Characterization by Gene Expression Analysis of Two Groups of Dopaminergic Cells Isolated from the Mouse Olfactory Bulb

Abstract

The olfactory bulb (OB) is one of two regions of the mammalian brain which undergo continuous neuronal replacement during adulthood. A significant fraction of the cells added in adulthood to the bulbar circuitry is constituted by dopaminergic (DA) neurons. We took advantage of a peculiar property of dopaminergic neurons in transgenic mice expressing eGFP under the tyrosine hydroxylase (TH) promoter: while DA neurons located in the glomerular layer (GL) display full electrophysiological maturation, eGFP+ cells in the mitral layer (ML) show characteristics of immature cells. In addition, they also display a lower fluorescence intensity, possibly reflecting different degrees of maturation. To investigate whether this difference in maturation might be confirmed at the gene expression level, we used a fluorescence-activated cell sorting technique on enzymatically dissociated cells of the OB. The cells were divided into two groups based on their level of fluorescence, possibly corresponding to immature ML cells and fully mature DA neurons from the GL. Semiquantitative real-time PCR was performed to detect the level of expression of genes linked to the degree of maturation of DA neurons. We showed that indeed the cells expressing low eGFP fluorescence are immature neurons. Our method can be further used to explore the differences between these two groups of DA neurons.

Retinal Alterations Predict Early Prodromal Signs of Neurodegenerative Disease

“…In contrast with the retina, DA neuron numbers in the olfactory bulb of people with PD and in Parkinsonian rodent models are dramatically higher [192][193][194]. A possible explanation for this paradox may be attributed to the process of adult neurogenesis that occurs in the olfactory bulb, which would lead to a compensatory mechanism, although the reason for this increase in people with PD remains unclear [195][196][197][198].…”

State of the Art of Pharmacological Activators of p53 in Ocular Malignancies

“…It is noteworthy that p53 exhibits widespread expression in various regions of the brain and the entire eye of adult mice. The expression is particularly high in the retina and optic nerve, while also accounting for a substantial portion, up to 70%, p53 is expressed at high levels during normal embryogenesis and development, regulating cell cycle and apoptosis [90], in the central nervous system (CNS) as well as other anatomical compartments such as olfactory bulb and eye [91][92][93][94][95][96]. Studies in an animal model showed a marked role of p53 during early embryonic ocular development, highlighting ocular abnormalities of hyaloid vasculature, vitreal opacities, retinal folding, and nerve fiber hypoplasia in mice defective for p53, according to their genetic background [97].…”