ABSTRACT
This study was carried out to investigate alterations of neurofilament 200 kDa (NF-200) and its polyphosphorylation form (RT97) immunoreactivity and protein content in the main olfactory bulb (MOB) after 5 min of transient forebrain ischemia in gerbils. In the sham-operated group, weak NF-200 immunoreactivity was detectable in a few somata of mitral cells, which projected weak NF-200-immunoreactive processes to the external plexiform layer (EPL). At 1-5 days after ischemia, strong NF-200 and RT97 immunoreactivity was shown by the mitral cell processes; however, somata of mitral cells did not show NF-200 immunoreactivity. At this time point, strong NF-200-immunoreactive mitral cell processes ran to the EPL and glomerular layer (GL). Thereafter, NF-200 and RT97 immunoreactivity was decreased up to 30 days after ischemia. In the 15 days post-ischemic group, the distribution pattern of NF-200 and RT97 immunoreactivity was slightly lower than that in the 1-5 days post-ischemic groups. In the 30 days post-ischemic group, moderate NF-200 and RT97 immunoreactivity was found in the mitral cells processes, but the immunoreactivity in the EPL and GL nearly disappeared. A Western blot study showed a pattern of NF-200 and RT97 expression at all post-ischemic time points similar to that of immunohistochemistry after ischemia. This result indicates that NF-200 and RT97 accumulates in injured mitral cell processes a few days after transient ischemia, which suggests that the axonal transport in the MOB may be disturbed during this period after transient ischemia.
Subject(s)
Brain Ischemia/metabolism , Ischemic Attack, Transient/metabolism , Neurofilament Proteins/metabolism , Olfactory Bulb/metabolism , Animals , Axonal Transport/physiology , Axons/immunology , Axons/pathology , Blotting, Western , Brain Ischemia/physiopathology , Cytoskeleton/metabolism , Cytoskeleton/pathology , Disease Models, Animal , Gerbillinae , Immunohistochemistry , Ischemic Attack, Transient/physiopathology , Male , Neurons/immunology , Neurons/pathology , Neuropil/immunology , Neuropil/pathology , Olfactory Bulb/pathology , Olfactory Bulb/physiopathology , Olfactory Pathways/immunology , Olfactory Pathways/pathology , Olfactory Pathways/physiopathology , Phosphorylation , Proteins/analysis , Proteins/metabolism , Time FactorsABSTRACT
This study was carried out to investigate the transient ischemia-induced changes of neurofilament 200 kDa (NF-200) immunoreactivity and protein content in the gerbil lateral olfactory tract (LOT) after 5 min of transient forebrain ischemia. Weak NF-200 immunoreactivity was detectable in the LOT in the sham-operated group. In this group, a few somata of mitral cells showed weak NF-200 immunoreactivity. One day after transient ischemia, NF-200 immunoreactivity in the LOT was increased significantly. NF-200 immunoreactivity in the LOT by 15 days after ischemia was similar to that in the 1 day post-ischemic group. In this time period, strong NF-200 immunoreactivity was expressed in the mitral cell processes, but the immunoreactivity in the mitral cell somata was significantly decreased. Thereafter, NF-200 immunoreactivity in the LOT was decreased significantly by 30 days after ischemic insult. At this time after ischemia, NF-200 immunoreactivity in the mitral cell dendrites was significantly decreased. The result of Western blot study showed that the pattern of NF-200 expression was similar to that of immunohistochemistry after ischemia-reperfusion. Our result suggests that changes of NF-200 protein in the gerbil LOT may be related to response to ischemic damage and that the axonal transport followed transient ischemia may be disturbed.
