Project Title

Axonal regrowth of olfactory sensory neurons after chemical ablation with methimazole

Authors' Affiliations

Rudy T. Chapman, Katherine C. Burgess, Dr. Russ W. Brown, Dr. Diego J. Rodriguez-Gil, Department of Biomedical Science, Quillen College of Medicine, East Tennessee State University, Johnson City, TN

Location

WhiteTop Mountain Room 225

Start Date

4-5-2018 8:00 AM

End Date

4-5-2018 12:00 PM

Poster Number

107

Name of Project's Faculty Sponsor

Diego J. Rodriguez-Gil

Faculty Sponsor's Department

Biomedical Science

Type

Poster: Competitive

Classification of First Author

Graduate Student-Doctoral

Project's Category

Biomedical and Health Sciences

Abstract Text

The olfactory system is of great interest in research due to the olfactory epithelium’s regenerative capability and as a potential as a source of neural stem cells. The olfactory sensory neurons are constantly being replaced by the stem cells that lie at the base of the olfactory epithelium. These stem cells also remain intact after an injury to the epithelium and lead to the regeneration of the olfactory epithelium. We have developed a fate mapping technique to trace axonal regrowth from newly born olfactory sensory neurons using an inducible Cre-ERT2 model after chemical ablation by the drug methimazole. Our data shows that newly generated olfactory sensory neurons labeled 1 day after chemical ablation by injection of 4-HO-tamoxifen extend an axon that reaches the olfactory bulb and extend to the glomeruli in a timeline that is consistent with control mice that received 4-HO-tamoxifen but were injected with saline 1 day prior. In addition, we assessed the functional recovery of the olfactory epithelium by testing the ability of mice to find a hidden cookie after methimazole injection. Mice were tested at 3 and 14 days post methimazole. There was a severe impairment in the ability to find a hidden cookie at 3 days post methimazole. The mice tested at 14 days post methimazole showed an improvement in the ability to find the cookie but the latency to find the cookie was still significantly higher than controls. In conclusion, while we demonstrate that axons extend to the olfactory bulb and the glomeruli earlier than 14 days, our behavioral data suggest that there must be a critical number of axons that must reach each specific glomerulus to regain function of the olfactory system.

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Apr 5th, 8:00 AM Apr 5th, 12:00 PM

Axonal regrowth of olfactory sensory neurons after chemical ablation with methimazole

WhiteTop Mountain Room 225

The olfactory system is of great interest in research due to the olfactory epithelium’s regenerative capability and as a potential as a source of neural stem cells. The olfactory sensory neurons are constantly being replaced by the stem cells that lie at the base of the olfactory epithelium. These stem cells also remain intact after an injury to the epithelium and lead to the regeneration of the olfactory epithelium. We have developed a fate mapping technique to trace axonal regrowth from newly born olfactory sensory neurons using an inducible Cre-ERT2 model after chemical ablation by the drug methimazole. Our data shows that newly generated olfactory sensory neurons labeled 1 day after chemical ablation by injection of 4-HO-tamoxifen extend an axon that reaches the olfactory bulb and extend to the glomeruli in a timeline that is consistent with control mice that received 4-HO-tamoxifen but were injected with saline 1 day prior. In addition, we assessed the functional recovery of the olfactory epithelium by testing the ability of mice to find a hidden cookie after methimazole injection. Mice were tested at 3 and 14 days post methimazole. There was a severe impairment in the ability to find a hidden cookie at 3 days post methimazole. The mice tested at 14 days post methimazole showed an improvement in the ability to find the cookie but the latency to find the cookie was still significantly higher than controls. In conclusion, while we demonstrate that axons extend to the olfactory bulb and the glomeruli earlier than 14 days, our behavioral data suggest that there must be a critical number of axons that must reach each specific glomerulus to regain function of the olfactory system.