Olfactory system

Lancet D, Sadovsky E and Seidemann E 1993 Probability model for molecular recognition in biological receptor repertoires significance to the olfactory system Proc. Natl Acad. Sci. USA 90 3715-19... 

Odors are characterized by quaUty and intensity. Descriptive quaUties such as sour, sweet, pungent, fishy, and spicy are commonly used. Intensity is deterrnined by how much the concentration of the odoriferous substance exceeds its detection threshold (the concentration at which most people can detect an odor). Odor intensity is approximately proportional to the logarithm of the concentration. However, several factors affect the abiUty of an individual to detect an odor the sensitivity of a subject s olfactory system, the presence of other masking odors, and olfactory fatigue (ie, reduced olfactory sensitivity during continued exposure to the odorous substance). In addition, the average person s sensitivity to odor decreases with age. 

OT receptors are localized ia the brain hypothalamus, limbic system, cortex, striatum, olfactory system, and brain stem. In the periphery, OT is best known for its stimulation of uterine smooth muscle and the milk ejection reflex. Thr , Om ]oxytocin(l—8),... 

Air pollution principally affects the respiratory, circulatory, and olfactory systems. The respiratory system is the principal route of entry for air pollutants, some of which may alter the function of the lungs. 

Odors are perceived via the olfactory system, which is composed of two organs in the nose the olfactory epithelium, a very small area in the nasal system, and the trigeminal nerve endings, which are much more widely distributed in the nasal cavity (11). The olfactory epithelium is extremely sensitive, and humans often sniff to bring more odorant in contact with this area. The trigeminal nerves initiate protective reflexes, such as sneezing or interruption of irrhalation, with exposure to noxious odorants. 

Alternate ways to interfere with the orexin system may be via inhibition of dipeptidyl peptidases or proteolysis-resistant peptide analogs as shown for other peptides. This could prolong and boost orexinergic signaling. OX-A but not OX-B can enters the brain by simple diffusion via the blood-brain barrier. Abundance of orexins and their receptors in the olfactory bulb and throughout all parts of the central olfactory system may offer transnasal routes for drug application. 

The mechanisms by which the taste (and also the olfactory) system senses chemical compounds is assumed to occur by way of a chemoreceptory system that interacts effectively with a broad, structural variety of stimulant molecules, by means of a receptor epithelium consisting of the mosaic of adjacent, peripheral membranes of many receptor cells, exposed to a medium carrying stimulus molecules. A receptor cell is conveniently and, for our present purpose, sufficiently defined as a cell equipped to interact, according to some mechanism, with stimulus molecules, to convert the effect of this interaction into a signal, and to project this signal into the system. The taste receptor is thus a differentiated, epithelial cell synaptically contact-... 

The vertebrates produce, send and detect information which is conveyed by one or more molecular types. Chemical information of biological value (semiochemicals) which partly or wholly activates the accessory olfactory system (AOS) is transferred during intra- and inter-species communication. The compounds involved convey messages of social importance originating from the need to co-ordinate gamete release. It seems quite likely that gradual improvements by selection of semiochemical molecules and their receptors eventually enhanced the reproductive benefits both for the sender and for the receiver (Sorensen, 1996). The dual olfactory systems interpret chemical input to allow the discrimination of odour... 

The extent of compensatory changes, if any, within the main olfactory system could reveal something of the specificity or generality of... 

Prevention of access is the least intrusive method since it need not have any irreversible consequences for the afferent pathway. The common entrance to both olfactory systems in newts is easily closed-off by plugging the nostrils (Kikuyama et al., 1997). A potentially reversible method threaded plugs into the NP canal of cats via the nasal cavity (Verbeme, 1980). This procedure produced a slight effect on male chemoinvestigation of urine and or scent marks. The advantages of avoiding tissue disturbance then, have to be offset by the lack of any estimate of the effectiveness of the blockade, especially if reversible. Tissue cement injections into the N-Pd can be applied to the larger... 

Ultra-sound emissions typically occur when male rodents are exposed to female odours or altricial neonates to maternal sources (Whitney, 1974 Conely and Bell, 1978). Without the VNO, sexually inexperienced male mice do not utter emissions at ultra-high frequencies (UHF), whereas those with prior experience vocalise after VN-x, as discussed above (Chap. 5). Female mouse urine contains a unique UHF-eliciting component which is non-volatile but ephemeral (Sipos et al., 1995). The signal is degraded by oxidation and disappears within 15 to 18 hours of deposition. Direct contact with freshly voided urine must occur before males will vocalise (sexually experienced or inexperienced). At least one of the olfactory systems is needed for UHF to be elicited by fresh urine complete deafferentation abolishes the response (Sipos et al., 1993). Exposure to females permits UHF to be elicited by other than chemical cues (Labov and Wysocki, 1989). Nocturnal or cryptic species conceivably use ultrasound to advertise male presence whether this is to deter other males or assist with female location is unclear. 

