title: [Expression of odorant receptor genes on the olfactory epithelium following olfactory nerve disconnection].
abstract: OBJECTIVE
  To constitute the animal model of unilateral olfactory nerve transection and observe the expression level and distribution of odorant receptors.
  
  
  METHODS
  Thirty-two rats were divided into two groups: the olfactory nerve transection group (20) and the control group (12). The former group received the operation to transect the left olfactory nerve following the left olfactory bulb was exposed under microscope and the latter group did not give any disposal. At every stage of five days, two weeks, four weeks and six weeks after the operation, five rats from the nerve transection group and three from the control group were anaesthetized simultaneously, and olfactory epithelium were taken out after transcardial perfusion, then paraffin imbedding. Coronal sections were sliced for HE staining to observe the thickness changes of the olfactory epithelium, and for in situ hybridization (ISHs) to investigate the expression of olfactory receptor genes (Olr287, Olr226, Olr1493 and Olr1654) in the epithelium, also to evaluate the changes of the expression level and location of the selected receptors during the regeneration of olfactory epithelium.
  
  
  RESULTS
  HE staining showed that 5 days after the operation cell quantity and thickness of the olfactory epithelium decreased obviously, which increased gradually 2 or 4 weeks after operation. After 6 weeks' recovery, the thickness of the epithelium could reach the control level. The pattern of cell staining by ISH showed a specific spatial distribution along the anteroposterior (AP) and dorsoventral (DV) axis. Evidence suggested that odorant receptors were distributed in continuous and multiple overlapping bands in the normal or nerve transected-recovered epithelium rather than in the conventionally accepted three or four zones. The data also demonstrated that the distribution of sensory neuron types, as identified and defined by odorant receptor expression, was restored to normal or nearly so by 6 weeks after operation. Likewise, the numbers of probe-labeled neurons in the nerve transected-recovered had an obvious decrease 5 days after olfactory nerve transection. Reactive cells (x(-) +/- s) of Olr1493 in the operated side was (53.9 +/- 19.9), compared with (419.0 +/- 21.2) in the unoperated side, there was statistic significance between them (t = 63.960, P < 0.01). Reactive cells increased gradually according to the regeneration of the epithelium, and were nearly equivalent to the normal side 6 weeks later without significant differentiation (t = 2.600, P > 0.05), according to the absolute positive cells in the operated and unoperated side of (417.8 +/- 32.4) and (445.3 +/- 10.0) respectively.
  
  
  CONCLUSIONS
  The regeneration of the sensory neurons and receptors, both the number and the distribution, can recover to normal after olfactory nerve transection.
authors: Department of Otorhinolaryngology Head and Neck Surgery, Beijing Tongren Hospital Affiliated of Capital Medical University, Beijing 100730, China.
authors: Yue-hong
authors: YH
authors: Liu
authors: Yong-xiang
authors: YX
authors: Wei
authors: Ling
authors: L
authors: Yang
authors: Xu-tao
authors: XT
authors: Miao
authors: Ya-yan
authors: YY
authors: Lu
authors: Er-zhong
authors: EZ
authors: Fan
authors: Xiao-chao
authors: XC
authors: Liu
authors: Jing-feng
authors: JF
authors: Zhang
mesh_terms: D000818:Animals; D008297:Male; D009831:Olfactory Mucosa / Q000378:metabolism*; D009832:Olfactory Nerve / Q000378:metabolism* / Q000601:surgery; D061219:Olfactory Nerve Injuries; D018034:Olfactory Receptor Neurons / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*
chemical_list: D018035:Receptors, Odorant