BULBAR MORPHOLOGY AND EXPRESSION OF BULBAR DOPAMINE AND PARVALBUMIN IN EXPERIMENTALLY-INDUCED ANOSMIC RATS

Morphological study was carried out in rats with olfactory dysfunction induced by deafferentation of serotonergic fibers in the olfactory bu lb. With a computer capable of area measurements, olfactory bulbs of t he anosmic rats were found to be decreased in size to 61% of control b ulbs, and all bulbar layers were involved in the bulbar shrinkage. Giv en areas of each bulbar layer in control bulbs to be 100%, percentages of each bulbar layer in the anosmic rats were 23% in the olfactory ne rve layer, 54% in the glomerular layer, 63% in the external plexiform layer, 83% in the internal plexiform layer and 81% in the granule cell layer. Dopamine-and parvalbumin-containing neurons were examined immu nohistochemically in the experimentally-induced anosmic rats. As a res ult, immunoreactive neurons for these two chemical substances were sig nificantly decreased in number (dopamine, 33% of control value; parval bumin, 46% of control value). The present study, using an animal model of anosmia, provided quantitative data on the bulbar atrophy and show ed effects of anosmia on expression of dopamine and parvalbumin in the bulb.