A new study finds that the olfactory sensory neurons (OSNs) exhibit activity-dependent survival, a property that may be critical for an animal's ability to maximize and retain responsiveness to crucial odorants in its environment. The research, published in the March 25 issue of Neuron, finds that a molecular signaling pathway linked to neuronal survival in the central nervous system plays a significant role in odor-induced enhancement of olfactory cell survival.
It is well known that the olfactory epithelium can adapt in the very short term to odorant stimulation by receptor desensitization and habituation. However, the ability of odorants to stimulate long-lasting changes in OSNs has been suggested but not clearly elucidated. Dr. Daniel R. Storm and colleagues from The University of Washington in Seattle developed a novel method to monitor the survival of OSNs after stimulation with odorants and to examine the signaling pathways required for cell survival. OSNs were labeled using a sophisticated noninvasive adenovirus technique. Exposure to odorants enhanced the survival of subpopulations of unperturbed neurons and neurons that were exposed to a stimulus that normally causes cell death. Further investigation revealed that the ERK/MAP kinase/CREB pathway is directly involved in odorant-stimulated rescue of OSNs.
The researchers conclude that OSNs are capable of dynamic long-term adjustment to sensory information in the environment. This is significant for animals because the persistence of odorant-detecting cells would be dictated by odorants encountered in the environment, some of which might be critical for survival. These results are also important for humans. "The identification of a chemical pathway that protects olfactory sensory neurons from cell death has important medical implications since olfactory sensory neurons die during a number of conditions including sinusitis and head injury. In addition, we lose about 1% of our sense of smell per year as we age, and olfaction loss is associated with several neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The data in this paper suggests that drugs that activate the Erk/MAP kinase pathway may be used to protect olfactory sensory neurons from cell death associated with sinusitis, head injury, aging, and neurodegenerative diseases," explains Dr. Storm.
William C. Watt, Hitomi Sakano, Zong-Yi Lee, Jane E. Reusch, Kien Trinh and Daniel R. Storm: "Odorant Stimulation Enhances Survival of Olfactory Sensory Neurons via MAPK and CREB"
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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