Search results for " Neurogenesis"

A critical period for experience-dependent remodeling of adult-born neuron connectivity.

2015

Neurogenesis in the dentate gyrus (DG) of the adult hippocampus is a process regulated by experience. To understand whether experience also modifies the connectivity of new neurons, we systematically investigated changes in their innervation following environmental enrichment (EE). We found that EE exposure between 2-6 weeks following neuron birth, rather than merely increasing the number of new neurons, profoundly affected their pattern of monosynaptic inputs. Both local innervation by interneurons and to even greater degree long-distance innervation by cortical neurons were markedly enhanced. Furthermore, following EE, new neurons received inputs from CA3 and CA1 inhibitory neurons that w…

Irradiation of the head reduces adult hippocampal neurogenesis and impairs spatial memory, but leaves overall health intact in rats.

2021

Treatment of brain cancer, glioma, can cause cognitive impairment as a side‐effect, possibly because it disrupts the integrity of the hippocampus, a structure vital for normal memory. Radiotherapy is commonly used to treat glioma, but the effects of irradiation on the brain are still poorly understood, and other biological effects have not been extensively studied. Here we exposed healthy adult male rats to small and moderate‐dose irradiation of the head. We found no effect of irradiation on systemic inflammation, weight gain or gut microbiota diversity, although it increased the abundance of Bacteroidaceae family, namely Bacteroides genus in the gut microbiota. Irradiation had no effect on…

Modulation of hippocampal neurogenesis by Nano-Pulsed Laser Therapy

Neurogenesis is a physiological process through which new neurons are generated and it occurs throughout life, subverting the old dogma stating to the inability of the adult brain to replace neurons. Specifically, neurogenesis take place thanks to the presence of neuronal stem cells (NSCs) located in the subventricular zone of the lateral ventricle and in the subgranular zone of the dentate gyrus of the hippocampus. Data present in the literature demonstrate that neurogenesis in the hippocampus decreases during aging and it is impaired in neurodegenerative diseases, such as Alzheimer’s disease, and after traumatic brain injury (TBI). Traumatic Brain Injury (TBI) is a chronic disease that oc…

The transcription factor Zfh1 is involved in the regulation of neuropeptide expression and growth of larval neuromuscular junctions in Drosophila mel…

2008

AbstractDifferent aspects of neural development are tightly regulated and the underlying mechanisms have to be transcriptionally well controlled. Here we present evidence that the transcription factor Zfh1, the Drosophila member of the conserved zfh1 gene family, is important for different steps of neuronal differentiation. First, we show that late larval expression of the neuropeptide FMRFamide is dependent on correct levels of Zfh1 and that this regulation is presumably direct via a conserved zfh1 homeodomain binding site in the FMRFamide enhancer. Using MARCM analysis we additionally examined the requirement for Zfh1 during embryonic and larval stages of motoneuron development. We could …

Retrograde monosynaptic tracing reveals the temporal evolution of inputs onto new neurons in the adult dentate gyrus and olfactory bulb

2013

Identifying the connectome of adult-generated neurons is essential for understanding how the preexisting circuitry is refined by neurogenesis. Changes in the pattern of connectivity are likely to control the differentiation process of newly generated neurons and exert an important influence on their unique capacity to contribute to information processing. Using a monosynaptic rabies virus-based tracing technique, we studied the evolving presynaptic connectivity of adult-generated neurons in the dentate gyrus (DG) of the hippocampus and olfactory bulb (OB) during the first weeks of their life. In both neurogenic zones, adult-generated neurons first receive local connections from multiple typ…

New scenarios for neuronal structural plasticity in non-neurogenic brain parenchyma: the case of cortical layer II immature neurons

2011

The mammalian central nervous system, due to its interaction with the environment, must be endowed with plasticity. Conversely, the nervous tissue must be substantially static to ensure connectional invariability. Structural plasticity can be viewed as a compromise between these requirements. In adult mammals, brain structural plasticity is strongly reduced with respect to other animal groups in the phylogenetic tree. It persists under different forms, which mainly consist of remodeling of neuronal shape and connectivity, and, to a lesser extent, the production of new neurons. Adult neurogenesis is mainly restricted within two neurogenic niches, yet some gliogenic and neurogenic processes a…

Poly-ADP-Ribose (PAR) as an epigenetic flag

2009

Epigenetics is the study of hereditable chromatin modifications, such as DNA methylation, histone modifications, and nucleosome-remodelling, which occur without alterations to the DNA sequence. The establishment of different epigenetic states in eukaryotes depends on regulatory mechanisms that induce structural changes in chromatin in response to environmental and cellular cues. Two classes of enzymes modulate chromatin accessibility: chromatin-covalent modifiers and ATP-dependent chromatin remodelling complexes. The first class of enzymes catalyzes covalent modifications of DNA as well as the amino- and carboxy-terminal tails of histones, while the second uses the energy of ATP hydrolysis …

Epigenetic regulation of stemness maintenance in the neurogenic niches

2015

In the adult mouse brain, the subventricular zone lining the lateral ventricles and the subgranular zone in the dentate gyrus of the hippocampus are two zones that contain neural stem cells (NSCs) with the capacity to give rise to neurons and glia during the entire life of the animal. Spatial and temporal regulation of gene expression in the NSCs population is established and maintained by the coordinated interaction between transcription factors and epigenetic regulators which control stem cell fate. Epigenetic mechanisms are heritable alterations in genome function that do not involve changes in DNA sequence itself but that modulate gene expression, acting as mediators between the environ…

Decreased Proliferation in the Neurogenic Niche, Disorganized Neuroblast Migration, and Increased Oligodendrogenesis in Adult Netrin-5-Deficient Mice.

2020

In the adult mouse brain, neurogenesis mainly occurs in the ventricular-subventricular zone (V-SVZ) and the subgranular zone of the hippocampal dentate gyrus. Neuroblasts generated in the V-SVZ migrate to the olfactory bulb via the rostral migratory stream in response to guidance molecules, such as netrin-1. We previously showed that the related netrin-5 (NTN5) is expressed in Mash1-positive transit-amplifying cells and doublecortin-positive neuroblasts in the granule cell layer of the olfactory bulb, the rostral migratory stream, and the subgranular zone of the adult mouse brain. However, the precise role of NTN5 in adult neurogenesis has not been investigated. In this study, we show that …

Regulation of the p19(Arf)/p53 pathway by histone acetylation underlies neural stem cell behavior in senescence-prone SAMP8 mice.

2015

Brain aging is associated with increased neurodegeneration and reduced neurogenesis. B1/neural stem cells (B1-NSCs) of the mouse subependymal zone (SEZ) support the ongoing production of olfactory bulb interneurons, but their neurogenic potential is progressively reduced as mice age. Although age-related changes in B1-NSCs may result from increased expression of tumor suppressor proteins, accumulation of DNA damage, metabolic alterations, and microenvironmental or systemic changes, the ultimate causes remain unclear. Senescence-accelerated-prone mice (SAMP8) relative to senescence-accelerated-resistant mice (SAMR1) exhibit signs of hastened senescence and can be used as a model for the stud…