Recent publications have demonstrated an important role for olfactory innervation in maintenance of the dopaminergic neuron of the rat olfactory bulb. These studies employed the model of unilateral naris occlusion to investigate the effects of lack of odorant stimulation on dopamine expression in the olfactory bulb of the 4 weeks old rat. Immunoreactivity of tyrosine hydrorylase (TH), the first and rate-limiting enzyme in dopamine biosynthesis, used as a marker of the dopamine system, exhibited a gradual decrease by the time(21, 28, and 49 days) of unilateral naris occlusion. The losses of the tyrosine hydroaylase immunoreactivity (TH-ir) were mainly observed in the periglomerular cell of the ipsilateral olfactory bulb of the naris occlusion side. However, there is no TH-it decrease in juxtaglomerular region of the ipsilateral olfactory bulb in saris occlusion side. Not observed the decrease of the olfactory bulb size accompanying of the decrease TH-ir.
These data indicate that saris occlusion of the 4 weeks old rat, and the resulting lack of odorant stimulation, produces a transneuronal alteration in dopamine expression.
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