Relationship between olfactory function and olfactory neuronal population in C57BL6 mice injected intraperitoneally with 3-methylindole.
OBJECTIVE
It is not known how many olfactory receptor neurons should be intact to maintain olfaction in mouse models treated with 3-methylindole. The aim of this study is to investigate the relationship between a simple olfactory test outcome and the olfactory neuronal population.


METHODS
Mouse model.


METHODS
Animal laboratory of the Seoul National University Bundang Hospital.


METHODS
Olfactory dysfunction was induced by intraperitoneal injection of 3-methylindole in 38 six-week-old female C57BL6 mice. Olfactory function was evaluated by a food-finding test following 72-hour starvation. The olfactory neuronal population was quantified by olfactory marker protein (OMP) expression.


RESULTS
The average time for finding food was 8.1 seconds in control mice. It was 13.4, 84.4, 90.1, and 111.4 seconds for mice injected with 100, 200, 300, and 400 μg/g of 3-methylindole, respectively. Harvesting the whole olfactory neuroepithelium, densitometric analysis showed significant decrease of OMP in the 300- and 400-μg/g groups as compared with controls (18.8% and 17.5% of relative density, respectively). In the olfactory bulb, there was a significant decrease of OMP in the 200-, 300-, and 400-μg/g groups (44.5%, 37.0%, and 9.0% of relative density, respectively). The food-finding time had a significant reverse correlation with the relative density of OMP both in the olfactory bulb and in the olfactory neuroepithelium.


CONCLUSIONS
Our study showed that olfactory impairment was correlated with olfactory neuronal population in mice treated with 3-methylindole. The food-finding test would be a useful tool that could be easily performed without special training in the 3-methylindole-treated C57BL6 anosmic mouse model.
Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. kimemail@snu.ac.kr
Jeong-Whun
JW
Kim
Sung-Lyong
SL
Hong
Chul Hee
CH
Lee
Eun-Hee
EH
Jeon
Ah-Reum
AR
Choi
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D007274:Injections, Intraperitoneal; D051379:Mice; D008810:Mice, Inbred C57BL; D009676:Noxae / Q000008:administration & dosage / Q000009:adverse effects*; D000857:Olfaction Disorders / Q000139:chemically induced*; D051842:Olfactory Marker Protein / Q000096:biosynthesis; D018034:Olfactory Receptor Neurons / Q000187:drug effects*; D012862:Skatole / Q000008:administration & dosage / Q000009:adverse effects*; D012903:Smell / Q000187:drug effects*
D009676:Noxae; D051842:Olfactory Marker Protein; C497598:Omp protein, mouse; D012862:Skatole