ODORS INCREASE FOS IN OLFACTORY-BULB NEURONS INCLUDING DOPAMINERGIC CELLS

NEURONAL activity may lead to long lasting changes in cell phenotype t hrough induction of genes such as c-fos which encode transcriptional r egulatory factors. Odor-activated olfactory bulb cells exhibit increas es in c-fos mRNA expression. The present study examined whether odor s timulation of awake rats also leads to increases in Fos protein in the se cells. The phenotype of Fos-immunoreactive cells was partially char acterized using double-immunoperoxidase staining. Odor exposure increa sed Fos-immunoreactivity (IR) in specific sets of olfactory bulb neuro ns. Fos-IR was not co-localized with IR for glial fibrillary acidic pr otein, but was co-localized with tyrosine hydroxylase (TH)-IR in a sub population of dopaminergic neurons, suggesting that bulbar TH expressi on may be regulated in part by a Fos mechanism.