Nerve, olfactory

There are certain weU-estabUshed facts about olfaction (6). AU normal people can smell. People suffering from brain lesions, injured olfactory nerve, or obstmcted nasal passages may be anosmic. Cases of preferential anosmia, ie, abUity to sense certain smells and not others, are not weU estabUshed. Such cases occur, but Utde is known of them. 

Some materials with low odour duesholds may paralyse die olfactory nerves and cause the sense of smell to be lost within minutes (e.g. hydrogen sulphide). 

Detectable odour Conjunctivitis Olfactory nerve paralysis... 

C02-0035. When we smell the odor of a rose, our olfactory nerves are sensing molecules of the scent. Explain how smelling a rose demonstrates that molecules are always moving. 

Burton P.R. (1990). Vomeronasal and olfactory nerves of adult and larval bullfrogs II. Axon terminations and synaptic contracts in the accessory olfactory bulb. J Comp Neurol 292, 624-637. 

Miwa T., Moriizumi T., Sakashita H. and Kimura Y. (1993). Transection of the olfactory nerves induces expression of nerve growth factor receptor in mouse olfactory epithelium. Neurosci Lett 155, 96-98. 

Norgren R.J., Gao C., Ji Y. and Fritzsch B. (1995). Tangential migration of luteinizing hormone-releasing hormone (LHRH) neurons in the medial telencephalon in association with transient axons extending from the olfactory nerve. Neurosci Lett 202, 9-12. 

Ennis M., Zhou F., Ciombor K. et al. (2001). Dopamine D2 receptor-mediated presynaptic inhibition of olfactory nerve terminals. J. Neurophysiol. 86,... 

Zuri, I. and Halpem, M. (2003) Differential effects of lesions of the vomeronasal and olfactory nerves on garter snake (Thamnophis sirtalis) response to airborne chemical stimuli. Behav. Neurosci. 117, 169-183. 

The cyclase produces cAMP which results in opening of a Na" ion channel in the membrane of the sensory cell. If a sufficient number of Na " ions enter, this depolarises the membrane and initiates an action potential along the axon to the olfactory nerve. Further effects depend upon interaction between the nerves and synapses within the olfactory centre in the brain. This can result in physiological effects in other parts of the body which define the function of the pheromone. The effects of pheromones on the sexual responses of men and women are discussed in Chapter 19 (see Figure 19.17). 

Many petrels and shearwaters approach their nest burrow, often located under forest cover, at night. When Leach s petrel Occanodroma leucorrhoa) return to their nest, they first hover over the spruce-fir canopy near their burrow. Then they plummet to the ground several meters downwind from their nest site and walk upwind to their burrows (Fig. 4.6). In still air, they landed closer to the burrow and followed a more roundabout route than in wind. With external nares plugged or olfactory nerves transected, displaced birds did not return to their burrows for 1 week. In a laboratory two-choice apparatus, breeding petrels... 

During the last 30 years, several laboratories have examined homing pigeons for their ability to use odors for orientation. Early experiments suggested that olfaction is important in orientation homing pigeons with their olfactory nerves cut were generally found to be unable to home from short... 

Social odors have rarely been reported in birds. The respiration rate of wedge-tailed shearwaters Puffinus pacificus) increases in response to the odor of an unfamiliar conspecific (Shallenberger, 1975). Domestic ducks altered social and sexual behavior after bilateral section of the olfactory nerve, or after treatment with amyl acetate or ethyl acrylate (Balthazart and Schoffeniels, 1979). Some bird species are known for their strong characteristic odors. For instance. 

Adults continue to associate new odors with pleasant and unpleasant situations in social and sex life, work and recreation, and concerning food and drink. The human patterns of odor recognition and preferences do not merely involve the olfactory nerve and its central projections. Learned associations are formed and stored in memoiy. To retrieve odor information, we need affective and cognitive components, as well as verbal descriptors. Without the latter, an odor appears familiar but cannot be labeled, the tip-of-the-nose-phenomenon (Lawless and Engen, 1977). 

Not surprisingly, much research in sharks, skates and rays has focused on the responses of sharks to human body odors. Human blood attracts sharks, while sweat does not, and urine was even slightly repellent (Tester, 1963). Practitioners use whale meat and mixtures of fish meal and fish oils as shark attrac-tants. In both carnivorous and herbivorous bony fish (Osteichthyes) smell deals with prey odors, social odors, and chemical stimuli in homing, and it is mediated by the first cranial nerve, the olfactory nerve. By contrast, taste serves in detection and selection of food and avoidance of toxic food, and it employs the facial, glossopharyngeal, vagal, and hypoglossal nerves. 

Benvenuti, S., Fiaschi, V., Fiore, L., and Papi, F. (1973). Homing performance of inexperienced and directionally trained pigeons subjected to olfactory nerve section. Journal of Comparative Physiology 83,81-92. 

Other consequences of cadmium exposure are anemia, eosinophilia, yellow discoloration of the teeth, rhinitis, occasional ulceration of the nasal septum, damage to the olfactory nerve, and anosmia. ... 

Receptor-mediated endocytosis may be possible because receptors have a high affinity for BDNF (Deckner et al. 1993). A linear relation between intranasal administration of -labeled NGF and brain concentrations of the compound suggest that this transportation is not mediated by receptors and that this releasing method of agents to the brain via olfactory nerves may be effective for many therapies (Frey et al. 1995). BDNF and the insulin-type growth factor (IGF-1) are currently used in clinical studies (Appel 1997). 

Various poisonous chemical components in geothermal steam escape into the atmosphere from electric power plants via ejector exhausts, cooling towers, silencers, and drains and traps. These compounds include H2S, B, Hg, As, and Rn. Other compounds of environmental concern in geothermal steam, although not poisonous, include C02 and CH4. Apparently, not much attention has been paid to airborne poisons in geothermal steam other than H2S. This noxious gas has an unpleasant smell when present in low and harmless concentrations. When more strongly concentrated, H2S can paralyse the olfactory nerves and thus becomes odourless, and eventually lethal. 

The visualization of the optic and olfactory nerves was possible due to the ability of manganese(II) to be taken up by the calcium(II) channels in neurons... 

IGF-binding proteins. Protein binding of IGF-1 serves to increase its half-life. Thorne et al. [109] demonstrated that in rats, nasally administered IGF-1 was rapidly transported into the brain. IGF-1 uptake into the brain appeared to follow two routes, through olfactory nerve tracts and through trigeminal associated extracellular pathways. The net effect of nasal IGF-1 administration in rats was to rapidly elicit biological effects at several sites in the brain. 

As i.n. administration delivers the drug to the brain directly via the olfactory nerve and olfactory epithelium, this method may be favored for administration of drugs that are rapidly metabolized when given systemically or have difficulty crossing the blood-brain barrier (27). For example, in rats, i.n. dopamine has been shown to decrease grooming activity and increase locomotor activity in the open field at one tenth of the dose needed to observe these effects when the drug is administered i.p. (27) also see data on its antidepressant effects (28). 

The glomerular layer of the olfactory bulb contains a substantial population of dopaminergic neurons. Dopamine acting at D2-like heteroreceptors inhibits glutamate release from terminals of the olfactory sensory neurons and hence may modulate the olfactory nerve synapse (Table 1). 

Berkowicz DA, Trombley PQ (2000) Dopaminergic modulation at the olfactory nerve synapse. Brain Res 855 90-9... 

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