Multimodal transcriptomics reveal neurogenic aging trajectories and age-related regional inflammation in the dentate gyrus.

The mammalian dentate gyrus (DG) is involved in certain forms of learning and memory, and DG dysfunction has been implicated in age-related diseases. Although neurogenic potential is maintained throughout life in the DG as neural stem cells (NSCs) continue to generate new neurons, neurogenesis decreases with advancing age, with implications for age-related cognitive decline and disease. In this study, we used single-cell RNA sequencing to characterize transcriptomic signatures of neurogenic cells and their surrounding DG niche, identifying molecular changes associated with neurogenic aging from the activation of quiescent NSCs to the maturation of fate-committed progeny.

Chronic in vivo imaging defines age-dependent alterations of neurogenesis in the mouse hippocampus.

Neural stem cells (NSCs) generate new neurons throughout life in the mammalian hippocampus. Advancing age leads to a decline in neurogenesis, which is associated with impaired cognition. The cellular mechanisms causing reduced neurogenesis with advancing age remain largely unknown.

Characterization of the neurogenic niche in the aging dentate gyrus using iterative immunofluorescence imaging.

Advancing age causes reduced hippocampal neurogenesis, associated with age-related cognitive decline. The spatial relationship of age-induced alterations in neural stem cells (NSCs) and surrounding cells within the hippocampal niche remains poorly understood due to limitations of antibody-based cellular phenotyping. We established iterative indirect immunofluorescence imaging (4i) in tissue sections, allowing for simultaneous detection of 18 proteins to characterize NSCs and surrounding cells in 2-, 6-, and 12-month-old mice.

Long-term self-renewing stem cells in the adult mouse hippocampus identified by intravital imaging.

Neural stem cells (NSCs) generate neurons throughout life in the mammalian hippocampus. However, the potential for long-term self-renewal of individual NSCs within the adult brain remains unclear. We used two-photon microscopy and followed NSCs that were genetically labeled through conditional recombination driven by the regulatory elements of the stem cell-expressed genes GLI family zinc finger 1 (Gli1) or achaete-scute homolog 1 (Ascl1).

Adult-Born Hippocampal Neurons Undergo Extended Development and Are Morphologically Distinct from Neonatally-Born Neurons.

During immature stages, adult-born neurons pass through critical periods for survival and plasticity. It is generally assumed that by 2 months of age adult-born neurons are mature and equivalent to the broader neuronal population, raising questions of how they might contribute to hippocampal function in old age when neurogenesis has declined. However, few have examined adult-born neurons beyond the critical period or directly compared them to neurons born in infancy.

A combination of running and memantine increases neurogenesis and reduces activation of developmentally-born dentate granule neurons in rats.

During hippocampal-dependent memory formation, sensory signals from the neocortex converge in the dentate gyrus. It is generally believed that the dentate gyrus decorrelates inputs in order to minimize interference between codes for similar experiences, often referred to as pattern separation. The proportion of dentate neurons that are activated by experience is therefore likely to impact how memories are stored and separated.

Differential Effects of Extended Exercise and Memantine Treatment on Adult Neurogenesis in Male and Female Rats.

Adult neurogenesis has potential to ameliorate a number of disorders that negatively impact the hippocampus, including age-related cognitive decline, depression, and schizophrenia. A number of treatments enhance adult neurogenesis including exercise, NMDA receptor antagonism, antidepressant drugs and environmental enrichment. Despite the chronic nature of many disorders, most animal studies have only examined the efficacy of neurogenic treatments over short timescales (≤1 month).