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Histochem Cell Biol. 2012 Sep;138(3):477-88.
Evidence for a partial epithelial-mesenchymal
transition in postnatal stages of rat auditory organ
morphogenesis.
Johnen N, Francart ME, Thelen N, Cloes M, Thiry M.
Abstract
The epithelial-mesenchymal transition (EMT) plays a crucial role in the diferentiation of many
tissues and organs. So far, an EMT was not detected in the development of the auditory organ.
To determine whether an EMT may play a role in the morphogenesis of the auditory organ, we
studied the spatial localization of several EMT markers, the cell-cell adhesion molecules and
intermediate flament cytoskeletal proteins, in epithelium of the dorsal cochlea during deve-
lopment of the rat Corti organ from E18 (18th embryonic day) until P25 (25th postnatal day).
We examined by confocal microscopy immunolabelings on cryosections of whole cochleae
with antibodies anti-cytokeratins as well as with antibodies anti-vimentin, anti-E-cadherin and
anti-β-catenin. Our results showed a partial loss of E-cadherin and β-catenin and a temporary
appearance of vimentin in pillar cells and Deiters between P8 and P10. These observations
suggest that a partial EMT might be involved in the remodelling of the Corti organ during the
postnatal stages of development in rat.
Neuropsychopharmacology. 2012 Jun;37(7):1559-71.
Diferential efects of cocaine on dopamine neuron
fring in awake and anesthetized rats.
Koulchitsky S, De Backer B, Quertemont E, Charlier C, Seutin V.
Abstract
Cocaine (benzoylmethylecgonine), a natural alkaloid, is a powerful psychostimulant and a highly
addictive drug. Unfortunately, the relationships between its behavioral and electrophysiologi-
cal efects arenot clear.We investigatedtheefects of cocaineon thefringofmidbraindopami-
nergic (DA) neurons, both in anesthetized and awake rats, using pre-implanted multielectrode
arrays and a recently developed telemetric recording system. In anesthetized animals, cocaine
(10 mg/kg, intraperitoneally) produced a general decrease of the fring rate and bursting of
DA neurons, sometimes preceded by a transient increase in both parameters, as previous-
ly reported by others. In awake rats, however, injection of cocaine led to a very diferent
pattern of changes in fring. A decrease in fring rate and bursting was observed in only 14%
of DA neurons. Most of the other DA neurons underwent increases in fring rate and bursting:
these changes were correlated with locomotor activity in 52% of the neurons, but were
uncorrelated in 29% of them. Drug concentration measurements indicated that the observed
diferences between the two conditions did not have a pharmacokinetic origin. Taken toge-
ther, our results demonstrate that cocaine injection diferentially afects the electrical activity
of DA neurons in awake and anesthetized states. The observed increases in neuronal activity
may in part refect the cocaine-induced synaptic potentiation found ex vivo in these neurons.
Our observations also show that electrophysiological recordings in awake animals can uncover
drug efects, which are masked by general anesthesia.