Volume 17, Number 9,
Issue of May 1, 1997
pp. 3120-3127
Copyright ©1997 Society for Neuroscience
In Vitro Generation of Adult Rat Olfactory Sensory
Neurons and Regulation of Maturation by Coculture with CNS
Tissues
Received July 11, 1996; revised Jan. 22, 1997; accepted Jan. 31, 1997.
Raymond J. Grill and
Sarah K. Pixley
Department of Cell Biology, Neurobiology and Anatomy, University of
Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521
Olfactory sensory neurons (OSNs) are continually generated
throughout life. Although previous studies have examined neurogenesis in olfactory cell cultures derived from embryonic or newborn rodents, we demonstrate neurogenesis in cell cultures derived from adult rat
tissues. Dissociated cells taken from adult rat nasal mucosal tissues
(ANM cells) were plated onto a feeder layer of newborn rat cortical
glia (astrocytes) in serum-free conditions. Immature OSNs (stained for
neuron-specific tubulin, NST) increased in number between 1 and 5 d in vitro (DIV) and in mass thereafter. Mature OSN
(stained for olfactory marker protein, OMP) numbers decreased between 1 and 5 DIV, then increased over 5 DIV values by 12 and 15 DIV. Pulse
labeling with [3H]thymidine confirmed in
vitro neurogenesis. To determine whether the target cells for
OSNs, olfactory bulb (OB) neurons, provide trophic support, dissociated
newborn rat OB cells were cocultured with ANM cells on glia. This
resulted in greater numbers of OMP-positive (OMP+) neurons after 9 DIV
than ANM-alone cultures. This neurotrophic effect was not OB specific.
Addition of newborn rat cerebellar and embryonic rat ventral
mesencephalic cells to ANM cells also increased OMP+ neurons, whereas
addition of newborn rat cortical cells or controls (purified glia or
fibroblasts) did not. Changes in numbers of dopaminergic neurons
(stained for tyrosine hydroxylase), present in OB and VM cultures, did
not correlate with OMP+ neuronal increases. Thus, cultures of adult rat
OSNs demonstrate neurogenesis, and trophic/maturation support is
variably provided by CNS neurons (and not glia).
Key words:
olfactory mucosa;
neurogenesis;
neuronal maturation;
rat;
nerve growth factors;
cell culture;
cocultures