Halasz N. (1990). The Vertebrate Olfactory System. Akad. Kiado, Budapest, p. 281. Hara T.J., ed. (1992). Fish Chemoreception. Chapman Hall, London, p. 373. 

Astic L., Le Pendu J., Mollicone R., Saucier D. and Oriol R. (1989). Cellular expression of H B antigens in the rat olfactory system during development. J Comp Neurol 289, 386-394. 

Beauchamp G.K., Martin I., Wysocki C.J. and Wellington J.L. (1983). The accessory olfactory system role in maintenance of chemoinvestigatory behavior. In Chemical Signals in Vertebrates 3 (Miiller-Schwarze D. and Silverstein R., eds.). Plenum, New York, pp. 73-86. 

Buck L. (1993). Receptor diversity and spatial patterning in the mammalian olfactory system. In The Molecular Basis of Smell and Taste Transduction (Chadwick D., et al., eds). John Wiley, London, Ciba Symposium 179, pp. 51-67. 

Clancy A.N., Schoenfeld T., Forbes W. and Macrides F. (1994). The spatial organization of the peripheral olfactory system of the hamster, II receptor surfaces and odorant passageways within the nasal cavity. Brain Res Bull 34, 211-241. 

Cohen-Tannoudji J., Lavenet C., Locatelli A., Teillet Y. and Signoret J.R (1989). Non involvement of the accessory olfactory system in the LH reponse of anestrous ewes to male odor. J Reprod Fertil 86, 135-144. 

Coppola D.M. and Millar L.C. (1994). Stimulus access to the accessory olfactory system in the prenatal and perinatal rat. Neuroscience 60, 463-468. 

Derivot J. (1984). Functional anatomy of the peripheral olfactory system of the African lungfish Pmtopterus annectens, Owen macroscopic, microscopic and morphometric aspects. Am J Anat 169, 177-192. 

Dudley C.A. and Moss R.L. (1994). Lesions of the accessory olfactory bulb decrease lordotic responsiveness and reduce mating-induced c-fos expression in the accessory olfactory system. Brain Res 642, 29-37. 

Eisthen H.L. (1997). Evolution of vertebrate olfactory systems. Brain Behav Evol 50, 222-233. 

Farbman A. (1991). Developmental neurobiology of the olfactory system. In Smell and Taste in Health and Disease (Getchell T.V., ed.). Raven Press, N.Y., pp. 19-33. 

Fleming A., Vaccarino F., Tambosso L. and Chee P. (1979). Vomeronasal and olfactory system modulation of maternal behaviour in the rat. Science 203, 372-374. 

Franceschini V., Lazzari M. and Ciani F. (1996). Identification of surface glycoconjugates in the olfactory system of turtle. Brain Res 725, 81-87. 

Halpem M., Shapiro L. and Jia C. (1998). Heterogeneity in the accessory olfactory system. Chem Senses 23, 477-481. 

Holtzman D.A. and Halpem M. (1990). Embryonic and neonatal development of the vomeronasal and olfactory systems in garter snakes. J Morphol 203, 123-140. 

Kapusta J., Marchlewska-Koj A., Olejnicza K. and Kruczek M. (1996). Removal of the olfactory system modifies male Bank Vole behavior in the presence of females. Behav Proc 37, 39-45. 

Kim K., Patel L Tobet S.A., King J.C., et al. (1999). Gonadotropin-releasing hormone immunoreactivity in the adult and fetal human olfactory system. Brain Res 826, 220-229. 

Lau Y. and Cherry J. (2000). Distribution of PDE4A and G(o)-alpha immunoreactivity in the accessory olfactory system of the mouse. Neurorep 11, 27-32. 

Levy F., Locatelli A., Piketty V., Tillet Y. and Poindron P. (1995). Involvement of the main but not the accessory olfactory system in maternal behavior of primiparous and multiparous ewes. Physiol Behav 57, 97-104. 

Lin D.M. and Ngai J. (1999). Development of the vertebrate main olfactory system. Curr Opin Neurobiol 9, 74-78. 

Mendoza A. (1993). Morphological studies on the rodent main and accessory olfactory systems the regio olfactoria and vomeronasal organ. Anat Anz 175, 425-446. 

Meredith M. (1991a). Sensory processing in the main and accessory olfactory systems comparisons and contrasts. J Ster Biochem Molec Biol 39(4b), 601-614. 

Meyer D.L., Jadhao A.G., Kiclite R., et al. (1997). Differential labelling of primary olfactory system sub-components by soybean agglutinin binding and NADOH-D histochemistry in the frog Pipa. Brain Res 762, 275-280. 

Mori K., von Campenhausen H. and Yoshihara Y. (2000). Zonal organization of the mammalian main and accessory olfactory systems. Phil Trans Roy Soc B 355, 1801-1812. 

Nef S., Allaman I., Fiumelli H., De Castro E., et al. (1996). Olfaction in birds differential embryonic expression of 9 putative OR genes in avian olfactory system. Mech Dev 55, 65-77. 

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