0000000000002509
AUTHOR
Maria Belles
PSA-NCAM is expressed in immature, but not recently generated, neurons in the adult cat cerebral cortex layer II
Neuronal production persists during adulthood in the dentate gyrus and the olfactory bulb, where substantial numbers of immature neurons can be found. These cells can also be found in the paleocortex layer II of adult rodents, but in this case most of them have been generated during embryogenesis. Recent reports have described the presence of similar cells, with a wider distribution, in the cerebral cortex of adult cats and primates and have suggested that they may develop into interneurons. The objective of this study is to verify this hypothesis and to explore the origin of these immature neurons in adult cats. We have analyzed their distribution using immunohistochemical analysis of the …
Pregnancy Changes the Response of the Vomeronasal and Olfactory Systems to Pups in Mice
Motherhood entails changes in behavior with increased motivation for pups, induced in part by pregnancy hormones acting upon the brain. This work explores whether this alters sensory processing of pup-derived chemosignals. To do so, we analyse the expression of immediate early genes (IEGs) in the vomeronasal organ (VNO; Egr1) and centers of the olfactory and vomeronasal brain pathways (cFos) in virgin and late-pregnant females exposed to pups, as compared to buttons (socially neutral control). In pup-exposed females, we quantified diverse behaviors including pup retrieval, sniffing, pup-directed attack, nest building and time in nest or on nest, as well as time off nest. Pups induce Egr1 ex…
Olfactory bulbectomy, but not odor conditioned aversion, induces the differentiation of immature neurons in the adult rat piriform cortex.
International audience; The piriform cortex layer II of young-adult rats presents a population of prenatally generated cells, which express immature neuronal markers, such as the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) or doublecortin (DCX), and display structural characteristics of immature neurons. The number of PSA-NCAM/DCX expressing cells in this region decreases markedly as age progresses, suggesting that these cells differentiate or die. Since the piriform cortex receives a major input from the olfactory bulb and participates in olfactory information processing, it is possible that the immature neurons in layer II are affected by manipulations of the olfac…
A "double hit" murine model for schizophrenia shows alterations in the structure and neurochemistry of the medial prefrontal cortex and the hippocampus.
Both alterations in neurodevelopment and aversive experiences during childhood and adolescence seem important risk factors for schizophrenia. Animal models reproducing these alterations mimic some of the symptoms, constituting a valid approach to study the etiopathology of this disorder. Among these models, the perinatal injection of N-methyl-d-aspartate receptor antagonists and the postweaning social isolation rearing are among the most widely used. Our aim is to combine them in a "double hit" model, which should produce a wider spectrum of alterations. Lister Hooded rats have been subjected to a single injection of MK-801 at postnatal day 7 and socially isolated from postweaning to adulth…
Characterization and isolation of immature neurons of the adult mouse piriform cortex
Physiological studies indicate that the piriform or primary olfactory cortex of adult mammals exhibits a high degree of synaptic plasticity. Interestingly, a subpopulation of cells in the layer II of the adult piriform cortex expresses neurodevelopmental markers, such as the polysialylated form of neural cell adhesion molecule (PSA-NCAM) or doublecortin (DCX). This study analyzes the nature, origin, and potential function of these poorly understood cells in mice. As previously described in rats, most of the PSA-NCAM expressing cells in layer II could be morphologically classified as tangled cells and only a small proportion of larger cells could be considered semilunar-pyramidal transitiona…
Early Social Isolation Stress and Perinatal NMDA Receptor Antagonist Treatment Induce Changes in the Structure and Neurochemistry of Inhibitory Neurons of the Adult Amygdala and Prefrontal Cortex
AbstractThe exposure to aversive experiences during early life influences brain development and leads to altered behavior. Moreover, the combination of these experiences with subtle alterations in neurodevelopment may contribute to the emergence of psychiatric disorders, such as schizophrenia. Recent hypotheses suggest that imbalances between excitatory and inhibitory (E/I) neurotransmission, especially in the prefrontal cortex and the amygdala, may underlie their etiopathology. In order to understand better the neurobiological bases of these alterations, we studied the impact of altered neurodevelopment and chronic early-life stress on these two brain regions. Transgenic mice displaying fl…
Maternal Motivation: Exploring the Roles of Prolactin and Pup Stimuli
Motherhood entails increased motivation for pups, which become strong reinforcers and guide maternal behaviours. This depends on steroids and lactogens acting on the brain of females during pregnancy and postpartum. Since virgin female mice exposed to pups are nearly spontaneously maternal, the specific roles of endocrine and pup-derived signals in the induction of maternal motivation remain unclear. This work investigates maternal motivation in dams and virgin female mice, using a novel variant of the pup retrieval paradigm, the motivated pup retrieval test. We also analyse the role of prolactin (PRL) and of stimuli derived from a litter of pups and its mother, in the acquisition of matern…
Cellular Plasticity in the Adult Murine Piriform Cortex: Continuous Maturation of Dormant Precursors Into Excitatory Neurons
Neurogenesis in the healthy adult murine brain is based on proliferation and integration of stem/progenitor cells and is thought to be restricted to 2 neurogenic niches: the subventricular zone and the dentate gyrus. Intriguingly, cells expressing the immature neuronal marker doublecortin (DCX) and the polysialylated-neural cell adhesion molecule reside in layer II of the piriform cortex. Apparently, these cells progressively disappear along the course of ageing, while their fate and function remain unclear. Using DCX-CreERT2/Flox-EGFP transgenic mice, we demonstrate that these immature neurons located in the murine piriform cortex do not vanish in the course of aging, but progressively res…
The activation of NMDA receptors alters the structural dynamics of the spines of hippocampal interneurons
N-Methyl-d-Aspartate receptors (NMDARs) are present in both pyramidal neurons and interneurons of the hippocampus. These receptors play a key role in the structural plasticity of excitatory neurons, but to date little is known about their influence on the remodeling of interneurons. Among hippocampal interneurons, the somatostatin expressing cells in the CA1 stratum oriens are of special interest because of their functional importance and structural characteristics: they display dendritic spines, which change their density in response to different stimuli. In order to understand the role of NMDAR activation on the structural dynamics of the spines of somatostatin expressing interneurons in …
PSA Depletion Induces the Differentiation of Immature Neurons in the Piriform Cortex of Adult Mice
Immature neurons are maintained in cortical regions of the adult mammalian brain. In rodents, many of these immature neurons can be identified in the piriform cortex based on their high expression of early neuronal markers, such as doublecortin (DCX) and the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). This molecule plays critical roles in different neurodevelopmental events. Taking advantage of a DCX-CreERT2/Flox-EGFP reporter mice, we investigated the impact of targeted PSA enzymatic depletion in the piriform cortex on the fate of immature neurons. We report here that the removal of PSA accelerated the final development of immature neurons. This was revealed by a h…