scholarly journals Long-lasting effects of transient, perinatal fluoxetine exposure on cell proliferation in the dentate gyrus of mice

2019 ◽  
Author(s):  
Simon C. Spanswick ◽  
Michael J. Chrusch ◽  
Veronika Kiryanova ◽  
Richard H. Dyck
Keyword(s):  
Hippocampal Neurons ◽  
Developmental Period ◽  
Hippocampal Neurogenesis ◽  
Mammalian Brain ◽  
Long Term Effects ◽  
Neuronal Proliferation ◽  
Adult Born Neurons ◽  
Adult Mammalian Brain ◽  
Homeostatic Mechanisms

AbstractIn the adult mammalian brain, up-regulation of serotonin via the selective serotonin reuptake inhibitor fluoxetine increases hippocampal neurogenesis. However, research assessing the long-term effects of modulating serotonin during the developmental period on hippocampal neurogenesis, is sparse. Here we evaluated hippocampal neurogenesis early (postnatal day 12), and later in life (postnatal day 60), in the offspring of mouse dams that were administered fluoxetine in their drinking water from embryonic day 15 (E15) through postnatal day 12 (P12). Fluoxetine-exposed mice had significantly higher levels of neuronal proliferation at P12, and P60, despite cessation of fluoxetine on P12. These effects were limited to proliferation, as survival of postnatal-born hippocampal neurons was unaltered. Mice exposed to fluoxetine also showed significantly higher levels of cell death, suggesting that homeostatic mechanisms present within the hippocampus may limit integration of adult-born neurons into the existing neuronal network. These findings demonstrate modulation of serotonin during development may be sufficient to induce long-lasting changes in hippocampal neurogenesis.

scholarly journals Adult-born neurons maintain hippocampal cholinergic inputs and support working memory during aging

2018 ◽  
Author(s):  
Greer S. Kirshenbaum ◽  
Victoria K. Robson ◽  
Rebecca M. Shansky ◽  
Lisa M. Savage ◽  
E. David Leonardo ◽  
...  
Keyword(s):  
Working Memory ◽  
Adult Neurogenesis ◽  
Hippocampal Neurons ◽  
Normal Function ◽  
Hippocampal Neurogenesis ◽  
Stress Memory ◽  
Brain Connectome ◽  
Adult Born Neurons ◽  
Memory Deterioration

SummaryAdult neurogenesis is impaired in disorders of stress, memory, and cognition though its normal function remains unclear. Moreover, a systems level understanding of how a small number of young hippocampal neurons could dramatically influence brain function is lacking. We examined whether adult neurogenesis sustains hippocampal connections across the life span. Long-term suppression of neurogenesis as occurs during stress and aging resulted in a progressing decline in hippocampal acetylcholine and the slow emergence of profound working memory deficits. These deficits were accompanied by compensatory rewiring of cholinergic dentate gyrus inputs such that ventrally projecting neurons were recruited by the dorsal projection. Our study demonstrates that hippocampal neurogenesis supports memory by maintaining the septohippocampal circuit across the lifespan. It also provides a systems level explanation for the progressive nature of memory deterioration during normal and pathological aging and indicates that the brain connectome is malleable by experience.

scholarly journals Neuroinflammatory changes of the normal brain tissue in cured mice following combined radiation and anti-PD-1 blockade therapy for glioma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariano Guardia Clausi ◽  
Alexander M. Stessin ◽  
Zirun Zhao ◽  
Stella E. Tsirka ◽  
Samuel Ryu
Keyword(s):  
Brain Tissue ◽  
Cranial Irradiation ◽  
Subcortical White Matter ◽  
Glioma Cell Line ◽  
Hippocampal Neurogenesis ◽  
Normal Brain ◽  
Long Term Effects ◽  
Normal Brain Tissue ◽  
Molecule Inhibitor

