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.
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.
McMillan Carr
Virginia
V
Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA. v-carr@northwestern.edu
Ring
George
G
Youngentob
Steven L
SL
Schwob
James E
JE
Farbman
Albert I
AI
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002452:Cell Count; D005508:Food Deprivation; D007839:Functional Laterality; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D006842:Hydrocarbons, Brominated / Q000633:toxicity*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology; D009830:Olfactory Bulb / Q000166:cytology / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology / Q000187:drug effects*; D009833:Olfactory Pathways / Q000378:metabolism*; D018034:Olfactory Receptor Neurons / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D000911:Antibodies, Monoclonal; D018840:HSP70 Heat-Shock Proteins; D006842:Hydrocarbons, Brominated; C005218:methyl bromide