Altered epithelial density and expansion of bulbar projections of a discrete HSP70 immunoreactive subpopulation of rat olfactory receptor neurons in reconstituting olfactory epithelium following exposure to methyl bromide

J Comp Neurol. 2004 Feb 16;469(4):475-93. doi: 10.1002/cne.11020.


A previously described subpopulation of rat olfactory receptor neurons, the 2A4(+)ORNs, is 1) distinguished by intense constitutive cytoplasmic immunoreactivity to antibodies to the 70-kD heat shock protein (HSP70); 2) occurs sparsely but consistently through ventral and lateral olfactory epithelium (OE); and 3) projects to just two to three consistently located glomeruli in each olfactory bulb (OB) (Carr et al. [1994] J Comp Neurol 348:150-160). Immunoreactivity appears not to be stress-related. To examine the persistence of these features following destruction and reconstitution of the OE, rats were subjected to methyl bromide-induced OE lesion (Schwob et al. [1995] J Comp Neurol 59:15-37; Schwob et al. [1999] J Comp Neurol 412:439-457] and their OE and OBs examined with antibodies to HSP70 6-10.5 weeks postlesion. Lesioned OE showed significantly increased 2A4(+)ORN densities but no alteration of 2A4(+)ORN zonal distribution. The OBs of lesioned animals showed marked expansions of 2A4(+)ORN bulbar projections, with 2-15-fold increases in numbers of glomeruli showing 2A4(+)axons, and projection expansions were greater in animals maintained on chronic food restriction prior to lesioning. Examination of archival 5-month post-MeBr lesion material indicates that altered projection patterns are maintained.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / metabolism
  • Cell Count
  • Food Deprivation
  • Functional Laterality
  • HSP70 Heat-Shock Proteins / metabolism*
  • Humans
  • Hydrocarbons, Brominated / toxicity*
  • Immunohistochemistry / methods
  • Male
  • Mice
  • Nerve Regeneration / drug effects
  • Nerve Regeneration / physiology
  • Olfactory Bulb / cytology
  • Olfactory Bulb / metabolism
  • Olfactory Mucosa / cytology
  • Olfactory Mucosa / drug effects*
  • Olfactory Pathways / metabolism*
  • Olfactory Receptor Neurons / drug effects*
  • Olfactory Receptor Neurons / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Time Factors


  • Antibodies, Monoclonal
  • HSP70 Heat-Shock Proteins
  • Hydrocarbons, Brominated
  • methyl bromide