AbstractThe efficacy of combining radiation therapy with immune checkpoint inhibitor blockade to treat brain tumors is currently the subject of multiple investigations and holds significant therapeutic promise. However, the long-term effects of this combination therapy on the normal brain tissue are unknown. Here, we examined mice that were intracranially implanted with murine glioma cell line and became long-term survivors after treatment with a combination of 10 Gy cranial irradiation (RT) and anti-PD-1 checkpoint blockade (aPD-1). Post-mortem analysis of the cerebral hemisphere contralateral to tumor implantation showed complete abolishment of hippocampal neurogenesis, but neural stem cells were well preserved in subventricular zone. In addition, we observed a drastic reduction in the number of mature oligodendrocytes in the subcortical white matter. Importantly, this observation was evident specifically in the combined (RT + aPD-1) treatment group but not in the single treatment arm of either RT alone or aPD-1 alone. Elimination of microglia with a small molecule inhibitor of colony stimulated factor-1 receptor (PLX5622) prevented the loss of mature oligodendrocytes. These results identify for the first time a unique pattern of normal tissue changes in the brain secondary to combination treatment with radiotherapy and immunotherapy. The results also suggest a role for microglia as key mediators of the adverse treatment effect.

scholarly journals Long-Term Overconsumption of Sugar Starting at Adolescence Produces Persistent Hyperactivity and Neurocognitive Deficits in Adulthood

2021 ◽  
Vol 15 ◽  
Author(s):  
Kate Beecher ◽  
Ignatius Alvarez Cooper ◽  
Joshua Wang ◽  
Shaun B. Walters ◽  
Fatemeh Chehrehasa ◽  
...  
Keyword(s):  
Dietary Habits ◽  
Hippocampal Neurogenesis ◽  
Neurocognitive Deficits ◽  
Long Term Effects ◽  
Sugar Consumption ◽  
Food And Beverages ◽  
Increased Risk ◽  
Newborn Neurons ◽  
Dependent Learning

Sugar has become embedded in modern food and beverages. This has led to overconsumption of sugar in children, adolescents, and adults, with more than 60 countries consuming more than four times (>100 g/person/day) the WHO recommendations (25 g/person/day). Recent evidence suggests that obesity and impulsivity from poor dietary habits leads to further overconsumption of processed food and beverages. The long-term effects on cognitive processes and hyperactivity from sugar overconsumption, beginning at adolescence are not known. Using a well-validated mouse model of sugar consumption, we found that long-term sugar consumption, at a level that significantly augments weight gain, elicits an abnormal hyperlocomotor response to novelty and alters both episodic and spatial memory. Our results are similar to those reported in attention deficit and hyperactivity disorders. The deficits in hippocampal-dependent learning and memory were accompanied by altered hippocampal neurogenesis, with an overall decrease in the proliferation and differentiation of newborn neurons within the dentate gyrus. This suggests that long-term overconsumption of sugar, as that which occurs in the Western Diet might contribute to an increased risk of developing persistent hyperactivity and neurocognitive deficits in adulthood.

scholarly journals Haploinsufficiency of the psychiatric risk gene Cyfip1 causes abnormal postnatal hippocampal neurogenesis through microglial and Arp2/3 mediated actin dependent mechanisms

2018 ◽  
Author(s):  
Niels Haan ◽  
Laura J Westacott ◽  
Jenny Carter ◽  
Michael J Owen ◽  
William P Gray ◽  
...  
Keyword(s):  
Genetic Risk ◽  
Hippocampal Neurons ◽  
Hippocampal Neurogenesis ◽  
Actin Dynamics ◽  
Biological Processes ◽  
Risk Gene ◽  
A Cell ◽  
Adult Born Neurons ◽  
Newborn Neurons ◽  
And Migration

AbstractGenetic risk factors can significantly increase chances of developing psychiatric disorders, but the underlying biological processes through which this risk is effected remain largely unknown. Here we show that haploinsufficiency of Cyfip1, a candidate risk gene present in the pathogenic 15q11.2(BP1-BP2) deletion may impact on psychopathology via abnormalities in cell survival and migration of newborn neurons during postnatal hippocampal neurogenesis. We demonstrate that haploinsufficiency of Cyfip1 leads to increased numbers of adult born hippocampal neurons due to reduced apoptosis, without altering proliferation. We confirm this is due to a cell autonomous failure of microglia to induce apoptosis through the secretion of the appropriate factors. Furthermore, we show an abnormal migration of adult-born neurons due to altered Arp2/3 mediated actin dynamics. Together, our findings throw new light on how the genetic risk candidate Cyfip1 may influence the hippocampus, a brain region with strong evidence for involvement in psychopathology.

