttenbrink KB, Heilmann S, Hummel! T.
Behav Neurosci. 2003 Dec: 117(6): 1135-41
To obtain information on the possible role of the vomeronasal duct (VND) in odor perception and human pheromone detection, the present study investigated different aspects of olfactory function, including thresholds for androstenone in adults with or without detectable VNDs. The study also examined correlations between detection thresholds of androstenone odor and general olfactory function. Subjects’ olfaction was assessed with tests for odor identification, odor discrimination, and phenyl ethyl alcohol odor threshold. Measurements were performed on 1 side only. with and without covering the VND. Subjects with or without detectable VNDs did not differ in olfactory sensitivity or androstenone odor thresholds. A small but significant correlation was found between detection thresholds of androstenone and general olfactory function. Finally, covering of the VND did not affect olfactory function or androstenone sensitivity. Results suggest that the human VND does not play a major role in sensitivity toward odorants or the perception of androstenone.
[The human vomeronasal organ] (Article in German)
Knecht M, Witt M, Abolmaali N ,Huttenbrink KB, Hummel T. ; Nervenarzt. 2003 Oct: 74(10): 858-62
Odors influence human behavior. The perception of so-called pheromones is frequently mentioned in the context of a functional vomeronasal organ. Vomeronasal ducts con be detected in approximately half of the population. Its functionality, still a matter of debate, seems to be unlikely, at least after birth. It is easily conceivable that pheromone-induced changes in behavior are mediated through receptors in the human olfactory epithelium.
Relaxed selective pressure on an essential component of pheromone transduction in primate evolution.
Liman ER, Innan H. ; Proc Natl Acad Sci USA. 2003 Mar 18; 100(6): 3328-32
The vomeronasal organ (VNO) detects pheromones in many vertebrate species but is likely to be vestigial in humans. TRPC2 (TRP2), a gene that is essential for VNO function in the mouse, is a pseudogene in humans. Because TRPC2 is expressed only in the VNO, the loss of selective pressure on this gene can serve as a molecular marker for the time at which the VNO became vestigial. By analyzing sequence data from the TRPC2 gene of 15 extant primate species, we provide evidence that the VNO was most likely functional in the common ancestor of New World monkeys and Old World monkeys and apes, but then became vestigial in the common ancestor of Old World monkeys and apes. We propose that, at this point in evolution, other modalities, notably the development of color vision, may have largely replaced signaling by pheromones.
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