scholarly journals The intellectual disability PAK3 R67C mutation impacts cognitive functions and adult hippocampal neurogenesis

2020 ◽  
Vol 29 (12) ◽  
pp. 1950-1968
Author(s):  
Charlotte Castillon ◽  
Laurine Gonzalez ◽  
Florence Domenichini ◽  
Sandrine Guyon ◽  
Kevin Da Silva ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Mouse Model ◽  
Spatial Memory ◽  
Adult Neurogenesis ◽  
Hippocampal Neurons ◽  
Memory Task ◽  
Clinical Signs ◽  
Hippocampal Neurogenesis ◽  
Adult Hippocampal Neurogenesis ◽  
Adult Born Neurons

Abstract The link between mutations associated with intellectual disability (ID) and the mechanisms underlying cognitive dysfunctions remains largely unknown. Here, we focused on PAK3, a serine/threonine kinase whose gene mutations cause X-linked ID. We generated a new mutant mouse model bearing the missense R67C mutation of the Pak3 gene (Pak3-R67C), known to cause moderate to severe ID in humans without other clinical signs and investigated hippocampal-dependent memory and adult hippocampal neurogenesis. Adult male Pak3-R67C mice exhibited selective impairments in long-term spatial memory and pattern separation function, suggestive of altered hippocampal neurogenesis. A delayed non-matching to place paradigm testing memory flexibility and proactive interference, reported here as being adult neurogenesis-dependent, revealed a hypersensitivity to high interference in Pak3-R67C mice. Analyzing adult hippocampal neurogenesis in Pak3-R67C mice reveals no alteration in the first steps of adult neurogenesis, but an accelerated death of a population of adult-born neurons during the critical period of 18–28 days after their birth. We then investigated the recruitment of hippocampal adult-born neurons after spatial memory recall. Post-recall activation of mature dentate granule cells in Pak3-R67C mice was unaffected, but a complete failure of activation of young DCX + newborn neurons was found, suggesting they were not recruited during the memory task. Decreased expression of the KCC2b chloride cotransporter and altered dendritic development indicate that young adult-born neurons are not fully functional in Pak3-R67C mice. We suggest that these defects in the dynamics and learning-associated recruitment of newborn hippocampal neurons may contribute to the selective cognitive deficits observed in this mouse model of ID.

scholarly journals Haploinsufficiency of the schizophrenia and autism risk gene Cyfip1 causes abnormal postnatal hippocampal neurogenesis through microglial and Arp2/3 mediated actin dependent mechanisms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Niels Haan ◽  
Laura J. Westacott ◽  
Jenny Carter ◽  
Michael J. Owen ◽  
William P. Gray ◽  
...  
Keyword(s):  
Genetic Risk ◽  
Hippocampal Neurons ◽  
Hippocampal Neurogenesis ◽  
Actin Dynamics ◽  
Biological Processes ◽  
Risk Gene ◽  
A Cell ◽  
Adult Born Neurons ◽  
Newborn Neurons ◽  
And Migration

AbstractGenetic risk factors can significantly increase chances of developing psychiatric disorders, but the underlying biological processes through which this risk is effected remain largely unknown. Here we show that haploinsufficiency of Cyfip1, a candidate risk gene present in the pathogenic 15q11.2(BP1–BP2) deletion may impact on psychopathology via abnormalities in cell survival and migration of newborn neurons during postnatal hippocampal neurogenesis. We demonstrate that haploinsufficiency of Cyfip1 leads to increased numbers of adult-born hippocampal neurons due to reduced apoptosis, without altering proliferation. We show this is due to a cell autonomous failure of microglia to induce apoptosis through the secretion of the appropriate factors, a previously undescribed mechanism. Furthermore, we show an abnormal migration of adult-born neurons due to altered Arp2/3 mediated actin dynamics. Together, our findings throw new light on how the genetic risk candidate Cyfip1 may influence the hippocampus, a brain region with strong evidence for involvement in psychopathology.

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